Mux decrypt/verify redesign, HD DVD first-class, MVC 3D

decrypt:
- decrypt_sectors is now a pure decrypt (apply key, leave plaintext, report
  unverified bytes); TS-structure is a separate primitive (is_clean_ts/ps) used
  only for key selection and read-verify. The mux passes decrypted bytes through
  (the demuxer drops non-conforming packets), ending the NULL-TS conceal loop and
  the per-unit key-server refetch storm. Key-proof floor replaces the 75%
  supermajority.

recovery:
- Removed the post-read decrypt-verify gate (verify.rs) that mis-aligned the
  disc-absolute unit grid against clip-anchored AACS units and false-failed good
  clips (e.g. Dunkirk's orphan-CPS clip). Bad sectors are marked by physical read
  result; decryptability is proven at scan + mux time.

HD DVD (first-class AACS):
- Role-based candidate-list file sourcing so an HD DVD's /ANY!/ files
  (MKBROM.AACS, VTKF000.AACS, CONTENT_CERT.AACS) are found with no disc-type
  branch. parse_vtkf parses VTKF000.AACS into the same UnitKeyFile as a BD
  Unit_Key_RO.inf, so the shared VUK unwrap applies unchanged. set_unit_base
  clip-anchoring. Two decrypt-axis assumptions remain UNVERIFIED-HDDVD-DECRYPT
  (no encrypted disc to test).

mux:
- MVC (Blu-ray 3D) track signals unified into one MVCDecoderConfigurationRecord;
  release-safe track_vint (3-byte VINT) and pid_index (i32) guards.

hardening:
- Container-aware is_clean / encryption detection; bytes_bad_in_title fail-safe
  on a corrupt mapfile; CSS crack gated on DiscFormat::Dvd (HD DVD excluded);
  non-vacuous CSS tests; patch NOT_READY/HARDWARE/ILLEGAL_REQUEST/ABORTED
  sense-path tests.

src/aacs/derive.rs

@@ -463,7 +463,7 @@ pub enum KeyCandidate {
 /// PURE DERIVATION — no unit sampling, no validation. `unit_keys` holds every
 /// CPS-unit key the disc's `Unit_Key_RO.inf` yields from the VUK (paired with
 /// its declared CPS-unit number); the caller runs
-/// [`super::content::unit_key_validates`] to find which one actually opens the
+/// `decrypt_unit` + `is_clean_ts` to find which one actually opens the
 /// disc. Rungs above the candidate are `None`.
 #[derive(Debug, Clone)]
 pub struct ResolvedChain {
@@ -487,7 +487,7 @@ pub struct ResolvedChain {
 ///
 /// PURE DERIVATION: no sampling, no validation, no position recovery. Validate
 /// `unit_keys` against a real encrypted unit with
-/// [`super::content::unit_key_validates`] to prove the candidate opens the disc.
+/// `decrypt_unit` + `is_clean_ts` to prove the candidate opens the disc.
 ///
 /// Returns `None` only when derivation itself cannot proceed: a PK its MKB
 /// rejects, a `Dk` the MKB can't process, a missing VID on a path that needs
@@ -505,7 +505,8 @@ pub fn resolve_candidate(
         let version = mkb_type(mkb)
             .map(|t| t.generation())
             .unwrap_or(AacsVersion::V10);
-        let ukf = parse_unit_key_ro(unit_key_ro, version)?;
+        // BD/UHD Unit_Key_RO.inf or HD DVD VTKF000.AACS — dispatched by magic.
+        let ukf = parse_title_keys(unit_key_ro, version)?;
         if ukf.encrypted_keys.is_empty() {
             return None;
         }

src/aacs/inf.rs

@@ -161,6 +161,87 @@ pub fn parse_unit_key_ro(data: &[u8], version: AacsVersion) -> Option<UnitKeyFil
     })
 }
 
+/// HD DVD Video Title Key File (`VTKF000.AACS`) magic — "DVD HD Video TKF".
+pub const VTKF_MAGIC: &[u8; 12] = b"DVD_HD_V_TKF";
+/// Fixed header length before the first title-key entry.
+const VTKF_HEADER_LEN: usize = 0x80;
+/// Each title-key entry: BE32 flag + 16-byte encrypted key + 12-byte 0xFF pad.
+const VTKF_ENTRY_LEN: usize = 0x20;
+
+/// Parse an HD DVD `VTKF000.AACS` into the SAME [`UnitKeyFile`] a BD/UHD
+/// `Unit_Key_RO.inf` yields — so the shared AACS crypto (`derive_unit_keys` →
+/// `decrypt_unit_key(vuk, …)`) unwraps HD DVD title keys with no change. Only
+/// the on-disc CONTAINER differs between BD and HD DVD; the title-key unwrap is
+/// the identical AES-128 VUK step (`Kt = AES-128D(Kvu, Kte)`).
+///
+/// Layout (grounded in real discs — Shaun of the Dead, Anchorman, Harry Potter):
+/// ```text
+///   [0x00..0x0C] magic "DVD_HD_V_TKF"
+///   [0x0C..0x10] BE32 total file length
+///   [0x10..0x1C] associated playlist name ("VPLST000.XPL")
+///   [0x1C..0x80] reserved (zero)
+///   [0x80..]     32-byte entries: BE32 flag | 16-byte ENCRYPTED title key | 12-byte 0xFF pad
+///                flag bit 31 (0x8000_0000) set = present; a cleared flag ends the table
+///   [tail]       16-byte signature/MAC (never a key — the cleared-flag stop guards it)
+/// ```
+/// Entries number 1..=N as CPS units, matching `Unit_Key_RO`'s 1-based CPS
+/// numbering, so a title's CPS unit indexes this list identically. The
+/// title→CPS mapping itself is playlist-driven (`VPLST000.XPL`) and owned by the
+/// HD DVD enumerator, so `title_cps_unit` is left empty here.
+pub fn parse_vtkf(data: &[u8]) -> Option<UnitKeyFile> {
+    if data.len() < VTKF_HEADER_LEN || &data[..12] != VTKF_MAGIC {
+        return None;
+    }
+    // SHA1 of the WHOLE file — the KEYDB lookup key. BackupHDDVD-family key
+    // databases index an HD DVD disc by SHA1(VTKF000.AACS), the same role the
+    // BD disc_hash plays for `Unit_Key_RO.inf`.
+    let hash = disc_hash(data);
+
+    let mut encrypted_keys = Vec::new();
+    let mut pos = VTKF_HEADER_LEN;
+    let mut cps: u32 = 1;
+    while pos + VTKF_ENTRY_LEN <= data.len() {
+        let flag = u32::from_be_bytes([data[pos], data[pos + 1], data[pos + 2], data[pos + 3]]);
+        // A cleared present-bit terminates the key table. The file's trailing
+        // 16-byte signature then follows and must NOT be read as a key.
+        if flag & 0x8000_0000 == 0 {
+            break;
+        }
+        let mut key = [0u8; 16];
+        key.copy_from_slice(&data[pos + 4..pos + 20]);
+        encrypted_keys.push((cps, key));
+        cps += 1;
+        pos += VTKF_ENTRY_LEN;
+    }
+    if encrypted_keys.is_empty() {
+        return None;
+    }
+
+    Some(UnitKeyFile {
+        disc_hash: hash,
+        app_type: 0,     // HD DVD VTKF carries no BD-ROM app_type
+        num_bdmv_dir: 0, // BD-only concept
+        use_skb_mkb: false,
+        version: AacsVersion::V10, // HD DVD is always AACS 1.0
+        encrypted_keys,
+        title_cps_unit: Vec::new(),
+    })
+}
+
+/// Parse a disc's title-key file, dispatching on the self-describing magic:
+/// an HD DVD `VTKF000.AACS` (`DVD_HD_V_TKF`) → [`parse_vtkf`]; anything else is a
+/// BD/UHD `Unit_Key_RO.inf` → [`parse_unit_key_ro`]. Both return the same
+/// [`UnitKeyFile`], so every downstream AACS derivation stays container-agnostic
+/// — the single seam where BD-vs-HD-DVD key layout is resolved (mirrors the key
+/// service, which classifies HD DVD by the very same magic).
+pub fn parse_title_keys(data: &[u8], version: AacsVersion) -> Option<UnitKeyFile> {
+    if data.len() >= 12 && &data[..12] == VTKF_MAGIC {
+        parse_vtkf(data)
+    } else {
+        parse_unit_key_ro(data, version)
+    }
+}
+
 /// MKB disc structure format code.
 const MKB_DISC_STRUCTURE_FORMAT: u8 = 0x83;
 
@@ -283,3 +364,94 @@ pub fn parse_content_cert(data: &[u8]) -> Option<ContentCert> {
         version,
     })
 }
+
+#[cfg(test)]
+mod vtkf_tests {
+    use super::*;
+
+    /// Build a synthetic `VTKF000.AACS` matching the real on-disc layout
+    /// (Shaun of the Dead / Anchorman): magic, BE32 size, playlist name,
+    /// reserved to 0x80, then 32-byte present-flagged entries, a cleared-flag
+    /// terminator, and a 16-byte trailer.
+    fn synth_vtkf(keys: &[[u8; 16]]) -> Vec<u8> {
+        let mut v = Vec::new();
+        v.extend_from_slice(VTKF_MAGIC); // 0x00
+        v.extend_from_slice(&0u32.to_be_bytes()); // 0x0C size (patched below)
+        v.extend_from_slice(b"VPLST000.XPL"); // 0x10
+        v.resize(0x80, 0); // reserve to first entry
+        for k in keys {
+            v.extend_from_slice(&0x8000_0000u32.to_be_bytes()); // present flag
+            v.extend_from_slice(k); // 16-byte encrypted title key
+            v.extend_from_slice(&[0xFFu8; 12]); // 0xFF pad → 32-byte entry
+        }
+        // Cleared-flag terminator entry (must NOT be read as a key).
+        v.extend_from_slice(&[0u8; VTKF_ENTRY_LEN]);
+        // 16-byte trailing signature (must NOT be read as a key).
+        v.extend_from_slice(&[0xABu8; 16]);
+        let len = v.len() as u32;
+        v[0x0C..0x10].copy_from_slice(&len.to_be_bytes());
+        v
+    }
+
+    #[test]
+    fn parse_vtkf_extracts_present_entries_and_stops_at_terminator() {
+        let k1 = [0x11u8; 16];
+        let k2 = [0x22u8; 16];
+        let k3 = [0x33u8; 16];
+        let data = synth_vtkf(&[k1, k2, k3]);
+
+        let ukf = parse_vtkf(&data).expect("valid VTKF must parse");
+        // Exactly the three present entries — the cleared-flag terminator and
+        // the 16-byte trailer are NOT mistaken for keys.
+        assert_eq!(ukf.encrypted_keys.len(), 3, "must stop at the cleared flag");
+        assert_eq!(ukf.encrypted_keys[0], (1, k1), "CPS units number 1..=N");
+        assert_eq!(ukf.encrypted_keys[1], (2, k2));
+        assert_eq!(ukf.encrypted_keys[2], (3, k3));
+        assert_eq!(ukf.version, AacsVersion::V10, "HD DVD is AACS 1.0");
+        // disc_hash is SHA1 of the whole file (the KEYDB lookup key).
+        assert_eq!(ukf.disc_hash, disc_hash(&data));
+    }
+
+    #[test]
+    fn parse_vtkf_rejects_non_magic() {
+        let mut data = synth_vtkf(&[[0x11u8; 16]]);
+        data[0] = b'X'; // corrupt magic
+        assert!(
+            parse_vtkf(&data).is_none(),
+            "non-VTKF magic must be rejected"
+        );
+        assert!(
+            parse_vtkf(&[0u8; 4]).is_none(),
+            "too short must be rejected"
+        );
+    }
+
+    #[test]
+    fn parse_title_keys_dispatches_by_magic() {
+        // VTKF magic → parse_vtkf.
+        let data = synth_vtkf(&[[0x44u8; 16], [0x55u8; 16]]);
+        let ukf = parse_title_keys(&data, AacsVersion::V10).expect("VTKF dispatch");
+        assert_eq!(ukf.encrypted_keys.len(), 2);
+
+        // Non-VTKF → parse_unit_key_ro (a 2-byte buffer is not a valid inf, so
+        // this proves it ROUTED to the BD parser rather than parse_vtkf).
+        assert!(
+            parse_title_keys(&[0x00, 0x00], AacsVersion::V10).is_none(),
+            "non-magic input must route to parse_unit_key_ro"
+        );
+    }
+
+    /// The whole point of the seam: a parsed VTKF feeds the SHARED VUK→title-key
+    /// crypto (`decrypt_unit_key`) exactly like a BD `Unit_Key_RO.inf` would —
+    /// no HD-DVD-specific crypto path.
+    #[test]
+    fn vtkf_encrypted_keys_feed_shared_vuk_unwrap() {
+        let enc = [0x9Au8; 16];
+        let data = synth_vtkf(&[enc]);
+        let ukf = parse_vtkf(&data).unwrap();
+        let vuk = [0x5Cu8; 16];
+        let derived = super::super::derive::decrypt_unit_key(&vuk, &ukf.encrypted_keys[0].1);
+        // Same as applying the shared unwrap directly to the stored enc key.
+        assert_eq!(derived, super::super::derive::decrypt_unit_key(&vuk, &enc));
+    }
+}

src/aacs/mod.rs

@@ -40,10 +40,18 @@ pub mod types;
 pub mod variant;
 pub mod variant_select;
 
