Magic-number/taxonomy pass: central wire-format + sector + unit consts

- libfreemkv::consts: coding_type::* (ES coding-type bytes), pes_stream_id::*
  + PAYLOAD_RANGE, SECTOR_BYTES (usize) + SECTOR_BYTES_U64 (offset math)
- replace bare wire-code/sector literals across disc, mpls, clpi, labels,
  m2ts_mux, ps, tsmux, file_sector_source, extract
- remove two unreachable secondary-stream match arms in mpls parse_stream_entry

src/clpi.rs

@@ -6,7 +6,7 @@
 //!
 //! Reference: https://github.com/lw/BluRay/wiki/CLPI
 
-use crate::consts::{BD_SOURCE_PACKET_BYTES, SECTOR_BYTES};
+use crate::consts::{BD_SOURCE_PACKET_BYTES, SECTOR_BYTES_U64};
 use crate::disc::Extent;
 use crate::error::{Error, Result};
 
@@ -175,8 +175,8 @@ impl ClipInfo {
         // a sub-sector-aligned range still spans every sector it touches.
         let start_byte = start_spn as u64 * BD_SOURCE_PACKET_BYTES as u64;
         let end_byte = end_spn as u64 * BD_SOURCE_PACKET_BYTES as u64;
-        let start_sector = (start_byte / SECTOR_BYTES as u64) as u32;
-        let end_sector = end_byte.div_ceil(SECTOR_BYTES as u64) as u32;
+        let start_sector = (start_byte / SECTOR_BYTES_U64) as u32;
+        let end_sector = end_byte.div_ceil(SECTOR_BYTES_U64) as u32;
 
         vec![Extent {
             start_lba: start_sector, // relative to m2ts file start
@@ -261,6 +261,7 @@ pub fn parse(data: &[u8]) -> Result<ClipInfo> {
 /// errors because the EP map is the primary CLPI output, and a corrupt
 /// program_info shouldn't break sector-range lookups.
 fn parse_program_info(data: &[u8]) -> Vec<ClpiStream> {
+    use crate::consts::coding_type as c;
     let mut out = Vec::new();
     if data.len() < 6 {
         return out;
@@ -299,16 +300,15 @@ fn parse_program_info(data: &[u8]) -> Vec<ClpiStream> {
             let mut language = String::new();
 
             match coding_type {
-                // Video — MPEG-2 (0x02), H.264 (0x1B), HEVC (0x24)
-                0x02 | 0x1B | 0x24 => {
+                // Video — MPEG-2, H.264, HEVC
+                c::MPEG2_VIDEO | c::H264 | c::HEVC => {
                     if sci.len() >= 2 {
                         video_format = (sci[1] >> 4) & 0x0F;
                         video_rate = sci[1] & 0x0F;
                     }
                 }
-                // Primary audio — LPCM(0x80), AC-3(0x81), DTS(0x82),
-                // TrueHD(0x83), AC-3+(0x84), DTS-HD(0x85), DTS-HD MA(0x86)
-                0x80..=0x86 => {
+                // Primary audio — LPCM, AC-3, DTS, TrueHD, AC-3+, DTS-HD HR, DTS-HD MA
+                c::LPCM..=c::DTS_HD_MA => {
                     if sci.len() >= 2 {
                         audio_format = (sci[1] >> 4) & 0x0F;
                         audio_rate = sci[1] & 0x0F;
@@ -317,8 +317,8 @@ fn parse_program_info(data: &[u8]) -> Vec<ClpiStream> {
                         language = String::from_utf8_lossy(&sci[2..5]).to_string();
                     }
                 }
-                // Secondary audio (0xA1 AC-3+, 0xA2 DTS-HD)
-                0xA1 | 0xA2 => {
+                // Secondary audio (AC-3+ secondary, DTS-HD secondary)
+                c::AC3_PLUS_SECONDARY | c::DTS_HD_SECONDARY => {
                     if sci.len() >= 2 {
                         audio_format = (sci[1] >> 4) & 0x0F;
                         audio_rate = sci[1] & 0x0F;
@@ -327,8 +327,8 @@ fn parse_program_info(data: &[u8]) -> Vec<ClpiStream> {
                         language = String::from_utf8_lossy(&sci[2..5]).to_string();
                     }
                 }
-                // PG (0x90), IG (0x91): coding_type + 3-byte language [+ char_code for PG]
-                0x90 | 0x91 => {
+                // PG, IG: coding_type + 3-byte language [+ char_code for PG]
+                c::PG | c::IG => {
                     if sci.len() >= 4 {
                         language = String::from_utf8_lossy(&sci[1..4]).to_string();
                     }
@@ -1125,8 +1125,8 @@ mod tests {
         let end_spn = big_spn as u64;
         let start_byte = start_spn * BD_SOURCE_PACKET_BYTES as u64;
         let end_byte = end_spn * BD_SOURCE_PACKET_BYTES as u64;
-        let start_sector = (start_byte / SECTOR_BYTES as u64) as u32;
-        let end_sector = end_byte.div_ceil(SECTOR_BYTES as u64) as u32;
+        let start_sector = (start_byte / SECTOR_BYTES_U64) as u32;
+        let end_sector = end_byte.div_ceil(SECTOR_BYTES_U64) as u32;
         assert_eq!(extents[0].start_lba, start_sector);
         assert_eq!(extents[0].sector_count, end_sector - start_sector);
         // Concretely: 0x20000 × 192 / 2048 = 12288 sectors.