-/// On-disc UDF paths to the AACS key-input files (with their fallbacks).
-/// Centralised so every reader (`resolve_vid_only`, `read_aacs_inputs`,
-/// `read_mkb_content`, `read_aacs_version`) walks the exact same files — adding
-/// or changing a fallback in one place can then never silently diverge the
+/// On-disc UDF paths to the AACS key-input files.
+///
+/// BD and UHD keep their key material under `/AACS/…`; HD DVD keeps the
+/// equivalents under `/ANY!/…` with different names (`VTKF000.AACS` is the
+/// title-key file — magic `DVD_HD_V_TKF`; `MKBROM.AACS` is the MKB). The
+/// container difference is expressed here purely as DATA: each ROLE
+/// ([`UNIT_KEY_RO_PATHS`], [`MKB_PATHS`], [`CONTENT_CERT_PATHS`]) is an ordered
+/// candidate list, and every reader walks it with [`read_first`] taking the
+/// first that reads. No reader ever branches on disc type — a BD/UHD disc has
+/// the `/AACS/` files so those win; an HD DVD has neither, so it falls through
+/// to the `/ANY!/` entry. Centralised so `resolve_vid_only`, `read_aacs_inputs`,
+/// `read_mkb_content`, and `read_aacs_version` can never silently diverge the
 /// disc_hash / MKB / VID that another reader feeds a key service.
 pub const PATH_UNIT_KEY_RO: &str = "/AACS/Unit_Key_RO.inf";
 pub const PATH_UNIT_KEY_RO_DUPLICATE: &str = "/AACS/DUPLICATE/Unit_Key_RO.inf";
@@ -51,6 +59,46 @@ pub const PATH_MKB_RO: &str = "/AACS/MKB_RO.inf";
 pub const PATH_MKB_RW: &str = "/AACS/MKB_RW.inf";
 pub const PATH_CONTENT_CERT: &str = "/AACS/Content000.cer";
 pub const PATH_CONTENT_CERT_ALT: &str = "/AACS/Content001.cer";
+/// HD DVD title-key file (`/ANY!/`), forwarded as `inf_b64`; the key service
+/// recognises it by its `DVD_HD_V_TKF` magic.
+pub const PATH_VTKF_HDDVD: &str = "/ANY!/VTKF000.AACS";
+/// HD DVD Media Key Block (`/ANY!/`), forwarded as `mkb_b64`.
+pub const PATH_MKBROM_HDDVD: &str = "/ANY!/MKBROM.AACS";
+/// HD DVD content certificate (`/ANY!/`); byte 0 gives the AACS major (0x00 → V10).
+pub const PATH_CONTENT_CERT_HDDVD: &str = "/ANY!/CONTENT_CERT.AACS";
+
+/// Title-key / `Unit_Key_RO.inf` role, in resolution order (BD/UHD, then HD DVD).
+pub const UNIT_KEY_RO_PATHS: &[&str] = &[
+    PATH_UNIT_KEY_RO,
+    PATH_UNIT_KEY_RO_DUPLICATE,
+    PATH_VTKF_HDDVD,
+];
+/// MKB role, in resolution order (BD/UHD RO then RW, then HD DVD).
+pub const MKB_PATHS: &[&str] = &[PATH_MKB_RO, PATH_MKB_RW, PATH_MKBROM_HDDVD];
+/// Content-certificate role, in resolution order (BD/UHD, then HD DVD).
+pub const CONTENT_CERT_PATHS: &[&str] = &[
+    PATH_CONTENT_CERT,
+    PATH_CONTENT_CERT_ALT,
+    PATH_CONTENT_CERT_HDDVD,
+];
+
+/// Walk an AACS role's candidate paths and return the first that reads.
+///
+/// `read` performs the actual per-path read (full file or bounded prefix), so
+/// callers share the same first-present walk regardless of read style. Returns
+/// [`Error::AacsNoKeys`] if no candidate is present. This is the single place
+/// the `/AACS/` (BD/UHD) vs `/ANY!/` (HD DVD) layout difference is resolved.
+pub(crate) fn read_first<F>(candidates: &[&str], mut read: F) -> crate::error::Result<Vec<u8>>
+where
+    F: FnMut(&str) -> crate::error::Result<Vec<u8>>,
+{
+    for path in candidates {
+        if let Ok(buf) = read(path) {
+            return Ok(buf);
+        }
+    }
+    Err(crate::error::Error::AacsNoKeys)
+}
 
 // The module structure IS the public API — consumers import from the owning
 // module directly (e.g. `aacs::content::decrypt_unit`, `aacs::mkb::MkbType`,
@@ -61,7 +109,7 @@ pub const PATH_CONTENT_CERT_ALT: &str = "/AACS/Content001.cer";
 // content-decrypt entry points that downstream key-source crates import through
 // the `aacs::` path. These are the stable, load-bearing names; keeping them here
 // lets those crates track the module refactor without a lockstep re-pin.
-pub use content::{ALIGNED_UNIT_LEN, decrypt_unit_try_keys};
+pub use content::ALIGNED_UNIT_LEN;
 pub use derive::derive_vuk;
 pub use types::{DeviceKey, HostCert, MediaKey, ProcessingKey, UnitKey, Vid, Vuk};
 

src/aacs/resolve.rs

@@ -156,7 +156,7 @@ pub fn resolve_keys_v2(ctx: &ResolveContext<'_>) -> Option<ResolvedKeys> {
 /// equivalent of path 2 — there's no host-side PK derivation against a
 /// Variant MKB.)
 pub fn resolve_keys_v21(ctx: &ResolveContext<'_>) -> Option<ResolvedKeys> {
-    let uk_file = parse_unit_key_ro(ctx.unit_key_ro, AacsVersion::V20)?;
+    let uk_file = parse_title_keys(ctx.unit_key_ro, AacsVersion::V20)?;
     let hash_hex = disc_hash_hex(&uk_file.disc_hash);
     let bus_encryption = ctx
         .content_cert
@@ -280,8 +280,9 @@ fn resolve_keys_classical(ctx: &ResolveContext<'_>, version: AacsVersion) -> Opt
         .map(|cc| cc.bus_encryption)
         .unwrap_or(false);
 
-    // Parse Unit_Key_RO.inf at the version-appropriate stride.
-    let uk_file = parse_unit_key_ro(ctx.unit_key_ro, version)?;
+    // Parse the disc's title-key file (BD/UHD Unit_Key_RO.inf at the
+    // version-appropriate stride, or HD DVD VTKF000.AACS) → common UnitKeyFile.
+    let uk_file = parse_title_keys(ctx.unit_key_ro, version)?;
 
     let hash_hex = disc_hash_hex(&uk_file.disc_hash);
     let has_vid = *ctx.volume_id != [0u8; 16];

src/decrypt.rs

@@ -150,10 +150,15 @@ pub fn decrypt_threads() -> usize {
 pub enum DecryptKeys {
     /// No encryption on this disc.
     None,
-    /// AACS (Blu-ray / UHD). Unit keys + optional read data key.
+    /// AACS (Blu-ray / UHD / HD-DVD). Unit keys + optional read data key. The
+    /// `format` is the disc's content container (BD/UHD/FMTS = Transport Stream,
+    /// HD-DVD `.evo` = Program Stream); it travels with the keys because both are
+    /// resolved once per disc, and the key SELECTOR (`is_clean`) needs it to prove
+    /// a key structurally against the right container.
     Aacs {
         unit_keys: Vec<(u32, [u8; 16])>,
         read_data_key: Option<[u8; 16]>,
+        format: crate::disc::ContentFormat,
     },
     /// CSS (DVD). Title key for sector descrambling.
     Css { title_key: [u8; 5] },
@@ -206,7 +211,8 @@ pub fn decrypt_sectors(
 /// no TS sync, which would otherwise be mistaken for ciphertext). `base_lba` is
 /// the absolute LBA of `buf`'s first sector; aligned units are 3 sectors.
 ///
-/// `content_ranges` is sorted, merged, disjoint `[start_lba, end_lba)`.
+/// `content_ranges` is sorted, merged, disjoint `(start_lba, sector_count)`
+/// tuples (each covering `[start_lba, start_lba + sector_count)`).
 pub fn decrypt_sectors_in_content(
     buf: &mut [u8],
     keys: &mut DecryptKeys,
@@ -242,6 +248,7 @@ fn decrypt_sectors_impl(
         DecryptKeys::Aacs {
             unit_keys,
             read_data_key,
+            format,
         } => {
             // Validate that unit_key_idx is in-range before doing anything else.
             // This preserves the existing contract: an out-of-range explicit index
@@ -250,8 +257,13 @@ fn decrypt_sectors_impl(
                 return Err(crate::error::Error::DecryptFailed);
             }
 
-            // Strip CPS-unit IDs — the decrypt primitives only want the raw key bytes.
-            let raw_keys: Vec<[u8; 16]> = unit_keys.iter().map(|(_, k)| *k).collect();
+            // Container of this disc's content — the key SELECTOR (`is_clean`)
+            // checks the decrypted plaintext against the right structure (TS vs PS).
+            let format = *format;
+            // Index `unit_keys` directly for the raw key bytes (the `.1` of each
+            // `(cps_id, key)`); no per-call `Vec` of stripped keys — the decrypt
+            // closures only ever need `len()` / `[idx].1`, so collecting one would
+            // just be a heap alloc/free on every batch of the mux hot path.
             let rdk: Option<[u8; 16]> = *read_data_key;
             let unit_len = aacs::content::ALIGNED_UNIT_LEN;
             // AACS decrypts whole 6144-byte aligned units. The live mux path
@@ -295,7 +307,13 @@ fn decrypt_sectors_impl(
                     Some((base, ranges)) => lba_in_ranges(base.saturating_add(nfull * 3), ranges),
                     None => true,
                 };
-                if partial_in_content {
+                // TS-only: a scrambled trailing PARTIAL unit (< a full 6144-byte
+                // unit) can't be unit-decrypted, so fail loud. The heuristic is
+                // MPEG-TS sync density, which a PS (`.evo`) partial lacks entirely —
+                // running it on PS would false-trip `DecryptFailed`. HD-DVD partial-
+                // scramble detection is not yet wired (consistent with the UNVERIFIED
+                // PS path in `aacs_unit_encrypted`).
+                if partial_in_content && format == crate::disc::ContentFormat::BdTs {
                     let partial = &buf[buf.len() - partial_len..];
                     let packets = aacs::content::ts_packet_total(partial);
                     if packets > 0 && aacs::content::ts_sync_count(partial) <= packets / 2 {
@@ -336,12 +354,15 @@ fn decrypt_sectors_impl(
             // must happen first — it's a shared layer on top that is key-independent
             // across all CPS units on the disc.
             let decrypt_one = |chunk: &mut [u8]| {
-                // Gate on `aacs_unit_needs_decrypt` (CPI set AND TS syncs not yet
-                // restored): CPI alone isn't enough because the plaintext seed keeps
-                // the CPI bit set after decryption, so an already-decrypted unit would
-                // be decrypted a SECOND time (scrambling it) on any re-run of this
-                // pass. The intact-TS half makes it idempotent.
-                if chunk.len() != unit_len || !aacs::content::aacs_unit_needs_decrypt(chunk) {
+                // Gate on `aacs_unit_needs_decrypt` (encrypted-flag set AND structure
+                // not yet restored): the flag alone isn't enough because it lives in
+                // the plaintext header and survives decryption, so an already-decrypted
+                // unit would be decrypted a SECOND time (scrambling it) on any re-run of
+                // this pass. The structure-restored half makes it idempotent. This is
+                // ALSO the sole gate protecting the now-pure `decrypt_unit` from
+                // decrypting a clear unit.
+                if chunk.len() != unit_len || !aacs::content::aacs_unit_needs_decrypt(chunk, format)
+                {
                     return;
                 }
 
@@ -355,41 +376,67 @@ fn decrypt_sectors_impl(
                 // back to the full list skipping the hint.
                 let hint = last_key_idx.load(Ordering::Relaxed);
                 let try_order =
-                    std::iter::once(hint).chain((0..raw_keys.len()).filter(move |&i| i != hint));
+                    std::iter::once(hint).chain((0..unit_keys.len()).filter(move |&i| i != hint));
 
-                // DECRYPT the unit — apply a key, leave the plaintext. "Did a key
-                // produce clean TS?" is NOT "did we decrypt?": a correct key can
-                // decrypt content whose underlying encoding is broken (bad TS sync),
-                // which is a MUXER concern, never a decrypt verdict. Clean TS is used
-                // ONLY as a key-SELECTION hint on multi-CPS-unit discs — the first
-                // key that yields clean TS is the definite match. When none does we
-                // STILL decrypted (the cached-hint key is applied): keep those bytes
-                // and report the unit as UNVERIFIED. This function applies no policy;
-                // the caller decides what an unverified unit means (the mux passes it
-                // to the muxer; sweep/patch treat it as a read to recover or fail).
-                let mut applied: Option<Vec<u8>> = None;
+                // Compose the two SEGREGATED primitives explicitly. `decrypt_unit`
+                // is the decrypt (apply the key, leave the plaintext). `is_clean`
+                // is a SEPARATE structural question used here ONLY as a multi-CPS-unit
+                // key SELECTOR — the first key whose output is clean for the disc's
+                // container (`format`: TS or PS) is the match. "Did a key produce
+                // clean structure?" is NOT "did we decrypt?": a correct key can
+                // decrypt content whose encoding is broken (a muxer concern). When
+                // NO key yields clean structure we STILL decrypted (the cached-hint
+                // key is applied): keep those bytes and report the unit UNVERIFIED.
+                // This function applies no policy; the caller decides what unverified
+                // means (mux passes it to the muxer; sweep/patch recover or fail).
+
+                // Single-key fast path (the vast majority of titles): with no
+                // alternate key to fall back on there is nothing to try/rollback,
+                // so decrypt in place — no per-unit scratch alloc or copy-back.
+                // Clean → cache the hint; unclean → keep the applied bytes and
+                // tally unverified, exactly as the loop below would with one key.
+                if unit_keys.len() == 1 {
+                    aacs::content::decrypt_unit(chunk, &unit_keys[0].1);
+                    if aacs::content::is_clean(chunk, format) {
+                        last_key_idx.store(0, Ordering::Relaxed);
+                    } else {
+                        dropped_bytes.fetch_add(chunk.len(), Ordering::Relaxed);
+                    }
+                    return;
+                }
+
+                // Trial each key against a STACK scratch (unit_len is always
+                // ALIGNED_UNIT_LEN and the guard above proved chunk.len() == unit_len)
+                // so a failing attempt doesn't clobber the bus-decrypted base in
+                // `chunk` that the next key retries on — with no per-key heap Vec.
+                // `chunk` is NOT mutated in this loop, so on total miss we simply
+                // re-apply the first key in place (decrypt_unit is pure), which
+                // reproduces the first attempt without stashing its bytes.
+                let mut scratch = [0u8; aacs::content::ALIGNED_UNIT_LEN];
+                let scratch = &mut scratch[..chunk.len()];
+                let mut first_idx: Option<usize> = None;
                 for idx in try_order {
-                    if let Some(key) = raw_keys.get(idx) {
-                        // Work on a per-key copy so a failing attempt doesn't
-                        // clobber the bus-decrypted base we'll retry on.
-                        let mut attempt: Vec<u8> = chunk.to_vec();
-                        if aacs::content::decrypt_unit(&mut attempt, key) {
-                            chunk.copy_from_slice(&attempt);
+                    if let Some((_, key)) = unit_keys.get(idx) {
+                        scratch.copy_from_slice(chunk);
+                        aacs::content::decrypt_unit(scratch, key);
+                        if aacs::content::is_clean(scratch, format) {
+                            chunk.copy_from_slice(scratch);
                             last_key_idx.store(idx, Ordering::Relaxed);
                             return;
                         }
-                        if applied.is_none() {
-                            applied = Some(attempt);
+                        if first_idx.is_none() {
+                            first_idx = Some(idx);
                         }
                     }
                 }
 
-                // No key yielded clean TS. Keep the applied-key plaintext (the pool is
-                // non-empty past the guard, so `applied` is always `Some`) and tally
-                // the unit as unverified. Never restore ciphertext; that is a caller
-                // concern, threaded through the recovery ciphertext, not this seam.
-                if let Some(decrypted) = applied {
-                    chunk.copy_from_slice(&decrypted);
+                // No key yielded clean structure. Keep the first-tried key's
+                // plaintext (the pool is non-empty past the guard, so `first_idx` is
+                // always `Some`) and tally the unit as unverified. Never restore
+                // ciphertext; that is a caller concern, threaded through the recovery
+                // ciphertext, not this seam.
+                if let Some(idx) = first_idx {
+                    aacs::content::decrypt_unit(chunk, &unit_keys[idx].1);
                 }
                 dropped_bytes.fetch_add(chunk.len(), Ordering::Relaxed);
             };
@@ -427,11 +474,14 @@ fn decrypt_sectors_impl(
                 // back to the serial path rather than panic.
                 match decrypt_pool() {
                     Some(pool) => {
-                        let chunks: Vec<&mut [u8]> = buf.chunks_mut(unit_len).collect();
+                        // `par_chunks_mut` iterates the units in place — no
+                        // intermediate `Vec<&mut [u8]>` allocation per batch.
                         pool.install(|| {
-                            chunks.into_par_iter().enumerate().for_each(|(idx, chunk)| {
-                                process(idx, chunk);
-                            });
+                            buf.par_chunks_mut(unit_len)
+                                .enumerate()
+                                .for_each(|(idx, chunk)| {
+                                    process(idx, chunk);
+                                });
                         });
                     }
                     None => {
@@ -483,6 +533,7 @@ mod tests {
         let mut keys = DecryptKeys::Aacs {
             unit_keys: vec![(0, [0xAB; 16])],
             read_data_key: None,
+            format: crate::disc::ContentFormat::BdTs,
         };
         // The unit sits at LBA 0..3; the content extents are elsewhere (100..110),
         // so this nav unit is OUTSIDE content and the gate skips it untouched.
@@ -554,6 +605,7 @@ mod tests {
         let mut keys = DecryptKeys::Aacs {
             unit_keys: vec![(0, [0xAB; 16])],
             read_data_key: None,
+            format: crate::disc::ContentFormat::BdTs,
         };
         let original = scrambled_region(aacs::content::ALIGNED_UNIT_LEN);
 
@@ -587,6 +639,7 @@ mod tests {
         let mut keys = DecryptKeys::Aacs {
             unit_keys: vec![(0, [0xAB; 16])],
             read_data_key: None,
+            format: crate::disc::ContentFormat::BdTs,
         };
         let mut buf = scrambled_region(2 * aacs::content::ALIGNED_UNIT_LEN);
         // unit0 @ LBA 0 (clear/skip), unit1 @ LBA 3 (content). Content = [(3,3)].
@@ -605,6 +658,7 @@ mod tests {
         let mut keys_g = DecryptKeys::Aacs {
             unit_keys: vec![(0, [0xAB; 16])],
             read_data_key: None,
+            format: crate::disc::ContentFormat::BdTs,
         };
         let mut keys_u = keys_g.clone();
         let original = scrambled_region(aacs::content::ALIGNED_UNIT_LEN);
@@ -655,6 +709,7 @@ mod tests {
         let mut keys = DecryptKeys::Aacs {
             unit_keys: vec![(0, [0xAB; 16])],
             read_data_key: None,
+            format: crate::disc::ContentFormat::BdTs,
         };
         let original = scrambled_region(aacs::content::ALIGNED_UNIT_LEN);
         let mut buf = original.clone();
@@ -673,6 +728,7 @@ mod tests {
         let mut keys = DecryptKeys::Aacs {
             unit_keys: vec![(0, [0xAB; 16])],
             read_data_key: None,
+            format: crate::disc::ContentFormat::BdTs,
         };
         let original = clear_ts_region(aacs::content::ALIGNED_UNIT_LEN);
         let mut buf = original.clone();
@@ -791,6 +847,7 @@ mod tests {
         let mut keys = DecryptKeys::Aacs {
             unit_keys: vec![(0, [0xAB; 16])],
             read_data_key: None,
+            format: crate::disc::ContentFormat::BdTs,
         };
         let u = aacs::content::ALIGNED_UNIT_LEN;
         let mut buf = vec![0u8; 3 * u];
@@ -808,6 +865,7 @@ mod tests {
         let mut keys = DecryptKeys::Aacs {
             unit_keys: vec![(0, [0xAB; 16])],
             read_data_key: None,
+            format: crate::disc::ContentFormat::BdTs,
         };
         let mut buf = scrambled_region(2 * aacs::content::ALIGNED_UNIT_LEN);
         // unit0 @ LBA0 content, unit1 @ LBA3 out. Content = [(0,3)].
@@ -827,6 +885,7 @@ mod tests {
         let mut keys = DecryptKeys::Aacs {
             unit_keys: vec![(0, [0xAB; 16])],
             read_data_key: None,
+            format: crate::disc::ContentFormat::BdTs,
         };
         // One full clear unit + a scrambled single-sector partial, all OUTSIDE
         // content → the partial must be tolerated (Ok), not DecryptFailed.
@@ -849,6 +908,7 @@ mod tests {
         let mut keys = DecryptKeys::Aacs {
             unit_keys: vec![(0, [0xAB; 16])],
             read_data_key: None,
+            format: crate::disc::ContentFormat::BdTs,
         };
         // One full scrambled unit + a 2048-byte (single-sector) CLEAR tail.
         let unit = scrambled_region(aacs::content::ALIGNED_UNIT_LEN);
@@ -874,6 +934,7 @@ mod tests {
         let mut keys = DecryptKeys::Aacs {
             unit_keys: vec![(0, [0xAB; 16])],
             read_data_key: None,
+            format: crate::disc::ContentFormat::BdTs,
         };
         // One full unit + a 4096-byte (two-sector) SCRAMBLED tail.
         let unit = clear_ts_region(aacs::content::ALIGNED_UNIT_LEN);
@@ -896,6 +957,7 @@ mod tests {
         let mut keys = DecryptKeys::Aacs {
             unit_keys: vec![(0, [0xAB; 16])],
             read_data_key: None,
+            format: crate::disc::ContentFormat::BdTs,
         };
         let mut buf: Vec<u8> = Vec::new();
         assert!(decrypt_sectors(&mut buf, &mut keys, 0).is_ok());
@@ -909,6 +971,7 @@ mod tests {
         let mut keys = DecryptKeys::Aacs {
             unit_keys: vec![(0, [0xAB; 16])],
             read_data_key: None,
+            format: crate::disc::ContentFormat::BdTs,
         };
         let mut buf = clear_ts_region(aacs::content::ALIGNED_UNIT_LEN * 2);
         let snapshot = buf.clone();
@@ -950,6 +1013,7 @@ mod tests {
             DecryptKeys::Aacs {
                 unit_keys: vec![(0, [0; 16])],
                 read_data_key: None,
+                format: crate::disc::ContentFormat::BdTs,
             }
             .is_encrypted()
         );
@@ -1164,6 +1228,7 @@ mod tests {
         let mut keys = DecryptKeys::Aacs {
             unit_keys: vec![(0, [0xAB; 16])],
             read_data_key: None,
+            format: crate::disc::ContentFormat::BdTs,
         };
         let mut buf = clear_ts_region(aacs::content::ALIGNED_UNIT_LEN);
         let err = decrypt_sectors(&mut buf, &mut keys, 5)
@@ -1184,6 +1249,7 @@ mod tests {
         let mut keys = DecryptKeys::Aacs {
             unit_keys: vec![],
             read_data_key: None,
+            format: crate::disc::ContentFormat::BdTs,
         };
         let mut buf = clear_ts_region(aacs::content::ALIGNED_UNIT_LEN);
         let err = decrypt_sectors(&mut buf, &mut keys, 0).expect_err("empty unit_keys must error");
@@ -1265,6 +1331,7 @@ mod tests {
         let mut keys = DecryptKeys::Aacs {
             unit_keys: vec![(0, key0), (1, key1)], // two CPS units
             read_data_key: None,
+            format: crate::disc::ContentFormat::BdTs,
         };
 
         // Call with the default hint (idx 0) — the fix must fall back to key1.
@@ -1299,6 +1366,7 @@ mod tests {
         let mut keys = DecryptKeys::Aacs {
             unit_keys: vec![(0, key)],
             read_data_key: None,
+            format: crate::disc::ContentFormat::BdTs,
         };
         let mut buf = unit;
         decrypt_sectors(&mut buf, &mut keys, 0).expect("single-key disc must decrypt");
@@ -1340,6 +1408,7 @@ mod tests {
         let mut keys = DecryptKeys::Aacs {
             unit_keys: vec![(0, wrong_key)],
             read_data_key: None,
+            format: crate::disc::ContentFormat::BdTs,
         };
         let mut buf = unit;
         let unverified =
@@ -1383,6 +1452,7 @@ mod tests {
         let mut keys = DecryptKeys::Aacs {
             unit_keys: vec![(0, key)],
             read_data_key: None,
+            format: crate::disc::ContentFormat::BdTs,
         };
         let dropped = decrypt_sectors(&mut buf, &mut keys, 0).expect("partial decrypt is Ok");
 
@@ -1412,6 +1482,7 @@ mod tests {
         let mut keys = DecryptKeys::Aacs {
             unit_keys: vec![(0, key)],
             read_data_key: None,
+            format: crate::disc::ContentFormat::BdTs,
         };
         let mut buf = unit;
         let dropped = decrypt_sectors(&mut buf, &mut keys, 0).expect("clean decrypt");

src/disc/encrypt.rs

@@ -311,15 +311,11 @@ impl Disc {
     ) -> Result<AacsState> {
         use crate::aacs;
 
-        let uk_ro_data = udf_fs
-            .read_file(reader, crate::aacs::PATH_UNIT_KEY_RO)
-            .or_else(|_| udf_fs.read_file(reader, crate::aacs::PATH_UNIT_KEY_RO_DUPLICATE))
-            .map_err(|_| Error::AacsNoKeys)?;
+        let uk_ro_data =
+            aacs::read_first(aacs::UNIT_KEY_RO_PATHS, |p| udf_fs.read_file(reader, p))?;
         let dh = aacs::inf::disc_hash(&uk_ro_data);
 