src/consts.rs

@@ -8,8 +8,18 @@
 
 /// Bytes per logical sector on every optical medium freemkv reads
 /// (Blu-ray, DVD-Video, CD-ROM Mode 1). Universal — hence unprefixed.
+///
+/// `usize` because its dominant use is buffer sizing and slice indexing, where
+/// Rust *requires* `usize` (`vec![0u8; SECTOR_BYTES]`, `buf.len() < SECTOR_BYTES`).
+/// For byte-offset / capacity arithmetic — which is `u64` because a disc can
+/// exceed 4 GiB — use [`SECTOR_BYTES_U64`] instead of casting at each site.
 pub const SECTOR_BYTES: usize = 2048;
 
+/// [`SECTOR_BYTES`] as `u64`, for byte-offset and capacity arithmetic. The
+/// single `usize → u64` boundary cast lives here, once, so offset math across
+/// the workspace reads as `sectors * SECTOR_BYTES_U64` with no per-site cast.
+pub const SECTOR_BYTES_U64: u64 = SECTOR_BYTES as u64;
+
 /// Bytes per MPEG-2 transport-stream packet. Common to all MPEG-TS, not just
 /// Blu-ray — prefixed by the format, not a disc type.
 pub const TS_PACKET_BYTES: usize = 188;
@@ -31,3 +41,80 @@ pub const TS_PAYLOAD_BYTES: usize = TS_PACKET_BYTES - TS_HEADER_BYTES;
 /// prefixed with the [`BD_TIMESTAMP_PREFIX_BYTES`] arrival-timestamp header.
 /// A BDAV/M2TS construct only — DVD VOBs have no source packets — hence `BD_`.
 pub const BD_SOURCE_PACKET_BYTES: usize = TS_PACKET_BYTES + BD_TIMESTAMP_PREFIX_BYTES;
+
+/// Elementary-stream coding-type codes — the single source of truth for the
+/// byte that identifies a stream's codec.
+///
+/// This is one registry used in two places that share the same value space:
+/// the MPEG-TS PMT `stream_type` (ISO/IEC 13818-1 Table 2-34) and the Blu-ray
+/// STN/CLPI `stream_coding_type` (BD-ROM Part 3). The standardized video codes
+/// (`0x02`, `0x1B`, `0x24`, `0xEA`) are ISO assignments; the `0x80..=0xA2`
+/// audio/graphics codes sit in the ISO user-private range and follow the
+/// Blu-ray Disc Association / ATSC A/52 convention. Because every consumer
+/// reads or writes this single byte, the family is unprefixed — the scope is
+/// "any elementary stream freemkv parses or muxes".
+///
+/// Each constant is `u8`: the spec defines an 8-bit field and the code compares
+/// it directly against a byte read from the buffer, so no casts are needed.
+pub mod coding_type {
+    /// MPEG-2 video (ISO/IEC 13818-1 Table 2-34).
+    pub const MPEG2_VIDEO: u8 = 0x02;
+    /// H.264 / AVC video (ISO/IEC 13818-1 Table 2-34).
+    pub const H264: u8 = 0x1B;
+    /// HEVC / H.265 video (ISO/IEC 13818-1 Table 2-34, 2015 amendment).
+    pub const HEVC: u8 = 0x24;
+    /// SMPTE VC-1 video (BD-ROM convention, ISO user-private range).
+    pub const VC1: u8 = 0xEA;
+
+    /// LPCM audio (BD-ROM convention).
+    pub const LPCM: u8 = 0x80;
+    /// Dolby Digital (AC-3) audio (BD-ROM / ATSC A/52 convention).
+    pub const AC3: u8 = 0x81;
+    /// DTS audio (BD-ROM convention).
+    pub const DTS: u8 = 0x82;
+    /// Dolby TrueHD audio (BD-ROM convention).
+    pub const TRUEHD: u8 = 0x83;
+    /// Dolby Digital Plus (E-AC-3 / AC-3+) audio (BD-ROM convention).
+    pub const AC3_PLUS: u8 = 0x84;
+    /// DTS-HD High Resolution audio (BD-ROM Part 3-1).
+    pub const DTS_HD_HR: u8 = 0x85;
+    /// DTS-HD Master Audio (lossless) (BD-ROM Part 3-1).
+    pub const DTS_HD_MA: u8 = 0x86;
+