-        let cc = udf_fs
-            .read_file(reader, crate::aacs::PATH_CONTENT_CERT)
-            .or_else(|_| udf_fs.read_file(reader, crate::aacs::PATH_CONTENT_CERT_ALT))
+        let cc = aacs::read_first(aacs::CONTENT_CERT_PATHS, |p| udf_fs.read_file(reader, p))
             .ok()
             .as_deref()
             .and_then(aacs::inf::parse_content_cert);

src/disc/extract.rs

@@ -288,63 +288,6 @@ impl Disc {
     }
 }
 
-/// True for the AACS-encrypted stream files (`.m2ts`, `.ssif`). Every other UDF
-/// file is clear (nav / playlists / filesystem) and needs no decrypt verify.
-fn is_aacs_clip(name: &str) -> bool {
-    let lower = name.to_ascii_lowercase();
-    lower.ends_with(".m2ts") || lower.ends_with(".ssif")
-}
-
-/// Enumerate the disc's AACS clip (`.m2ts`/`.ssif`) files as
-/// [`crate::disc::verify::ClipLayout`]s for the post-read verify gate: each
-/// clip's declared size plus its absolute disc extents in FILE order. Reads the
-/// UDF tree through `reader`.
-///
-/// FAIL-SAFE: any enumeration error (bad UDF read, name collision, …) yields an
-/// EMPTY list — the verify gate then covers nothing and the sweep behaves as
-/// today. Enumeration must never break a rip, so the error is logged, not
-/// propagated.
-pub(crate) fn clip_layouts(reader: &mut dyn SectorSource) -> Vec<crate::disc::verify::ClipLayout> {
-    let result = (|| -> Result<Vec<crate::disc::verify::ClipLayout>> {
-        let fs = udf::read_filesystem(reader)?;
-        let mut planned: Vec<PlannedFile> = Vec::new();
-        let mut dirs: Vec<PathBuf> = Vec::new();
-        let mut seen_hosts: std::collections::HashMap<PathBuf, String> =
-            std::collections::HashMap::new();
-        plan_tree(
-            reader,
-            &fs,
-            &fs.root,
-            Path::new(""),
-            "",
-            true,
-            &mut planned,
-            &mut dirs,
-            &mut seen_hosts,
-        )?;
-        Ok(planned
-            .into_iter()
-            .filter(|pf| pf.inline.is_none() && is_aacs_clip(&pf.disc_name))
-            .map(|pf| crate::disc::verify::ClipLayout {
-                size: pf.size,
-                extents: pf.extents,
-                // Every AACS clip we enumerate today is BD-TS (`.m2ts`/`.ssif`).
-                // HD-DVD `.evo` (program stream) maps to `ContainerKind::Ps` here
-                // once `is_aacs_clip` recognises it — the one-line HD-DVD hook.
-                container: crate::disc::verify::ContainerKind::Ts,
-            })
-            .collect())
-    })();
-    result.unwrap_or_else(|e| {
-        tracing::warn!(
-            target: "freemkv::verify",
-            error = %e,
-            "clip enumeration failed; post-read verify disabled for this pass"
-        );
-        Vec::new()
-    })
-}
-
 /// A borrowing `SectorSource` wrapper. Lets the decrypting decorator "own" an
 /// inner source for its lifetime while the caller keeps the underlying
 /// `&mut dyn SectorSource` (the decorator is a `DecryptingSectorSource<S>`

src/disc/mod.rs

@@ -10,7 +10,7 @@
 
 mod bluray;
 mod dvd;
-pub mod dvd_audio_probe;
+pub(crate) mod dvd_audio_probe;
 mod encrypt;
 mod extract;
 mod hddvd;
@@ -19,7 +19,6 @@ mod patch;
 pub mod read_error;
 mod section_recover;
 mod sweep;
-pub mod verify;
 
 use crate::drive::{Drive, extract_scsi_context};
 use crate::error::{Error, Result};
@@ -85,7 +84,8 @@ pub struct Disc {
 pub enum ContentFormat {
     /// Blu-ray BD Transport Stream (192-byte packets)
     BdTs,
-    /// DVD MPEG-2 Program Stream (VOB)
+    /// MPEG-2 Program Stream — DVD (`.vob`) and HD-DVD (`.evo`). For AACS content
+    /// this selects the PS-aware encrypted-flag / structural checks.
     MpegPs,
 }
 
@@ -1623,12 +1623,11 @@ impl Disc {
         // detection needs the read, the read needs auth, auth needs detection.
         // The handshake is itself the detector: on a non-CSS (unencrypted) DVD
         // the disc-key read fails, `resolve` returns None, and the disc is left
-        // in the clear. This block is DVD-only (MPEG-PS); BD/UHD (MPEG-TS) goes
-        // through the AACS handshake above and never reaches here.
-        if disc.css.is_none()
-            && disc.content_format == ContentFormat::MpegPs
-            && !disc.titles.is_empty()
-        {
+        // in the clear. This block is DVD-only: gate on `DiscFormat::Dvd`, NOT
+        // `content_format == MpegPs` — HD-DVD `.evo` is ALSO MPEG-PS but is AACS,
+        // not CSS, so it must never enter the CSS/REPORT-KEY handshake (it goes
+        // through the AACS path above). BD/UHD are MPEG-TS and never reach here.
+        if disc.css.is_none() && disc.format == DiscFormat::Dvd && !disc.titles.is_empty() {
             // CSS title keys are per-VTS, and ONLY the scrambled movie content
             // carries a non-zero key. Menu / VMG / logo cells (often the
             // low-LBA first extent) return a ZERO title key over REPORT KEY —
@@ -1744,10 +1743,13 @@ impl Disc {
         // pre-decrypted one. A pre-decrypted image has its scramble flags clear,
         // so `crack_key` finds no crackable sector and the disc stays in the
         // clear. AACS images go through KEYDB VUK lookup, not here.
-        if disc.css.is_none()
-            && disc.content_format == ContentFormat::MpegPs
-            && !disc.titles.is_empty()
-        {
+        //
+        // Gate on `DiscFormat::Dvd`, NOT `content_format == MpegPs`: HD-DVD
+        // `.evo` images are ALSO MPEG-PS but are AACS, not CSS — they must not
+        // enter the CSS crack path. A CSS DVD's IFO (which defines the titles
+        // this branch reads) is unscrambled, so `detect_format` reliably sets
+        // `Dvd` from the SD-resolution titles even on a still-scrambled image.
+        if disc.css.is_none() && disc.format == DiscFormat::Dvd && !disc.titles.is_empty() {
             let main_extents = match disc
                 .titles
                 .iter()
@@ -1799,10 +1801,9 @@ impl Disc {
         reader: &mut dyn SectorSource,
         udf_fs: &udf::UdfFs,
     ) -> Result<(Vec<u8>, Vec<u8>, u8)> {
-        let inf = udf_fs
-            .read_file(reader, crate::aacs::PATH_UNIT_KEY_RO)
-            .or_else(|_| udf_fs.read_file(reader, crate::aacs::PATH_UNIT_KEY_RO_DUPLICATE))
-            .map_err(|_| Error::AacsNoKeys)?;
+        let inf = crate::aacs::read_first(crate::aacs::UNIT_KEY_RO_PATHS, |p| {
+            udf_fs.read_file(reader, p)
+        })?;
         let mkb = Self::read_mkb_content(reader, udf_fs)?;
         let version = Self::read_aacs_version(reader, udf_fs);
         Ok((inf, mkb, version))
@@ -1820,12 +1821,12 @@ impl Disc {
     /// mis-strided title keys (silent wrong unit keys), so a missing cert must
     /// not quietly pick the V10 stride for a UHD disc.
     fn read_aacs_version(reader: &mut dyn SectorSource, udf_fs: &udf::UdfFs) -> u8 {
-        match udf_fs
-            .read_file(reader, crate::aacs::PATH_CONTENT_CERT)
-            .or_else(|_| udf_fs.read_file(reader, crate::aacs::PATH_CONTENT_CERT_ALT))
-            .ok()
-            .as_deref()
-            .and_then(crate::aacs::inf::parse_content_cert)
+        match crate::aacs::read_first(crate::aacs::CONTENT_CERT_PATHS, |p| {
+            udf_fs.read_file(reader, p)
+        })
+        .ok()
+        .as_deref()
+        .and_then(crate::aacs::inf::parse_content_cert)
         {
             Some(c) => c.version.major(),
             None => {
@@ -1856,10 +1857,9 @@ impl Disc {
         const MAX_BYTES: usize = 64 * 1024 * 1024;
         let mut want = START_BYTES;
         loop {
-            let buf = udf_fs
-                .read_file_prefix(reader, crate::aacs::PATH_MKB_RO, want)
-                .or_else(|_| udf_fs.read_file_prefix(reader, crate::aacs::PATH_MKB_RW, want))
-                .map_err(|_| Error::AacsNoKeys)?;
+            let buf = crate::aacs::read_first(crate::aacs::MKB_PATHS, |p| {
+                udf_fs.read_file_prefix(reader, p, want)
+            })?;
             let n = crate::aacs::mkb::mkb_content_len(&buf);
             // `n` strictly inside `buf` => the record walk reached the padding
             // boundary (full content captured). `buf` shorter than `want` =>
@@ -2297,12 +2297,15 @@ fn aligned_unit_keys_validate(
     unit_keys: &[(u32, [u8; 16])],
     read_data_key: Option<&[u8; 16]>,
     samples: &[Vec<u8>],
+    format: ContentFormat,
 ) -> bool {
-    use crate::aacs::content::{ALIGNED_UNIT_LEN, aacs_unit_needs_decrypt, decrypt_unit_full};
+    use crate::aacs::content::{
+        ALIGNED_UNIT_LEN, aacs_unit_needs_decrypt, decrypt_bus, decrypt_unit, is_clean,
+    };
     let scrambled: Vec<&[u8]> = samples
         .iter()
         .map(|s| s.as_slice())
-        .filter(|s| aacs_unit_needs_decrypt(s))
+        .filter(|s| aacs_unit_needs_decrypt(s, format))
         .collect();
     if scrambled.is_empty() {
         return true; // nothing to disprove against — accept
@@ -2324,7 +2327,13 @@ fn aligned_unit_keys_validate(
             hb.tick_cpu(tried, total);
             tried += 1;
             probe.copy_from_slice(&sample[..ALIGNED_UNIT_LEN]);
-            if decrypt_unit_full(&mut probe, k, read_data_key) {
+            // bus layer (AACS 2.0) first, then the CPS unit key, then the structural
+            // proof — the composed form of the old `decrypt_unit_full`.
+            if let Some(rdk) = read_data_key {
+                decrypt_bus(&mut probe, rdk);
+            }
+            decrypt_unit(&mut probe, k);
+            if is_clean(&probe, format) {
                 covered = true;
                 break;
             }
@@ -2351,6 +2360,7 @@ impl Disc {
             crate::decrypt::DecryptKeys::Aacs {
                 unit_keys: aacs.unit_keys.clone(),
                 read_data_key: aacs.read_data_key,
+                format: self.content_format,
             }
         } else if let Some(ref css) = self.css {
             crate::decrypt::DecryptKeys::Css {
@@ -2840,7 +2850,12 @@ impl Disc {
         // de-scramble it. With no samples (or only clear ones) there is nothing
         // to disprove against, so the key is accepted as-is — keeping the
         // sample-less paths (resume / mapfile cache) byte-for-byte unchanged.
-        if !aligned_unit_keys_validate(&candidate_unit_keys, read_data_key.as_ref(), samples) {
+        if !aligned_unit_keys_validate(
+            &candidate_unit_keys,
+            read_data_key.as_ref(),
+            samples,
+            self.content_format,
+        ) {
             return Err(crate::error::Error::AacsKeyRejected);
         }
 
@@ -3073,10 +3088,6 @@ impl Disc {
             progress: opts.progress,
             halt: opts.halt.clone(),
             key_fetch: opts.key_fetch.clone(),
-            // Disc::copy's internal patch grinds each range fully (it's a
-            // single-call recovery); the breadth-first fast-capture ordering is
-            // an autorip multi-pass concern.
-            fast_capture: false,
         };
         let pr = self.patch(reader, path, &patch_opts)?;
         tracing::info!(
@@ -3131,27 +3142,15 @@ impl Disc {
         // A decrypting sweep (`opts.decrypt`, e.g. `disc:// → iso://` without
         // `--raw`) decrypts each unit IN PLACE → the ISO holds plaintext.
         //
-        // A NON-decrypting MULTIPASS sweep (`!opts.decrypt && skip_on_error`, the
-        // autorip / `--multipass` path) writes the ISO as CIPHERTEXT, but we
-        // still resolve the keys and VERIFY each unit on a scratch copy: a unit
-        // that won't decrypt fails the read (`DECRYPT_VERIFY_READ`) exactly like
-        // a SCSI error, and flows into the SAME read-error recovery (skip /
-        // NonTrimmed / patch). This is the one spot that makes "a read succeeded"
-        // mean "read AND decrypts" — everything downstream is unchanged. With no
-        // usable AACS keys (no keydb) it degrades to a plain pass-through.
-        //
-        // A plain `--raw` single-pass (no `skip_on_error`) stays a pass-through:
-        // the user asked for the raw image, untouched and unchecked.
-        // The sweep COPIES ciphertext (multipass / `--raw`) or decrypts IN PLACE
-        // (`opts.decrypt`, the rare disc→decrypted-ISO). It deliberately does NOT
-        // decrypt-VERIFY: a whole-disc sweep reads disc-absolute, but AACS aligned
-        // units are anchored to each clip's FILE start and clips can be non-6144-
-        // aligned OR fragmented across UDF extents — so a disc-absolute verify
-        // mis-aligns the unit grid and false-fails good clips (it skipped the
-        // ~990 MB orphan-CPS clip on Dunkirk). Verification moved to the
-        // clip-anchored [`Disc::verify_clips`] pass that runs AFTER the sweep,
-        // reading each clip file-order-anchored from the ISO. The read here stays
-        // a fail-safe copy; alignment is never assumed.
+        // Every other sweep (`!opts.decrypt`: the autorip / `--multipass` path and
+        // plain `--raw`) writes the ISO as CIPHERTEXT verbatim — keys = `None`, a
+        // pure pass-through. Bad sectors are found by PHYSICAL read success (a SCSI
+        // read error → skip / NonTrimmed → patch re-read), NOT by decrypt structure.
+        // (The old decrypt-VERIFY read gate — which mis-aligned the disc-absolute
+        // unit grid against clip-file-anchored AACS units and false-failed good
+        // clips like Dunkirk's orphan-CPS clip — was removed. There is no scratch
+        // verify and no post-sweep clip-anchored pass; decryptability is proven at
+        // mux time, not at capture time.)
         let keys = if opts.decrypt {
             self.decrypt_keys()
         } else {
@@ -3177,22 +3176,6 @@ impl Disc {
         };
         let reader = &mut reader;
 
-        // Post-read verify gate (universal `read -> verify -> sign-off`). Built
-        // ONLY for the ciphertext sweep (`!opts.decrypt`, the multipass rip
-        // path) so `observe` always sees on-disc ciphertext and never
-        // double-decrypts already-plaintext bytes. `UnitVerifier::new` is itself
-        // fail-safe: it returns `None` (verify disabled, behavior unchanged) for
-        // a non-AACS disc, no keys, the kill-switch off, or an empty clip
-        // enumeration. We resolve the REAL AACS keys here even though the sweep
-        // copies ciphertext, and reuse the application's key-fetch seam.
-        let mut verifier = if opts.decrypt {
-            None
-        } else {
-            let verify_keys = self.decrypt_keys();
-            let layouts = extract::clip_layouts(&mut *reader);
-            crate::disc::verify::UnitVerifier::new(&layouts, &verify_keys, opts.key_fetch.clone())
-        };
-
         // Mapfile: load if resuming, else wipe + recreate.
         let mapfile_path = self.mapfile_for(path);
         // covers_disc reconciliation. A resume against a mapfile whose total
@@ -3483,18 +3466,6 @@ impl Disc {
                         // The consumer thread sees decrypted bytes; the
                         // pre-0.18 inline decrypt_sectors call lived here.
 