+    /// Presentation Graphics — PG subtitle stream (BD-ROM HDMV).
+    pub const PG: u8 = 0x90;
+    /// Interactive Graphics — IG / BD-J menu overlay, NOT a subtitle (BD-ROM HDMV).
+    pub const IG: u8 = 0x91;
+    /// Text subtitle stream (BD-ROM HDMV).
+    pub const TEXT_SUBTITLE: u8 = 0x92;
+
+    /// Secondary Dolby Digital Plus audio (BD-ROM convention).
+    pub const AC3_PLUS_SECONDARY: u8 = 0xA1;
+    /// Secondary DTS-HD audio (lossless MA, not lossy HR) (BD-ROM convention).
+    pub const DTS_HD_SECONDARY: u8 = 0xA2;
+}
+
+/// MPEG PES `stream_id` codes — the byte after the `00 00 01` start-code prefix
+/// that identifies an elementary stream's role in a PES packet (ISO/IEC
+/// 13818-1 Table 2-22). Shared by the program-stream demuxer and the TS/M2TS
+/// muxers, so defined here once. Each is `u8` (matches the byte on the wire).
+pub mod pes_stream_id {
+    /// Video stream (`110x xxxx`; freemkv emits the base id `0xE0`).
+    pub const VIDEO: u8 = 0xE0;
+    /// private_stream_1 — AC-3 / DTS / LPCM / PGS subtitle payloads.
+    pub const PRIVATE_STREAM_1: u8 = 0xBD;
+    /// padding_stream — stuffing bytes only, no payload to demux.
+    pub const PADDING_STREAM: u8 = 0xBE;
+    /// private_stream_2 — DVD navigation (PCI/DSI); carries no muxable ES.
+    pub const PRIVATE_STREAM_2: u8 = 0xBF;
+
+    /// Highest video stream_id — the `110x xxxx` video range tops out at 0xEF.
+    pub const VIDEO_MAX: u8 = 0xEF;
+
+    /// Inclusive range of every PES `stream_id` that carries demuxable payload:
+    /// [`PRIVATE_STREAM_1`] (0xBD) through [`VIDEO_MAX`] (0xEF) — i.e. private
+    /// stream 1/2, padding, MPEG audio (0xC0-0xDF) and video (0xE0-0xEF). The
+    /// pack (0xBA), system-header (0xBB) and program-end (0xB9) codes sit below
+    /// this range and are deliberately excluded: they're structural, not ES.
+    pub const PAYLOAD_RANGE: core::ops::RangeInclusive<u8> = PRIVATE_STREAM_1..=VIDEO_MAX;
+}

src/disc/extract.rs

@@ -24,7 +24,7 @@ use std::io::Write;
 use std::path::{Path, PathBuf};
 use std::sync::atomic::Ordering;
 
-use crate::consts::SECTOR_BYTES;
+use crate::consts::{SECTOR_BYTES, SECTOR_BYTES_U64};
 /// AACS aligned unit = 3 sectors / 6144 bytes. Content reads are issued in
 /// multiples of this so the decrypt step always sees whole units.
 const AACS_UNIT_SECTORS: u32 = 3;
@@ -282,7 +282,7 @@ impl Disc {
                 for &(abs_lba, byte_len) in &pf.extents {
                     extents.push(crate::disc::Extent {
                         start_lba: abs_lba,
-                        sector_count: (byte_len as u64).div_ceil(SECTOR_BYTES as u64) as u32,
+                        sector_count: (byte_len as u64).div_ceil(SECTOR_BYTES_U64) as u32,
                     });
                 }
             }
@@ -467,7 +467,7 @@ fn extract_one_file<S: SectorSource>(
         // the per-extent re-anchoring in the mux read paths
         // (`mux/disc.rs`, `sector/prefetched.rs`). No-op for CSS / None.
         dec.set_unit_base(abs_lba);
-        let sectors = (byte_len as u64).div_ceil(SECTOR_BYTES as u64) as u32;
+        let sectors = (byte_len as u64).div_ceil(SECTOR_BYTES_U64) as u32;
         let mut sector_off: u32 = 0;
         while sector_off < sectors {
             let mut batch = (sectors - sector_off).min(READ_BATCH_SECTORS);