-                        // Post-read verify: observe the just-read ciphertext
-                        // BEFORE it is moved into the channel, collecting the
-                        // clip units this batch completes that are confidently
-                        // undecryptable. Sent as `MarkBad` AFTER the `Good`
-                        // below so the FIFO pipe records `Finished` first and the
-                        // downgrade to `NonTrimmed` last. No-op when the gate is
-                        // disabled (`verifier` is `None`).
-                        let verify_bad = verifier
-                            .as_mut()
-                            .map(|v| v.observe(block_lba, &buf[..block_bytes as usize]))
-                            .unwrap_or_default();
-
                         // Move the batch into the channel via fresh
                         // owned Vec. The producer's `buf` is reused
                         // for the next read.
@@ -3503,26 +3474,6 @@ impl Disc {
                             producer_err = Some(consumer_gone());
                             break 'outer;
                         }
-                        // Downgrade any unit that failed verify (decrypt-fail ==
-                        // bad read). decrypt-fail is NOT physical damage, so it
-                        // deliberately does not touch the damage-jump window.
-                        let mut send_failed = false;
-                        for (bad_lba, bad_cnt) in verify_bad {
-                            if pipe
-                                .send(WorkItem::MarkBad {
-                                    pos: bad_lba as u64 * 2048,
-                                    len: bad_cnt as u64 * 2048,
-                                })
-                                .is_err()
-                            {
-                                producer_err = Some(consumer_gone());
-                                send_failed = true;
-                                break;
-                            }
-                        }
-                        if send_failed {
-                            break 'outer;
-                        }
                         bytes_done = bytes_done.saturating_add(block_bytes);
                         pos += block_bytes;
                     }
@@ -4009,18 +3960,6 @@ pub struct PatchOptions<'a> {
     /// On-decrypt-miss key fetch (see [`CopyOptions::key_fetch`]). Lets Pass N
     /// recover an orphan CPS unit's key when re-reading its bad range.
     pub key_fetch: Option<crate::sector::KeyFetch>,
-    /// Fast-capture pass: read each bad range ONCE at the full batch and leave
-    /// every failed block `NonTrimmed` for a later pass — WITHOUT bisecting,
-    /// re-reading, or grinding it here. This lets a first retry pass grab the
-    /// readable blocks (the sweep's good skip-ahead overshoot) of EVERY range
-    /// quickly, before any single range's slow per-sector recovery — so
-    /// recovered data surfaces across the whole disc first instead of grinding
-    /// section 1 to exhaustion before even touching section 2. A later pass
-    /// (`fast_capture = false`) does the granular bisect/retry on what's left.
-    /// No data is dropped: a failed block stays `NonTrimmed` until a granular
-    /// pass recovers it or finally gives up. A transport fault (bridge crash)
-    /// still aborts — it isn't a recoverable bad sector.
-    pub fast_capture: bool,
 }
 
 /// Result returned by [`Disc::patch`].
@@ -4867,6 +4806,7 @@ mod tests {
             crate::decrypt::DecryptKeys::Aacs {
                 unit_keys,
                 read_data_key,
+                ..
             } => {
                 assert_eq!(unit_keys, uk, "injected UK must be the decrypt key");
                 assert_eq!(read_data_key, None, "ISO mux needs no bus key");
@@ -5393,7 +5333,8 @@ mod tests {
         assert!(super::aligned_unit_keys_validate(
             &[(0, [0x11u8; 16])],
             None,
-            &[]
+            &[],
+            ContentFormat::BdTs
         ));
 
         // A clear unit (TS syncs intact) is not scrambled -> proves nothing ->
@@ -5408,7 +5349,8 @@ mod tests {
         assert!(super::aligned_unit_keys_validate(
             &[(0, [0x11u8; 16])],
             None,
-            &[clear.clone()]
+            &[clear.clone()],
+            ContentFormat::BdTs
         ));
 
         // A genuinely scrambled unit the RIGHT key restores to clear TS.
@@ -5423,16 +5365,23 @@ mod tests {
         assert!(super::aligned_unit_keys_validate(
             &[(7, uk)],
             None,
-            &[enc.clone()]
+            &[enc.clone()],
+            ContentFormat::BdTs
         ));
         // Wrong key -> cannot de-scramble a scrambled sample -> reject.
         assert!(!super::aligned_unit_keys_validate(
             &[(7, [0x00u8; 16])],
             None,
-            &[enc.clone()]
+            &[enc.clone()],
+            ContentFormat::BdTs
         ));
         // Empty key set against a scrambled sample -> reject.
-        assert!(!super::aligned_unit_keys_validate(&[], None, &[enc]));
+        assert!(!super::aligned_unit_keys_validate(
+            &[],
+            None,
+            &[enc],
+            ContentFormat::BdTs
+        ));
     }
 
     #[test]
@@ -5467,21 +5416,24 @@ mod tests {
         assert!(!super::aligned_unit_keys_validate(
             &[(0, uk0)],
             None,
-            &samples
+            &samples,
+            ContentFormat::BdTs
         ));
 
         // Complete key set (both CPS units) -> accept.
         assert!(super::aligned_unit_keys_validate(
             &[(0, uk0), (1, uk1)],
             None,
-            &samples
+            &samples,
+            ContentFormat::BdTs
         ));
 
         // Order-independent: covering key present anywhere in the set is fine.
         assert!(super::aligned_unit_keys_validate(
             &[(1, uk1), (0, uk0)],
             None,
-            &samples
+            &samples,
+            ContentFormat::BdTs
         ));
     }
 

src/disc/patch.rs

@@ -405,9 +405,15 @@ pub(super) fn compute_initial_state(
         bad_ranges.reverse();
     }
     let work_total: u64 = bad_ranges.iter().map(|(_, sz)| *sz).sum();
+    // Fail SAFE when metadata is indeterminate: assume a regular file so a
+    // real `sync_all` failure is surfaced, not swallowed. `/dev/null` and pipes
+    // report success-with-non-file here (so they still correctly map to
+    // `false`); only a genuine metadata error (e.g. transient NFS ESTALE) hits
+    // the default, and for a data-integrity guard "surface the error" is the
+    // right side to err on.
     let is_regular = std::fs::metadata(path)
         .map(|m| m.file_type().is_file())
-        .unwrap_or(false);
+        .unwrap_or(true);
     Ok((
         map,
         initial_stats,
@@ -1247,7 +1253,24 @@ impl Disc {
     pub fn bytes_bad_in_title(&self, mapfile_path: &std::path::Path, title: &DiscTitle) -> u64 {
         let map = match mapfile::Mapfile::load(mapfile_path) {
             Ok(m) => m,
-            Err(_) => return 0,
+            // A MISSING mapfile is legitimate (no damage was ever tracked — e.g. a
+            // clean single-pass rip): 0 bad bytes is correct. Any OTHER load error
+            // (corrupt / unreadable mapfile) means we CANNOT know the damage — and
+            // a returned 0 reads to the caller as "clean." Logging alone is not
+            // fail-safe: the RETURN VALUE drives the loss/abort accounting, not the
+            // log. So fail safe by reporting the ENTIRE title as bad (its full
+            // in-extent byte count) — a corrupt damage record must surface as
+            // maximal loss, never as a clean rip.
+            Err(e) if e.kind() == std::io::ErrorKind::NotFound => return 0,
+            Err(e) => {
+                tracing::warn!(
+                    target: "freemkv::disc",
+                    path = %mapfile_path.display(),
+                    error = %e,
+                    "bytes_bad_in_title: mapfile load failed; reporting whole title bad (fail-safe: cannot confirm clean)"
+                );
+                return bytes_bad_in_title(title, &[(0, u64::MAX)]);
+            }
         };
         let bad_ranges = map.ranges_with(&[
             mapfile::SectorStatus::NonTrimmed,
@@ -1299,33 +1322,13 @@ impl Disc {
         let bytes_good_before = initial_stats.bytes_good;
         let bytes_good_start = bytes_good_before;
 
-        // Post-read verify gate for the patch pass (ciphertext multipass only,
-        // `!opts.decrypt`). Built here from the raw reader's UDF enumeration;
-        // reused AFTER the recovery loop (`reverify_iso`) to re-check the units
-        // this pass touched by reading them WHOLE back from the patched ISO —
-        // patch re-reads only the bad sectors of a unit, so per-unit verify
-        // can't run live. Fail-safe `None` when disabled / non-AACS / no keys.
-        let mut verifier = if opts.decrypt {
-            None
-        } else {
-            let verify_keys = self.decrypt_keys();
-            let layouts = crate::disc::extract::clip_layouts(&mut *reader);
-            crate::disc::verify::UnitVerifier::new(&layouts, &verify_keys, opts.key_fetch.clone())
-        };
         // Decrypt-aware read — symmetric with `Disc::sweep`. A decrypting patch
-        // (`opts.decrypt`) decrypts in place (plaintext ISO). A NON-decrypting
-        // patch (the multipass / `--raw --multipass` path) resolves the keys and
-        // VERIFIES each unit on a scratch copy: a re-read that STILL won't decrypt
-        // fails the read (`DECRYPT_VERIFY_READ`) and stays NonTrimmed, so the
-        // retry loop keeps re-reading it "until it decrypts or retries exhaust"
-        // exactly as for a SCSI read error — and a unit that DOES decrypt on a
-        // fresh read (the drive returned different bytes) is recovered for free.
-        // With no usable AACS keys this degrades to a plain pass-through.
-        // Symmetric with `Disc::sweep`: the patch COPIES ciphertext (multipass /
-        // `--raw`) or decrypts IN PLACE (`opts.decrypt`). It does NOT decrypt-
-        // VERIFY — the disc-absolute read can't anchor to a clip's file-relative
-        // unit grid (see `Disc::sweep` + `Disc::verify_clips`). Re-reads recover
-        // bad sectors; the clip-anchored verify pass re-checks them afterward.
+        // (`opts.decrypt`) decrypts in place (plaintext ISO); a NON-decrypting
+        // patch (the multipass / `--raw --multipass` path) copies ciphertext
+        // verbatim (keys = `None` → pass-through). Bad sectors are found by
+        // PHYSICAL read success, not by decrypt structure: a re-read that returns
+        // good bytes recovers the range; a read that errors leaves it NonTrimmed
+        // for the next pass. (The old decrypt-VERIFY read gate was removed.)
         let keys = if opts.decrypt {
             self.decrypt_keys()
         } else {
@@ -1435,64 +1438,7 @@ impl Disc {
         // sink's summary. `close` failing on a regular-file sync_all is
         // surfaced here as `Error::IoError`, matching pre-split
         // behaviour.
-        let mut summary = pipe.finish()?;
-
-        // Scoped post-read re-verify (decrypt-fail == bad read). The consumer
-        // has flushed the ISO + mapfile; re-read each clip unit this pass touched
-        // WHOLE from the patched ISO and downgrade any that still won't decrypt
-        // to NonTrimmed, so the orchestrator's end-of-recovery promotion
-        // terminalizes it. Reuses the same verifier as the sweep. Fail-safe:
-        // disabled gate / unreadable ISO / load failure all leave the pass as-is.
-        if let Some(mut v) = verifier.take() {
-            if let Ok(mut m) = mapfile::Mapfile::load(&mapfile_path) {
-                // Only units whose every backing sector was actually READ
-                // (Finished) may be re-verified — we can't verify what wasn't read
-                // (a non-Finished sector is zero-filled because the read failed),
-                // and must not waste a key lookup on a known-bad block.
-                let finished = m.ranges_with(&[mapfile::SectorStatus::Finished]);
-                let is_finished = |lba: u32| -> bool {
-                    let p = lba as u64 * 2048;
-                    finished.iter().any(|&(s, sz)| p >= s && p < s + sz)
-                };
-                if let Ok(mut iso) = crate::io::file_sector_source::FileSectorSource::open(path) {
-                    let bad = v.reverify_iso(&mut iso, &bad_ranges, &is_finished);
-                    if !bad.is_empty() {
-                        let n: usize = bad.len();
-                        for (lba, cnt) in bad {
-                            if let Err(e) = m.record(
-                                lba as u64 * 2048,
-                                cnt as u64 * 2048,
-                                mapfile::SectorStatus::NonTrimmed,
-                            ) {
-                                tracing::warn!(
-                                    lba,
-                                    "reverify downgrade: mapfile record failed ({e}) — unit may stay mismarked as good"
-                                );
-                            }
-                        }
-                        if let Err(e) = m.flush() {
-                            tracing::warn!(
-                                "reverify downgrade: mapfile flush failed ({e}) — downgrade not persisted; a resume could mismark it good"
-                            );
-                        }
-                        // The re-verify ran AFTER `pipe.finish()` snapshotted
-                        // `summary.stats`, so those stats still count the just-
-                        // downgraded units as good. Refresh from the mapfile so
-                        // `build_outcome` reports the true post-downgrade picture
-                        // (bytes_good ↓, bytes_pending ↑) — otherwise the caller
-                        // over-reports recovery and can call an imperfect rip
-                        // "complete".
-                        summary.stats = m.stats();
-                        tracing::info!(
-                            target: "freemkv::verify",
-                            phase = "patch.reverify",
-                            downgraded_ranges = n,
-                            "post-read re-verify downgraded undecryptable units to NonTrimmed"
-                        );
-                    }
-                }
-            }
-        }
+        let summary = pipe.finish()?;
 
         let outcome = build_outcome(
             &state,

src/disc/sweep.rs

@@ -66,14 +66,6 @@ pub(super) enum WorkItem {
     /// tell them apart without parsing a flag.
     GapFill { pos: u64, len: u64 },
 