src/disc/mod.rs

@@ -627,28 +627,29 @@ impl Codec {
     ];
 
     pub(crate) fn from_coding_type(ct: u8) -> Self {
+        use crate::consts::coding_type as c;
         match ct {
-            0x24 => Codec::Hevc,
-            0x1B => Codec::H264,
-            0xEA => Codec::Vc1,
-            0x02 => Codec::Mpeg2,
-            0x83 => Codec::TrueHd,
-            0x86 => Codec::DtsHdMa,
-            0x85 => Codec::DtsHdHr,
-            0x82 => Codec::Dts,
-            0x81 => Codec::Ac3,
-            0x84 | 0xA1 => Codec::Ac3Plus,
-            0x80 => Codec::Lpcm,
-            // 0x86 (primary) / 0xA2 (secondary) are the DTS-HD MA
-            // lossless pair, parallel to 0x81/0xA1 for AC-3. 0xA2 is
-            // lossless MA, not lossy HR.
-            0xA2 => Codec::DtsHdMa,
-            // 0x90 = Presentation Graphics (PG / subtitles). 0x91 = Interactive
-            // Graphics (IG / menus) and 0x92 = Text subtitles are distinct HDMV
-            // coding types and are NOT PG subtitle streams; only 0x90 maps to
-            // Pgs. IG (0x91) falls through to Unknown so the PMT/STN walker drops
-            // it rather than surfacing a bogus PGS subtitle track for a menu ES.
-            0x90 => Codec::Pgs,
+            c::HEVC => Codec::Hevc,
+            c::H264 => Codec::H264,
+            c::VC1 => Codec::Vc1,
+            c::MPEG2_VIDEO => Codec::Mpeg2,
+            c::TRUEHD => Codec::TrueHd,
+            c::DTS_HD_MA => Codec::DtsHdMa,
+            c::DTS_HD_HR => Codec::DtsHdHr,
+            c::DTS => Codec::Dts,
+            c::AC3 => Codec::Ac3,
+            c::AC3_PLUS | c::AC3_PLUS_SECONDARY => Codec::Ac3Plus,
+            c::LPCM => Codec::Lpcm,
+            // DTS_HD_MA (primary 0x86) / DTS_HD_SECONDARY (0xA2) are the
+            // DTS-HD MA lossless pair, parallel to AC3/AC3_PLUS_SECONDARY for
+            // AC-3. The secondary code is lossless MA, not lossy HR.
+            c::DTS_HD_SECONDARY => Codec::DtsHdMa,
+            // PG (0x90) = Presentation Graphics (subtitles). IG (0x91, menus)
+            // and TEXT_SUBTITLE (0x92) are distinct HDMV coding types and are
+            // NOT PG subtitle streams; only PG maps to Pgs. IG falls through to
+            // Unknown so the PMT/STN walker drops it rather than surfacing a
+            // bogus PGS subtitle track for a menu ES.
+            c::PG => Codec::Pgs,
             ct => Codec::Unknown(ct),
         }
     }
@@ -5068,8 +5069,8 @@ mod tests {
         let mf = Mapfile::load(&disc.mapfile_for(&iso_path)).expect("load mapfile");
         let good = mf.ranges_with(&[SectorStatus::Finished]);
         let bad_ranges = mf.ranges_with(&[SectorStatus::NonTrimmed]);
-        let disc_bytes = sectors as u64 * 2048;
-        const SEC: u64 = crate::consts::SECTOR_BYTES as u64;
+        const SEC: u64 = crate::consts::SECTOR_BYTES_U64;
+        let disc_bytes = sectors as u64 * SEC;
 
         // The first failing batch starts at LBA 320; everything before it read
         // cleanly and must be Finished.

src/io/file_sector_source/mod.rs

@@ -72,7 +72,7 @@ use std::path::Path;
 use crate::error::{Error, Result};
 use crate::sector::SectorSource;
 
-use crate::consts::SECTOR_BYTES;
+use crate::consts::{SECTOR_BYTES, SECTOR_BYTES_U64};
 