-    /// Post-read verify downgrade. The producer's `UnitVerifier` found that the
-    /// just-`Finished` clip unit at `[pos, pos+len)` is confidently undecryptable
-    /// (a silent bad read). The consumer re-records the range as `NonTrimmed` so
-    /// the patch pass re-reads it — the ISO bytes (ciphertext) already written by
-    /// the preceding `Good` are left in place for the patch to overwrite. FIFO
-    /// pipe ordering guarantees this arrives AFTER the `Good` that wrote them.
-    MarkBad { pos: u64, len: u64 },
-
     /// Producer wants the latest mapfile stats for the progress
     /// callback. Consumer responds on `prog_tx` with a fresh
     /// [`ProgressSnapshot`]. Best-effort: if the producer hasn't
@@ -182,12 +174,6 @@ impl Sink<WorkItem> for SweepSink {
                 }
                 self.map.record(pos, len, SectorStatus::NonTrimmed)?;
             }
-            WorkItem::MarkBad { pos, len } => {
-                // Verify downgrade: the ISO bytes are already written by the
-                // preceding Good; only the mapfile status changes so patch
-                // re-reads this range. No file write.
-                self.map.record(pos, len, SectorStatus::NonTrimmed)?;
-            }
             WorkItem::StatsRequest => {
                 let stats = self.map.stats();
                 // DAMAGE only — NOT NonTried. NonTried is the unread remainder

src/io/file_sector_source/mod.rs

@@ -78,8 +78,8 @@ use crate::consts::{SECTOR_BYTES, SECTOR_BYTES_U64};
 /// read side. Mirrors `WRITEBACK_CHUNK_BYTES` so the read-side page
 /// cache stays bounded the same way the write side does.
 ///
-/// 32 MiB is the empirically tuned value on the rip1 test bed (single
-/// 7200rpm HDD via SATA): smaller windows (8 / 16 MiB) shorten the
+/// 32 MiB is the empirically tuned value on a 7200rpm HDD via SATA:
+/// smaller windows (8 / 16 MiB) shorten the
 /// kernel-readahead overlap and slow the producer; larger windows
 /// (64 / 128 MiB) let the page cache pin enough of the ISO to
 /// pressure concurrent writes. Override via `FREEMKV_READ_DROP_CHUNK_MIB`.

src/keysource.rs

@@ -407,7 +407,7 @@ pub fn read_encrypted_units(
                     break;
                 }
                 let u = &buf[o..o + ALIGNED_UNIT_LEN];
-                if aacs_unit_encrypted(u) {
+                if aacs_unit_encrypted(u, title.content_format) {
                     out.push(u.to_vec());
                     if out.len() >= n {
                         return out;
@@ -717,7 +717,7 @@ mod tests {
         );
         for s in &samples {
             assert!(
-                aacs_unit_encrypted(s),
+                aacs_unit_encrypted(s, crate::disc::ContentFormat::BdTs),
                 "every sample is a CPI-flagged encrypted unit (byte0 & 0xC0 != 0)"
             );
         }
@@ -800,7 +800,7 @@ mod tests {
         );
         for s in &samples {
             assert!(
-                aacs_unit_encrypted(s),
+                aacs_unit_encrypted(s, crate::disc::ContentFormat::BdTs),
                 "only CPI-flagged units are selected"
             );
             assert_eq!(

src/mux/demux_sink.rs

@@ -241,11 +241,23 @@ impl EsWriter for AnnexBWriter {
 /// Delegates to the canonical hvcC/avcC → Annex-B converters in
 /// [`crate::mux::hevc`] — the single source of truth across all muxers.
 fn annexb_param_sets(codec: Codec, record: &[u8]) -> Vec<u8> {
-    match codec {
-        Codec::Hevc => hvcc_to_annex_b(record).unwrap_or_default(),
-        Codec::H264 => avcc_to_annex_b(record).unwrap_or_default(),
-        _ => Vec::new(),
-    }
+    let converted = match codec {
+        Codec::Hevc => hvcc_to_annex_b(record),
+        Codec::H264 => avcc_to_annex_b(record),
+        _ => return Vec::new(),
+    };
+    converted.unwrap_or_else(|| {
+        // A malformed hvcC/avcC record yields no parameter sets. Returning empty
+        // means keyframes ship WITHOUT in-band SPS/PPS — playable from the first
+        // keyframe but broken for seek-to-arbitrary-point and hardware decoders.
+        // Surface it rather than silently degrading the output.
+        tracing::warn!(
+            target: "mux",
+            ?codec,
+            "codec-private (hvcC/avcC) parse failed; keyframes will lack in-band SPS/PPS"
+        );
+        Vec::new()
+    })
 }
 
 /// PGS `.sup` writer: rebuilds the HDMV segment framing the parser stripped.

src/mux/demux_thread.rs

@@ -7,7 +7,7 @@
 //! With [`crate::sector::PrefetchedSectorSource`] alone, read+decrypt
 //! already runs on a producer thread; the *consumer* (main) thread
 //! still serialises `ts_demuxer.feed` (M2TS parsing) with the codec
-//! parsers. Profiling on the rip1 testbed showed feed at ~37 % and
+//! parsers. Profiling showed feed at ~37 % and
 //! codec parse at ~44 % of consumer wall time — i.e. feed is heavy
 //! enough that pipelining it with parse pays for itself.
 //!

src/mux/disc.rs

@@ -108,11 +108,6 @@ pub struct DiscStream {
     /// inline `decrypt::decrypt_sectors` step. `DecryptKeys::None`
     /// (raw / unencrypted disc) makes the decorator a pass-through.
     reader: DecryptingSectorSource<Box<dyn SectorSource>>,
-    /// Shared decrypt-loss counter, cloned once at construction from
-    /// `reader.decrypt_loss()`. `lost_bytes()` loads it directly so the
-    /// per-frame hot path performs no per-call `Arc::clone` (matching the
-    /// `PipelinedPesStream` pattern).
-    decrypt_loss: std::sync::Arc<std::sync::atomic::AtomicU64>,
     title: DiscTitle,
     /// Mirror of the keys handed in at construction. The decorator
     /// owns the cryptographic state; this field is kept for
@@ -242,8 +237,7 @@ impl DiscStream {
         // concern, never conceal / re-fetch / count as loss (fail loud only on a
         // genuine can't-decrypt). DiscStream is a decode/mux stream (live-drive
         // single-pass / direct), never the ciphertext-preserving sweep.
-        let mut reader =
-            DecryptingSectorSource::new(reader, decrypt_keys.clone()).tolerate_decrypt_loss();
+        let mut reader = DecryptingSectorSource::new(reader, decrypt_keys.clone());
 
         // Wrong-substream fix (Silence-of-the-Lambs): re-route the title's
         // declared AC-3 audio onto the physically-correct `0x8x` sub-streams by
@@ -294,9 +288,6 @@ impl DiscStream {
         // the decorator is a pass-through). Reset the unit base the probe read
         // advanced so the first fill_extents read starts cleanly.
         reader.set_unit_base(0);
-        // Clone the shared loss counter once here so `lost_bytes()` never
-        // clones an Arc per frame on the mux hot path.
-        let decrypt_loss = reader.decrypt_loss();
 
         // B1 resync gates: one per stream, video flagged so the gate only
         // drop-to-keyframes video (audio/subtitle always admit). Computed before
@@ -312,7 +303,6 @@ impl DiscStream {
 
         Self {
             reader,
-            decrypt_loss,
             title,
             decrypt_keys,
             unit_align,
@@ -1004,14 +994,12 @@ impl crate::pes::Stream for DiscStream {
     }
 
     fn lost_bytes(&self) -> u64 {
-        // Read-error zero-fill loss (counted in fill_extents) PLUS decrypt-time
-        // loss — bytes of scrambled AACS units the decorator could not decrypt
-        // and passed through still encrypted (the TS assembler silently drops
-        // them). Both are real missing content the abort gate must see; without
-        // the decrypt term a partial key failure reports lost_bytes=0 and a rip
-        // missing segments passes even under abort_on_lost_secs=0.
+        // Read-error zero-fill loss (counted in fill_extents) — real missing
+        // content the abort gate must see. There is no decrypt-loss term: the
+        // decrypt path passes bad-encoded/undecryptable units through (a broken-TS
+        // unit is the muxer's concern, and a missing key is indistinguishable from
+        // bad authoring here), so only physical read loss is reported.
         self.lost_bytes
-            .saturating_add(self.decrypt_loss.load(std::sync::atomic::Ordering::Relaxed))
     }
 }
 
@@ -1490,6 +1478,7 @@ mod tests {
         let keys = crate::decrypt::DecryptKeys::Aacs {
             unit_keys: vec![(0, [0u8; 16])],
             read_data_key: None,
+            format: crate::disc::ContentFormat::BdTs,
         };
         let mut stream = DiscStream::new(Box::new(reader), title, keys, 8, ContentFormat::BdTs);
         stream.skip_errors = true;

src/mux/mkv.rs

@@ -785,23 +785,35 @@ fn block_ts(is_video: bool, prev: Option<i64>, pts_ticks: i64) -> i64 {
 
 /// Encode a Matroska track number as an EBML VINT into a stack buffer,
 /// returning the buffer and the used length. Track numbers are small (1-based,
-/// a handful of tracks), so 1 byte covers `< 0x80` and 2 bytes covers the rest;
-/// no heap allocation, called once per block on the mux hot path.
+/// a handful of tracks), so 1 byte covers `< 0x80`, 2 bytes covers `< 0x4000`,
+/// and 3 bytes covers `< 0x20_0000`; no heap allocation, called once per block
+/// on the mux hot path.
 ///
-/// The 2-byte form holds 14 payload bits (max 0x3FFF). The `debug_assert`
-/// guards the 0x4000 bound: at or above it, `(track_num >> 8)` is >= 0x40 and
-/// OR-ing the 0x40 length marker would clobber it, corrupting the track
-/// number. Not reachable today (track numbers are `i+1` over a few streams),
-/// so this documents the bound rather than handling 3-byte VINTs.
-fn track_vint(track_num: usize) -> ([u8; 2], usize) {
+/// Each width uses a marker bit that must NOT collide with the payload's top
+/// byte: the 1-byte marker is 0x80 (7 payload bits), the 2-byte marker 0x40
+/// (14 payload bits), the 3-byte marker 0x20 (21 payload bits). Handling all
+/// three in RELEASE (not just `debug_assert`) means an out-of-2-byte-range
+/// track number can never silently clobber the marker bit and corrupt the
+/// block. Real discs never approach even the 2-byte range; the 21-bit ceiling
+/// is an absurd upper bound kept as a `debug_assert`.
+fn track_vint(track_num: usize) -> ([u8; 3], usize) {
     if track_num < 0x80 {
-        ([(track_num as u8) | 0x80, 0], 1)
+        ([(track_num as u8) | 0x80, 0, 0], 1)
+    } else if track_num < 0x4000 {
+        ([0x40 | ((track_num >> 8) as u8), track_num as u8, 0], 2)
     } else {
         debug_assert!(
-            track_num < 0x4000,
-            "track number {track_num} exceeds the 14-bit 2-byte EBML VINT range"
+            track_num < 0x20_0000,
+            "track number {track_num} exceeds the 21-bit 3-byte EBML VINT range"
         );
-        ([0x40 | ((track_num >> 8) as u8), track_num as u8], 2)
+        (
+            [
+                0x20 | ((track_num >> 16) as u8),
+                (track_num >> 8) as u8,
+                track_num as u8,
+            ],
+            3,
+        )
     }
 }
 
@@ -3507,7 +3519,7 @@ mod tests {
     }
 
     #[test]
-    fn track_vint_encodes_one_and_two_byte_forms() {
+    fn track_vint_encodes_one_two_and_three_byte_forms() {
         // 1-byte form for track numbers < 0x80, high bit set.
         let (b, n) = track_vint(1);
         assert_eq!(&b[..n], &[0x81]);
@@ -3518,6 +3530,12 @@ mod tests {
         assert_eq!(&b[..n], &[0x40, 0x80]);
         let (b, n) = track_vint(0x3FFF);
         assert_eq!(&b[..n], &[0x7F, 0xFF]);
+        // 3-byte form at/above 0x4000, 0x20 length marker in the top byte —
+        // handled in RELEASE (no silent marker-bit clobber), not just debug.
+        let (b, n) = track_vint(0x4000);
+        assert_eq!(&b[..n], &[0x20, 0x40, 0x00]);
+        let (b, n) = track_vint(0x1F_FFFF);
+        assert_eq!(&b[..n], &[0x3F, 0xFF, 0xFF]);
     }
 