 /// Bytes-read threshold per `posix_fadvise(DONTNEED)` drop on the
 /// read side. Mirrors `WRITEBACK_CHUNK_BYTES` so the read-side page
@@ -134,7 +134,7 @@ impl FileSectorSource {
             .metadata()
             .map_err(|e| Error::IoError { source: e })?
             .len();
-        let sectors = len / SECTOR_BYTES as u64;
+        let sectors = len / SECTOR_BYTES_U64;
         if sectors > u32::MAX as u64 {
             return Err(Error::IsoTooLarge {
                 path: path.to_string_lossy().into_owned(),
@@ -180,7 +180,7 @@ impl SectorSource for FileSectorSource {
         if count == 0 {
             return Ok(0);
         }
-        let offset = lba as u64 * SECTOR_BYTES as u64;
+        let offset = lba as u64 * SECTOR_BYTES_U64;
         self.file
             .seek(SeekFrom::Start(offset))
             .map_err(|e| Error::IoError { source: e })?;
@@ -494,7 +494,7 @@ mod tests {
     #[test]
     fn dontneed_eviction_does_not_affect_data() {
         // 32 MiB default chunk = 16384 sectors; read a bit past it.
-        let total = (READ_DROP_CHUNK_BYTES_DEFAULT / SECTOR_BYTES as u64) as u32 + 64;
+        let total = (READ_DROP_CHUNK_BYTES_DEFAULT / SECTOR_BYTES_U64) as u32 + 64;
         let dir = tempdir().unwrap();
         let path = dir.path().join("drop.iso");
         make_iso(&path, total);

src/labels/mod.rs

@@ -634,6 +634,7 @@ fn append_clpi_orphans(
     reader: &mut dyn SectorSource,
     udf: &UdfFs,
 ) -> usize {
+    use crate::consts::coding_type as c;
     // Index existing labels by PID — but StreamLabel doesn't carry
     // PID. Index by (type, language, codec_hint) tuple instead; this
     // is fuzzier than PID matching but the only signal available
@@ -679,9 +680,11 @@ fn append_clpi_orphans(
             // Interactive Graphics (BD-J menu overlay), NOT a user-facing
             // subtitle — skip it, matching the MPLS path which drops IG.
             let stype = match s.coding_type {
-                0x80..=0x86 | 0xA1 | 0xA2 => StreamLabelType::Audio,
-                0x90 => StreamLabelType::Subtitle,
-                _ => continue, // 0x91 IG / video / unknown — skip
+                c::LPCM..=c::DTS_HD_MA | c::AC3_PLUS_SECONDARY | c::DTS_HD_SECONDARY => {
+                    StreamLabelType::Audio
+                }
+                c::PG => StreamLabelType::Subtitle,
+                _ => continue, // IG / video / unknown — skip
             };
             // Same dedup logic as MPLS: normalize language, build codec
             // hint, check against existing label set.

src/labels/mpls_universal.rs

@@ -227,21 +227,22 @@ pub(crate) fn language_display_name(iso: &str) -> String {
 /// bytes (the table covers everything the spec defines, but unknown
 /// values are still possible on malformed discs).
 pub(crate) fn codec_name(coding_type: u8) -> &'static str {
+    use crate::consts::coding_type as c;
     match coding_type {
-        0x02 => "MPEG-2",
-        0x1B => "H.264",
-        0x24 => "HEVC",
-        0x80 => "LPCM",
-        0x81 => "AC-3",
-        0x82 => "DTS",
-        0x83 => "TrueHD",
-        0x84 => "AC-3+",
-        0x85 => "DTS-HD HR", // BD-ROM Part 3-1: 0x85 = DTS-HD High Resolution
-        0x86 => "DTS-HD MA",
-        0x90 => "PG",
-        0x91 => "IG",
-        0xA1 => "AC-3+ Secondary",
-        0xA2 => "DTS-HD Secondary",
+        c::MPEG2_VIDEO => "MPEG-2",
+        c::H264 => "H.264",
+        c::HEVC => "HEVC",
+        c::LPCM => "LPCM",
+        c::AC3 => "AC-3",
+        c::DTS => "DTS",
+        c::TRUEHD => "TrueHD",
+        c::AC3_PLUS => "AC-3+",
+        c::DTS_HD_HR => "DTS-HD HR", // BD-ROM Part 3-1: 0x85 = DTS-HD High Resolution
+        c::DTS_HD_MA => "DTS-HD MA",
+        c::PG => "PG",
+        c::IG => "IG",
+        c::AC3_PLUS_SECONDARY => "AC-3+ Secondary",
+        c::DTS_HD_SECONDARY => "DTS-HD Secondary",
         _ => "",
     }
 }