     // ============================================================

src/mux/mkvstream.rs

@@ -1016,7 +1016,11 @@ fn parse_track(
                     arem = arem.saturating_sub(ahlen as u64 + as_);
                     match aid {
                         ebml::SAMPLING_FREQUENCY => sr = ebml::read_float_val(r, as_ as usize)?,
-                        ebml::CHANNELS => ch = read_uint_bounded(r, as_)? as u8,
+                        // Clamp instead of `as u8`: a foreign/corrupt MKV with a
+                        // CHANNELS value that is a multiple of 256 would truncate to
+                        // 0 (an invalid channel count) on a bare cast. Saturate to
+                        // u8::MAX so an absurd count degrades to "many", never to 0.
+                        ebml::CHANNELS => ch = read_uint_bounded(r, as_)?.min(u8::MAX as u64) as u8,
                         _ => {
                             skip_bytes(r, as_)?;
                         }

src/mux/pipelined_stream.rs

@@ -56,14 +56,6 @@ pub struct PipelinedPesStream {
     /// `std::env::var_os` takes a process-wide lock, so the per-batch /
     /// per-poll reads it replaces were needless hot-path overhead.
     skip_parse: bool,
-    /// Cumulative bytes of scrambled AACS units the producer's decrypt step
-    /// could not decrypt — silent decrypt loss the demux drops without a sync.
-    /// Shared with the producer thread's [`DecryptingSectorSource`]
-    /// (`crate::sector::DecryptingSectorSource::decrypt_loss`). Surfaced through
-    /// [`Stream::lost_bytes`] so the file-backed mux abort gate sees a partial
-    /// decrypt failure instead of reporting a perfect rip. `None` for pipelines
-    /// with no AACS decrypt step (e.g. the M2TS byte-stream path).
-    decrypt_loss: Option<std::sync::Arc<std::sync::atomic::AtomicU64>>,
     /// Count of dropped DVD navigation packets (private_stream_2, 0xBF). These
     /// are expected on every disc; instead of a per-packet WARN they're tallied
     /// and summarised once at EOF.
@@ -134,7 +126,6 @@ impl PipelinedPesStream {
             pending_frames: std::collections::VecDeque::new(),
             eof: false,
             skip_parse: std::env::var_os("FREEMKV_SKIP_PARSE").is_some(),
-            decrypt_loss: None,
             dropped_nav_packets: 0,
             resync,
             is_video,
@@ -142,20 +133,6 @@ impl PipelinedPesStream {
         }
     }
 
-    /// Attach the producer's decrypt-loss counter so [`Stream::lost_bytes`]
-    /// reports bytes of scrambled AACS units that could not be decrypted (and
-    /// were therefore silently dropped downstream). Obtained from the
-    /// producer's `DecryptingSectorSource::decrypt_loss()` before it is moved
-    /// into the prefetch thread. The M2TS / no-decrypt pipelines leave this
-    /// unset.
-    pub(crate) fn with_decrypt_loss(
-        mut self,
-        loss: std::sync::Arc<std::sync::atomic::AtomicU64>,
-    ) -> Self {
-        self.decrypt_loss = Some(loss);
-        self
-    }
-
     /// Pull one batch of `PesPacket`s from the demux thread, run
     /// codec parse on each, enqueue resulting `PesFrame`s on
     /// `pending_frames`. Returns Ok(true) on success, Ok(false) on
@@ -464,17 +441,9 @@ impl Stream for PipelinedPesStream {
             .and_then(|(_, parser)| parser.codec_private())
     }
 
-    fn lost_bytes(&self) -> u64 {
-        // The file-backed highway has no read-error zero-fill term (resolve
-        // tracks read loss separately), but the producer's decrypt step can
-        // pass scrambled units through undecrypted — silent loss the demux
-        // drops. Surface that so the mux abort gate sees a partial AACS/CSS
-        // decrypt failure rather than reporting a perfect rip.
-        self.decrypt_loss
-            .as_ref()
-            .map(|c| c.load(std::sync::atomic::Ordering::Relaxed))
-            .unwrap_or(0)
-    }
+    // `lost_bytes` uses the trait default (0): the file-backed highway has no
+    // read-error zero-fill term (resolve/mapfile tracks physical read loss
+    // separately) and the decrypt path no longer reports a decrypt-loss term.
 }
 
 #[cfg(test)]

src/mux/resolve.rs

@@ -391,11 +391,11 @@ pub fn input(url: &str, opts: &InputOptions) -> io::Result<Box<dyn crate::pes::S
             let title = disc.titles[idx].clone();
             let format = disc.content_format;
             // ISO file: 8192-sector batch (16 MiB at 2048 B/sector) —
-            // sequential read from fast storage, no bad sectors. Measured
-            // optimum on the rip1 testbed; bumping to 16384 sectors (32 MiB)
-            // regressed (more cache pressure, longer per-batch latency starves
-            // the consumer between iterations). Physical drives keep smaller
-            // batches for adaptive error handling.
+            // sequential read from fast storage, no bad sectors. Empirically
+            // optimal; bumping to 16384 sectors (32 MiB) regressed (more cache
+            // pressure, longer per-batch latency starves the consumer between
+            // iterations). Physical drives keep smaller batches for adaptive
+            // error handling.
             const ISO_MUX_BATCH_SECTORS: u16 = 8192;
 
             // Pass `DecryptKeys::None` to the decrypt decorator when
@@ -621,7 +621,8 @@ fn build_demux_state(title: &DiscTitle, format: ContentFormat) -> DemuxState {
 /// - `fetch`: optional fresh-key-on-failure callback (see
 ///   [`crate::sector::KeyFetch`]). When a unit no held key decrypts, the
 ///   decrypt decorator hands that ciphertext to `fetch` and adds any key it
-///   returns. `None` keeps the prior behaviour (the unit is counted as loss).
+///   returns, then re-decrypts. `None` means no mid-stream key recovery — the
+///   unit's best-effort bytes pass through to the muxer as-is.
 // Eight reader/title/keys/tuning/callback params is inherent to the mux entry
 // point; grouping them into a struct would only move the same fields around.
 #[allow(clippy::too_many_arguments)]
@@ -647,19 +648,25 @@ pub fn build_iso_pipeline<S: SectorSource + Send + 'static>(
     };
     // MUX path: read > decrypt > mux. The decrypt seam applies the CPS unit key and
     // passes the bytes to the muxer; a unit that decrypts to broken TS is the
-    // muxer's problem, not a decrypt failure, so the mux never conceals, re-fetches
-    // a key, or counts it as loss — it fails only when it genuinely can't decrypt
-    // (no key / misaligned unit). The `fetch` key-recovery seam is a rip/verify
-    // concern (Disc::sweep / Disc::patch), deliberately NOT installed on the mux:
-    // key recovery happens up front, and the mux never re-asks mid-stream.
+    // muxer's problem, not a decrypt failure, so the mux never conceals a unit or
+    // counts it as loss.
     let mut decrypting =
-        crate::sector::DecryptingSectorSource::new(Box::new(reader) as Box<dyn SectorSource>, keys)
-            .tolerate_decrypt_loss();
-    let _ = &fetch; // rip/verify key-recovery seam; the mux does not consume it
-    // Loss counter: the mux does not tally broken-TS units (the muxer handles them),
-    // so for a keyed disc this stays 0; it still surfaces via `lost_bytes()` for the
-    // abort gate, which now reflects only a genuine can't-decrypt.
-    let decrypt_loss = decrypting.decrypt_loss();
+        crate::sector::DecryptingSectorSource::new(Box::new(reader) as Box<dyn SectorSource>, keys);
+    // Install the fresh-key-on-failure callback (if the app supplied one). This is
+    // how multi-CPS is muxed: each CPS unit's key is fetched when the mux reaches a
+    // unit no held key opens — "get the key when we need it." It fires only on a
+    // genuine miss: now that key selection is accurate (`is_clean_ts`), a unit that
+    // decrypted correctly but has bad-encoded TS is NOT a miss, so this no longer
+    // storms the key source the way the old TS supermajority gate did.
+    if let Some(cb) = fetch {
+        decrypting = decrypting.with_key_fetch(cb);
+    }
+    // Loss-counter handle. The mux does NOT tally decrypt-quality misses: a
+    // broken-TS unit is the muxer's concern, and a missing key is an up-front
+    // resolve failure — indistinguishable from bad authoring at this seam, so
+    // counting it would false-abort a bad-encoded-but-decryptable disc. A genuine
+    // can't-decrypt surfaces as `Err`; `lost_bytes()` reflects physical read loss
+    // only (there is no decrypt-loss term to fold in).
 
     // Wrong-substream fix (Silence-of-the-Lambs): before the prefetcher takes
     // the reader, probe the feature head through the (plaintext) decrypting
@@ -685,10 +692,13 @@ pub fn build_iso_pipeline<S: SectorSource + Send + 'static>(
     let (demux_thread, demux_rx) =
         super::demux_thread::DemuxThread::spawn_zero_copy(rx, recycle_tx, shell, halt, ts, ps)
             .map_err(|e| -> io::Error { e.into() })?;
-    Ok(
-        PipelinedPesStream::new(demux_thread, demux_rx, title, parsers, pid_to_track)
-            .with_decrypt_loss(decrypt_loss),
-    )
+    Ok(PipelinedPesStream::new(
+        demux_thread,
+        demux_rx,
+        title,
+        parsers,
+        pid_to_track,
+    ))
 }
 
 /// Assemble the M2TS file mux pipeline (read → demux → parse) for a

src/mux/ts.rs

@@ -12,9 +12,11 @@ use crate::consts::TS_PACKET_BYTES;
 
 /// TS sync byte.
 const SYNC_BYTE: u8 = 0x47;
-/// MPEG-TS null-packet PID (0x1FFF). Carries no elementary stream; the P3
-/// concealment fill emits null packets on this PID, tagged with an
-/// adaptation-field discontinuity_indicator to signal a concealed gap.
+/// MPEG-TS null-packet PID (0x1FFF). Carries no elementary stream. The demuxer
+/// still recognises a `0x1FFF` packet with an adaptation-field
+/// discontinuity_indicator as a concealed-gap loss signal, but the in-tree WRITER
+/// that emitted these (the removed NULL-TS concealment fill) is gone — the mux no
+/// longer conceals; only externally-authored markers reach this path now.
 const NULL_PID: u16 = 0x1FFF;
 
 /// A reassembled PES packet with timestamp info.
@@ -34,8 +36,10 @@ pub struct PesPacket {
     pub source: Option<crate::pes::SourcePos>,
     /// True when one or more packets for this stream were lost before this PES —
     /// a continuity break (CC gap or adaptation-field discontinuity_indicator) on
-    /// a tracked PID, or the CC-independent concealment marker the mux emits when
-    /// it replaces an undecryptable unit with NULL-TS packets (P3/A2). This PES is
+    /// a tracked PID, or a CC-independent NULL-TS concealment marker (P3/B1). NOTE:
+    /// the mux no longer emits such markers (the concealment writer was removed);
+    /// this now flags only real discontinuities and externally-authored markers.
+    /// This PES is
     /// the FIRST whose data is entirely after the gap: a mid-frame loss drops the
     /// truncated partial and flags the next complete PES; a loss landing on a PES
     /// boundary flags the PES STARTING after it (never the one just flushed). So
@@ -200,7 +204,7 @@ impl PesAssembler {
 /// BD Transport Stream demuxer.
 pub struct TsDemuxer {
     assemblers: Vec<PesAssembler>,
-    pid_index: Vec<i16>, // PID → index into assemblers, -1 = not tracked
+    pid_index: Vec<i32>, // PID → index into assemblers, -1 = not tracked
     remainder: Vec<u8>,  // leftover bytes from previous feed() call
     /// Absolute source byte offset of the NEXT byte to be fed — the running
     /// base that turns an in-buffer packet offset into a source position.
@@ -224,20 +228,17 @@ impl TsDemuxer {
     /// limits. Empty `pids` yields max_pid 0; the floor still produces a
     /// valid (wholly-unused) table.
     pub fn new(pids: &[u16]) -> Self {
-        // The PID→assembler index is stored as i16 (-1 = untracked), so a
-        // 32768th+ tracked PID would truncate to a negative value and be
-        // silently treated as untracked. Callers pass a handful of PIDs
-        // (BD-TS has at most ~8192), so this is a programmer-error guard.
-        debug_assert!(
-            pids.len() <= i16::MAX as usize,
-            "TsDemuxer: too many PIDs for an i16 index table"
-        );
+        // The PID→assembler index is stored as i32 (-1 = untracked). PIDs are
+        // u16 (≤ 65535) and the assembler index `i` is bounded by the number of
+        // distinct PIDs (≤ 65536), both far below i32::MAX, so `i as i32` can
+        // never truncate to a negative value and be mis-read as untracked —
+        // unlike an i16 table, this is safe in RELEASE, not just under debug.
         let max_pid = pids.iter().copied().max().unwrap_or(0) as usize;
         let table_size = (max_pid + 1).max(8192);
-        let mut pid_index = vec![-1i16; table_size];
+        let mut pid_index = vec![-1i32; table_size];
         let mut assemblers = Vec::with_capacity(pids.len());
         for (i, &pid) in pids.iter().enumerate() {
-            pid_index[pid as usize] = i as i16;
+            pid_index[pid as usize] = i as i32;
             assemblers.push(PesAssembler::new(pid));
         }
         Self {
@@ -368,10 +369,13 @@ impl TsDemuxer {
         let pusi = ts[1] & 0x40 != 0; // Payload Unit Start Indicator
         let adaptation = (ts[3] >> 4) & 0x03;
 