src/mpls.rs

@@ -179,7 +179,9 @@ pub fn parse(data: &[u8]) -> Result<Playlist> {
             }
             // PG subtitles
             for _ in 0..n_pg {
-                if let Some((entry, next)) = parse_stream_entry(item, spos, STREAM_CATEGORY_PG_SUBTITLE) {
+                if let Some((entry, next)) =
+                    parse_stream_entry(item, spos, STREAM_CATEGORY_PG_SUBTITLE)
+                {
                     streams.push(entry);
                     spos = next;
                 } else {
@@ -196,7 +198,9 @@ pub fn parse(data: &[u8]) -> Result<Playlist> {
             }
             // Secondary audio
             for _ in 0..n_sec_audio {
-                if let Some((mut entry, next)) = parse_stream_entry(item, spos, STREAM_CATEGORY_AUDIO) {
+                if let Some((mut entry, next)) =
+                    parse_stream_entry(item, spos, STREAM_CATEGORY_AUDIO)
+                {
                     entry.stream_type = 5;
                     entry.secondary = true;
                     streams.push(entry);
@@ -213,7 +217,9 @@ pub fn parse(data: &[u8]) -> Result<Playlist> {
             }
             // Secondary video (PiP)
             for _ in 0..n_sec_video {
-                if let Some((mut entry, next)) = parse_stream_entry(item, spos, STREAM_CATEGORY_VIDEO) {
+                if let Some((mut entry, next)) =
+                    parse_stream_entry(item, spos, STREAM_CATEGORY_VIDEO)
+                {
                     entry.stream_type = 6;
                     entry.secondary = true;
                     streams.push(entry);
@@ -240,7 +246,9 @@ pub fn parse(data: &[u8]) -> Result<Playlist> {
             }
             // Secondary PG (PiP subtitles) — must consume to keep spos aligned
             for _ in 0..n_pip_pg {
-                if let Some((mut entry, next)) = parse_stream_entry(item, spos, STREAM_CATEGORY_PG_SUBTITLE) {
+                if let Some((mut entry, next)) =
+                    parse_stream_entry(item, spos, STREAM_CATEGORY_PG_SUBTITLE)
+                {
                     entry.secondary = true;
                     streams.push(entry);
                     // Skip reference data: num_refs(1) + reserved(1) + refs + padding
@@ -256,7 +264,9 @@ pub fn parse(data: &[u8]) -> Result<Playlist> {
             }
             // Dolby Vision enhancement layer
             for _ in 0..n_dv {
-                if let Some((mut entry, next)) = parse_stream_entry(item, spos, STREAM_CATEGORY_VIDEO) {
+                if let Some((mut entry, next)) =
+                    parse_stream_entry(item, spos, STREAM_CATEGORY_VIDEO)
+                {
                     entry.stream_type = 7;
                     entry.secondary = true;
                     streams.push(entry);
@@ -333,6 +343,7 @@ const STREAM_CATEGORY_PG_SUBTITLE: u8 = 3;
 const STREAM_CATEGORY_IG: u8 = 4;
 
 fn parse_stream_entry(item: &[u8], pos: usize, stream_type: u8) -> Option<(StreamEntry, usize)> {
+    use crate::consts::coding_type as c;
     if pos + 2 > item.len() {
         return None;
     }
@@ -387,22 +398,27 @@ fn parse_stream_entry(item: &[u8], pos: usize, stream_type: u8) -> Option<(Strea
     let mut color_space_val = 0u8;
     let mut language = String::new();
 
+    // `stream_type` here is the STN category passed by the caller, which is
+    // only ever a primary category (VIDEO/AUDIO/PG_SUBTITLE/IG). Secondary
+    // audio/video and the DV enhancement layer are parsed through their
+    // matching primary category (identical attribute layout) and re-tagged by
+    // the caller after this returns, so there are no secondary arms here.
     match stream_type {
-        1 => {
+        STREAM_CATEGORY_VIDEO => {
             // Video: coding_type(1) + format_rate(1) + [hdr_info(1) if HEVC]
             if sa.len() >= 2 {
                 video_format = (sa[1] >> 4) & 0x0F;
                 video_rate = sa[1] & 0x0F;
             }
-            if coding_type == 0x24 && sa.len() > 2 {
+            if coding_type == c::HEVC && sa.len() > 2 {
                 dynamic_range = (sa[2] >> 4) & 0x0F;
                 color_space_val = sa[2] & 0x0F;
             }
         }
-        2 => {
+        STREAM_CATEGORY_AUDIO => {
             // Audio: coding_type(1) + format_rate(1) + language(3)
-            // Exception: PGS (0x90/0x91) in audio slot uses PG layout: coding_type(1) + language(3)
-            if coding_type == 0x90 || coding_type == 0x91 {
+            // Exception: PG/IG in an audio slot uses PG layout: coding_type(1) + language(3)
+            if coding_type == c::PG || coding_type == c::IG {
                 if sa.len() >= 4 {
                     language = String::from_utf8_lossy(&sa[1..4]).to_string();
                 }
@@ -416,35 +432,14 @@ fn parse_stream_entry(item: &[u8], pos: usize, stream_type: u8) -> Option<(Strea
                 }
             }
         }
-        3 => {
+        STREAM_CATEGORY_PG_SUBTITLE => {
             // PG: coding_type(1) + language(3).
-            // IG (type 4) is parsed only to advance spos and is then
-            // discarded by the caller, so it deliberately has no arm here.
+            // IG is parsed only to advance spos and is then discarded by the
+            // caller, so it deliberately has no arm here.
             if sa.len() >= 4 {
                 language = String::from_utf8_lossy(&sa[1..4]).to_string();
             }
         }
-        5 => {
-            // Secondary audio: same as primary audio
-            if sa.len() >= 2 {
-                audio_format = (sa[1] >> 4) & 0x0F;
-                audio_rate = sa[1] & 0x0F;
-            }
-            if sa.len() >= 5 {
-                language = String::from_utf8_lossy(&sa[2..5]).to_string();
-            }
-        }
-        6 | 7 => {
-            // Secondary video: same as primary video
-            if sa.len() >= 2 {
-                video_format = (sa[1] >> 4) & 0x0F;
-                video_rate = sa[1] & 0x0F;
-            }
-            if coding_type == 0x24 && sa.len() > 2 {
-                dynamic_range = (sa[2] >> 4) & 0x0F;
-                color_space_val = sa[2] & 0x0F;
-            }
-        }
         _ => {}
     }
 

src/mux/m2ts_mux/mod.rs

@@ -76,15 +76,18 @@ const PCR_INTERVAL_PACKETS: u64 = 40;
 /// the picture it timestamps. 200 ms in 90 kHz ticks.
 const PCR_LEAD_90KHZ: u64 = 90_000 / 5;
 
+// PMT stream-type codes. These are the same elementary-stream coding-type
+// registry as the parse side; the single source of truth is `consts::coding_type`.
+use crate::consts::coding_type;
 /// HEVC stream-type code, ISO/IEC 13818-1 Table 2-34 (2015 amendment).
-const STREAM_TYPE_HEVC: u8 = 0x24;
+const STREAM_TYPE_HEVC: u8 = coding_type::HEVC;
 /// AC-3 / E-AC-3. Not an ISO assignment — sits in the user-private
 /// 0x80-0xFF range and is the Blu-ray Disc Association / ATSC A/52
 /// convention.
-const STREAM_TYPE_AC3: u8 = 0x81;
+const STREAM_TYPE_AC3: u8 = coding_type::AC3;
 /// Dolby TrueHD. Also a private/BD-conventional value in the
 /// user-private 0x80-0xFF range, not an ISO assignment.
-const STREAM_TYPE_TRUEHD: u8 = 0x83;
+const STREAM_TYPE_TRUEHD: u8 = coding_type::TRUEHD;
 
 /// Audio codec hint for [`M2tsMux::new`] / [`M2tsMux::set_audio`]. The
 /// muxer needs to know the codec to pick the right PMT `stream_type`
@@ -420,7 +423,12 @@ impl<W: Write> M2tsMux<W> {
 
 /// Build a PES packet for a video access unit.
 fn build_video_pes(pts_90k: u64, es: &[u8]) -> Vec<u8> {
-    build_pes_packet(0xE0, pts_90k, es, /* length_in_header */ false)
+    build_pes_packet(
+        crate::consts::pes_stream_id::VIDEO,
+        pts_90k,
+        es,
+        /* length_in_header */ false,
+    )
 }
 