-        // P3/B1 CONCEALMENT MARKER. The decrypt layer fills an undecryptable
-        // aligned unit with NULL-TS packets (PID 0x1FFF) that carry an
-        // adaptation-field discontinuity_indicator (see `aacs::content::fill_null_ts_unit`).
-        // This is the authoritative loss signal — unlike a tracked PID's 4-bit
+        // P3/B1 CONCEALMENT MARKER: a NULL-TS packet (PID 0x1FFF) carrying an
+        // adaptation-field discontinuity_indicator. NOTE: the in-tree writer that
+        // laid these down on an undecryptable unit was removed with the pure-decrypt
+        // passthrough change (the mux no longer conceals), so this recognition now
+        // only fires on externally-authored markers — a candidate for removal with
+        // the rest of the retired concealment path.
+        // As a loss signal it is CC-INDEPENDENT — unlike a tracked PID's 4-bit
         // continuity_counter it is CC-INDEPENDENT, so it survives a loss that is
         // an exact multiple of 16 packets and a loss at the very start of a PID
         // (no prior CC to diff against). The decrypt layer cannot know which
@@ -1057,7 +1061,7 @@ mod tests {
 
     /// One 192-byte BD source packet that is a B1 concealment marker: a PID-0x1FFF
     /// null packet carrying the adaptation-field discontinuity_indicator (the byte
-    /// shape `fill_null_ts_unit` writes for every packet of a concealed unit).
+    /// shape of a concealed-unit packet).
     fn null_marker_packet() -> Vec<u8> {
         let mut pkt = vec![0u8; BD_SOURCE_PACKET_BYTES];
         pkt[4] = SYNC_BYTE; // 0x47

src/sector/mod.rs

@@ -129,6 +129,10 @@ impl SectorSource for Box<dyn SectorSource> {
     fn set_speed(&mut self, kbs: u16) {
         (**self).set_speed(kbs)
     }
+
+    fn set_unit_base(&mut self, lba: u32) {
+        (**self).set_unit_base(lba)
+    }
 }
 
 impl SectorSource for &mut (dyn SectorSource + '_) {
@@ -160,6 +164,10 @@ impl SectorSource for &mut (dyn SectorSource + '_) {
     fn set_speed(&mut self, kbs: u16) {
         (**self).set_speed(kbs)
     }
+
+    fn set_unit_base(&mut self, lba: u32) {
+        (**self).set_unit_base(lba)
+    }
 }
 
 /// Write 2048-byte sectors to a disc image or composed sink.
@@ -181,7 +189,7 @@ pub trait SectorSink: Send {
 }
 
 pub use crate::io::file_sector_source::FileSectorSource;
-pub use decrypting::{DECRYPT_VERIFY_READ, DecryptingSectorSource, KeyFetch};
+pub use decrypting::{DecryptingSectorSource, KeyFetch};
 pub use file::FileSectorSink;
 pub use prefetched::PrefetchedSectorSource;
 
@@ -198,23 +206,33 @@ mod tests {
         capacity: u32,
         reads: Arc<Mutex<Vec<(u32, u16, bool)>>>,
         speeds: Arc<Mutex<Vec<u16>>>,
+        unit_bases: Arc<Mutex<Vec<u32>>>,
     }
 
-    /// A `Spy` under test plus the handles recording its reads and speed sets.
-    type SpyHarness = (Spy, Arc<Mutex<Vec<(u32, u16, bool)>>>, Arc<Mutex<Vec<u16>>>);
+    /// A `Spy` under test plus the handles recording its reads, speed sets,
+    /// and unit-base sets.
+    type SpyHarness = (
+        Spy,
+        Arc<Mutex<Vec<(u32, u16, bool)>>>,
+        Arc<Mutex<Vec<u16>>>,
+        Arc<Mutex<Vec<u32>>>,
+    );
 
     impl Spy {
         fn new(capacity: u32) -> SpyHarness {
             let reads = Arc::new(Mutex::new(Vec::new()));
             let speeds = Arc::new(Mutex::new(Vec::new()));
+            let unit_bases = Arc::new(Mutex::new(Vec::new()));
             (
                 Self {
                     capacity,
                     reads: reads.clone(),
                     speeds: speeds.clone(),
+                    unit_bases: unit_bases.clone(),
                 },
                 reads,
                 speeds,
+                unit_bases,
             )
         }
     }
@@ -238,6 +256,16 @@ mod tests {
         fn set_speed(&mut self, kbs: u16) {
             self.speeds.lock().unwrap().push(kbs);
         }
+        fn set_unit_base(&mut self, lba: u32) {
+            self.unit_bases.lock().unwrap().push(lba);
+        }
+    }
+
+    /// Call `set_unit_base` through a generic `S: SectorSource` bound — this is
+    /// the path that actually exercises the `Box<dyn>` / `&mut dyn` FORWARDING
+    /// impls (a direct call on a `dyn` value dispatches via the vtable instead).
+    fn set_unit_base_generic<S: SectorSource>(mut s: S, base: u32) {
+        s.set_unit_base(base);
     }
 
     /// The default `capacity_sectors` is 0 (unknown). Grounding: trait
@@ -286,7 +314,7 @@ mod tests {
     /// Box<dyn SectorSource>` forwarding bodies.
     #[test]
     fn boxed_dyn_forwards_all_methods() {
-        let (spy, reads, speeds) = Spy::new(777);
+        let (spy, reads, speeds, unit_bases) = Spy::new(777);
         let mut boxed: Box<dyn SectorSource> = Box::new(spy);
 
         assert_eq!(boxed.capacity_sectors(), 777, "capacity must forward");
@@ -308,24 +336,46 @@ mod tests {
             vec![5400],
             "set_speed must forward"
         );
+
+        // set_unit_base through the generic bound exercises the forwarding impl
+        // (a direct `boxed.set_unit_base()` would vtable-dispatch instead). A
+        // missing forwarding body would silently no-op and record nothing.
+        set_unit_base_generic(boxed, 64);
+        assert_eq!(
+            *unit_bases.lock().unwrap(),
+            vec![64],
+            "set_unit_base must forward through Box<dyn>"
+        );
     }
 
-    /// `&mut dyn SectorSource` must likewise forward all three methods.
+    /// `&mut dyn SectorSource` must likewise forward every method.
     /// Grounding: `impl SectorSource for &mut (dyn SectorSource + '_)`.
     #[test]
     fn mut_ref_dyn_forwards_all_methods() {
-        let (mut spy, reads, speeds) = Spy::new(123);
-        let r: &mut dyn SectorSource = &mut spy;
+        let (mut spy, reads, speeds, unit_bases) = Spy::new(123);
 
-        assert_eq!(r.capacity_sectors(), 123);
+        {
+            let r: &mut dyn SectorSource = &mut spy;
+            assert_eq!(r.capacity_sectors(), 123);
 
-        let mut buf = vec![0u8; 2 * 2048];
-        let n = r.read_sectors(7, 2, &mut buf, false).unwrap();
-        assert_eq!(n, 2 * 2048);
+            let mut buf = vec![0u8; 2 * 2048];
+            let n = r.read_sectors(7, 2, &mut buf, false).unwrap();
+            assert_eq!(n, 2 * 2048);
 
-        r.set_speed(8800);
+            r.set_speed(8800);
+        }
+
+        // Pass `&mut dyn` as a generic S so the forwarding impl's set_unit_base
+        // is the one under test, not the vtable path.
+        let r2: &mut dyn SectorSource = &mut spy;
+        set_unit_base_generic(r2, 128);
 
         assert_eq!(*reads.lock().unwrap(), vec![(7, 2, false)]);
         assert_eq!(*speeds.lock().unwrap(), vec![8800]);
+        assert_eq!(
+            *unit_bases.lock().unwrap(),
+            vec![128],
+            "set_unit_base must forward through &mut dyn"
+        );
     }
 }

src/sector/prefetched.rs

@@ -252,11 +252,14 @@ impl PrefetchedSectorSource {
                         };
                         if bytes <= buf.capacity() {
                             // Re-expose `bytes` without zero-filling pages that
-                            // `read_sectors` is about to overwrite. The enclosing
-                            // capacity guard makes the `set_len` provably sound even
-                            // if a recycled buffer ever comes back smaller than the
-                            // `vec![0u8; batch_bytes]` it was born with.
-                            debug_assert!(bytes <= buf.capacity(), "set_len exceeds capacity");
+                            // `read_sectors` is about to overwrite. Sound because the
+                            // enclosing `bytes <= capacity` guard bounds the length,
+                            // and every byte below `capacity` is physically
+                            // initialised: buffers are born `vec![0u8; batch_bytes]`
+                            // and only ever grown via `resize(_, 0)`, so a recycled
+                            // buffer that came back shorter (consumer `truncate`)
+                            // still has initialised backing storage under `set_len`,
+                            // which `read_sectors` then overwrites before any read.
                             unsafe { buf.set_len(bytes) };
                         } else {
                             buf.resize(bytes, 0);

src/sector/recovery.rs

@@ -135,6 +135,12 @@ fn aacs_fetch_step(
         return prev_dropped;
     }
     let unit_len = crate::aacs::content::ALIGNED_UNIT_LEN;
+    // Container of this disc's content — travels with the keys; drives the
+    // encrypted-flag / structure check below (TS vs PS).
+    let format = match &*keys {
+        DecryptKeys::Aacs { format, .. } => *format,
+        _ => crate::disc::ContentFormat::BdTs,
+    };
     // Gather up to MAX_FETCH_SAMPLES units the current pool did NOT open. Detect
     // them on the post-decrypt TARGET (a failed unit stays TS-destroyed; an opened
     // one is now clean TS and is skipped), but SAMPLE the matching on-disc
@@ -146,7 +152,7 @@ fn aacs_fetch_step(
         .chunks_exact(unit_len)
         .zip(ciphertext.chunks_exact(unit_len))
     {
-        if crate::aacs::content::aacs_unit_needs_decrypt(t) {
+        if crate::aacs::content::aacs_unit_needs_decrypt(t, format) {
             samples.push(c.to_vec());
             if samples.len() >= MAX_FETCH_SAMPLES {
                 break;
@@ -256,6 +262,7 @@ mod tests {
         let mut keys = DecryptKeys::Aacs {
             unit_keys: vec![],
             read_data_key: None,
+            format: crate::disc::ContentFormat::BdTs,
         };
         let cipher = buf.clone();
         let out = r(&mut buf, &cipher, &mut keys, &ctx(0, 6144));
@@ -279,6 +286,7 @@ mod tests {
         let mut keys = DecryptKeys::Aacs {
             unit_keys: vec![],
             read_data_key: None,
+            format: crate::disc::ContentFormat::BdTs,
         };
         let cipher = buf.clone();
         r(&mut buf, &cipher, &mut keys, &ctx(0, ALIGNED_UNIT_LEN));
@@ -304,6 +312,7 @@ mod tests {
         let mut keys = DecryptKeys::Aacs {
             unit_keys: vec![],
             read_data_key: None,
+            format: crate::disc::ContentFormat::BdTs,
         };
         let mut buf = scrambled_unit(0x44);
         let cipher = buf.clone();
@@ -330,6 +339,7 @@ mod tests {
         let mut keys = DecryptKeys::Aacs {
             unit_keys: vec![],
             read_data_key: None,
+            format: crate::disc::ContentFormat::BdTs,
         };
         // Distinct ciphertext each time so the dry-set never short-circuits; only
         // the internal call budget should stop the fetch. The closure self-limits,

src/udf.rs

@@ -1790,6 +1790,57 @@ mod tests {
         assert!(inf[2048..].iter().all(|&b| b == 0xBB));
     }
 
+    #[test]
+    fn read_aacs_inputs_falls_through_to_hddvd_any_dir() {
+        // HD DVD keeps its AACS material under /ANY!/ (VTKF000.AACS title-key
+        // file + MKBROM.AACS), NOT /AACS/Unit_Key_RO.inf + /AACS/MKB_RO.inf. The
+        // role-based candidate lists must fall through to the /ANY!/ files with
+        // NO disc-type branch, so the online keyserver POST carries the HD DVD
+        // title-key file (magic "DVD_HD_V_TKF") as inf_b64 + MKBROM as mkb_b64 —
+        // the server then classifies the disc as HD DVD by that magic.
+        let any = DirEntry {
+            name: "ANY!".to_string(),
+            is_dir: true,
+            meta_lba: 0,
+            size: 0,
+            entries: vec![
+                file_entry("VTKF000.AACS", 5, 2048),
+                file_entry("MKBROM.AACS", 7, 2048),
+            ],
+        };
+        let root = DirEntry {
+            name: String::new(),
+            is_dir: true,
+            meta_lba: 0,
+            size: 0,
+            entries: vec![any], // deliberately NO /AACS/ dir
+        };
+        let mut reader = MapReader::new();
+        // VTKF000.AACS: one extent whose content opens with the HD DVD magic.
+        let mut vtkf = [0u8; 2048];
+        vtkf[..12].copy_from_slice(b"DVD_HD_V_TKF");
+        reader.put(5, build_efe_long(2048, &[(0, 2048, 10)]));
+        reader.put(10, vtkf);
+        // MKBROM.AACS: one extent with a type-0x10 AACS-1.0 (HD DVD) version record.
+        let mut mkb = [0u8; 2048];
+        mkb[..12].copy_from_slice(&[
+            0x10, 0x00, 0x00, 0x0C, 0x00, 0x04, 0x10, 0x03, 0x00, 0x00, 0x00, 0x03,
+        ]);
+        reader.put(7, build_efe_long(2048, &[(0, 2048, 50)]));
+        reader.put(50, mkb);
+
+        let fs = fs_with(0, 0, root);
+        let (inf, _mkb, _version) =
+            crate::disc::Disc::read_aacs_inputs_from_reader(&mut reader, &fs)
+                .expect("read_aacs_inputs must source the HD DVD /ANY!/ files");
+        assert_eq!(
+            &inf[..12],
+            b"DVD_HD_V_TKF",
+            "inf must be the HD DVD VTKF (its magic), sourced from /ANY!/ via the \
+             candidate fall-through — not /AACS/Unit_Key_RO.inf"
+        );
+    }
+
     #[test]
     fn merge_ranges_saturates_near_u32_max() {
         // Adjacent ranges near u32::MAX must not panic (debug) or wrap.