 /// Build a PES packet for an audio access unit.
@@ -430,7 +438,12 @@ fn build_audio_pes(pts_90k: u64, es: &[u8]) -> Vec<u8> {
     // start code. For an access unit larger than ~64 KiB (rare — e.g. a
     // large TrueHD frame) the length field falls back to the unbounded
     // (0x0000) form, which most demuxers tolerate for private_stream_1.
-    build_pes_packet(0xBD, pts_90k, es, /* length_in_header */ true)
+    build_pes_packet(
+        crate::consts::pes_stream_id::PRIVATE_STREAM_1,
+        pts_90k,
+        es,
+        /* length_in_header */ true,
+    )
 }
 
 fn build_pes_packet(stream_id: u8, pts_90k: u64, es: &[u8], length_in_header: bool) -> Vec<u8> {

src/mux/ps.rs

@@ -23,10 +23,10 @@ const SYSTEM_HEADER_ID: u8 = 0xBB;
 const PROGRAM_END_ID: u8 = 0xB9;
 
 /// Private stream 1 (AC3, DTS, LPCM, subtitles).
-const PRIVATE_STREAM_1: u8 = 0xBD;
+const PRIVATE_STREAM_1: u8 = crate::consts::pes_stream_id::PRIVATE_STREAM_1;
 /// Private stream 2 (0xBF) — DVD navigation (PCI/DSI). Carries no muxable
 /// elementary stream; expected to be dropped on every disc.
-const PRIVATE_STREAM_2: u8 = 0xBF;
+const PRIVATE_STREAM_2: u8 = crate::consts::pes_stream_id::PRIVATE_STREAM_2;
 
 /// Hard cap on the demuxer's reassembly buffer. A length-0 (unbounded) video
 /// PES is delimited by the next PS-layer boundary; if a corrupt stream declares
@@ -107,8 +107,8 @@ impl PsPacket {
     /// mis-routing the packet.
     pub fn dvd_pid(&self) -> Option<u16> {
         match self.stream_id {
-            0xE0..=0xEF => Some(DVD_VIDEO_PID),
-            0xBD => {
+            crate::consts::pes_stream_id::VIDEO..=0xEF => Some(DVD_VIDEO_PID),
+            PRIVATE_STREAM_1 => {
                 let sub = self.sub_stream_id?;
                 dvd_audio_pid(sub).or_else(|| dvd_subtitle_pid(sub))
             }
@@ -348,8 +348,8 @@ fn find_ps_boundary(data: &[u8], from: usize) -> Option<usize> {
 fn is_pes_stream_id(id: u8) -> bool {
     // Video: 0xE0-0xEF, MPEG audio: 0xC0-0xDF, private stream 1: 0xBD,
     // private stream 2: 0xBF, padding: 0xBE, ECM/EMM etc.
-    // We parse anything in the PES range.
-    matches!(id, 0xBD..=0xEF)
+    // We parse anything in the payload-bearing PES range.
+    crate::consts::pes_stream_id::PAYLOAD_RANGE.contains(&id)
 }
 
 /// Parse a single PES packet from a byte slice that starts at the start code.
@@ -365,12 +365,12 @@ fn parse_pes_packet(data: &[u8]) -> Option<PsPacket> {
     let stream_id = data[3];
 
     // Padding stream — skip entirely.
-    if stream_id == 0xBE {
+    if stream_id == crate::consts::pes_stream_id::PADDING_STREAM {
         return None;
     }
 
     // Streams without standard PES header extension.
-    if stream_id == 0xBF {
+    if stream_id == PRIVATE_STREAM_2 {
         let payload = if data.len() > 6 { &data[6..] } else { &[] };
         return Some(PsPacket {
             stream_id,

src/mux/tsmux.rs

@@ -312,11 +312,12 @@ impl<W: Write> TsMuxer<W> {
 
 /// Build a PES packet header for a BD stream.
 fn build_pes_header(pid: u16, pts_90k: u64, data_len: usize) -> Vec<u8> {
+    use crate::consts::pes_stream_id;
     // Determine stream_id from PID range
     let stream_id: u8 = if is_video_pid(pid) {
-        0xE0 // video
+        pes_stream_id::VIDEO
     } else {
-        0xBD // audio, PGS subtitle, or default (private stream 1)
+        pes_stream_id::PRIVATE_STREAM_1 // audio, PGS subtitle, or default
     };
 
     let pes_data_len = data_len + 8; // 3 header bytes + 5 PTS bytes + data
@@ -332,7 +333,7 @@ fn build_pes_header(pid: u16, pts_90k: u64, data_len: usize) -> Vec<u8> {
     // video; `write_frame` splits oversized 0xBD access units so a private
     // stream always fits a bounded u16 length here. The `> 65535` arm
     // remains a defensive fallback for video only.
-    if stream_id == 0xE0 || pes_data_len > 65535 {
+    if stream_id == pes_stream_id::VIDEO || pes_data_len > u16::MAX as usize {
         header.push(0x00);
         header.push(0x00);
     } else {