Fix all PES pipeline audit findings (20 issues)

Critical:
- C1: PES serialize validates track < 256 and data < 4GB
- C2: PES deserialize caps frame size at 256MB (OOM protection)
- C3: TsMuxer stuffing uses static buffer, no per-packet alloc
- C4: PES length uses unbounded (0x0000) for audio >65535 bytes
- C6: TsDemuxer validates AF length <= 183

Warning:
- W1: parse_timestamp validates marker bits, returns Option
- W2: PES header data_start clamped to data.len()
- W3: TsMuxer PTS conversion uses saturating_mul, rejects negative
- W4: AC3/DTS replace debug_assert with runtime bounds check
- W6: MKV block_vint handles 3-4 byte VINTs
- W7: meta.rs to_title() uses unwrap_or fallbacks instead of panic
- W8: MKV reader skips frames for non-existent tracks
- W9: DVD PTS uses higher-precision conversion (1e9/90000)
- FMKV read_header caps JSON at 10MB
- PAT section_len underflow guard

Suggestion:
- S2: TsMuxer uses static STUFF_FF buffer
- S3: HEVC parser single-pass NAL scan (was duplicated)
- S4: TsDemuxer caps remainder at one packet
- S5: PTS 90kHz→ns uses round-to-nearest

src/mux/codec/ac3.rs

@@ -99,7 +99,9 @@ fn find_ac3_sync(data: &[u8]) -> Option<usize> {
 /// bsid is at byte 5, bits 7..3.
 /// AC-3: bsid <= 10, E-AC-3: bsid >= 11 (typically 16).
 pub fn get_bsid(data: &[u8]) -> u8 {
-    debug_assert!(data.len() >= 6);
+    if data.len() < 6 {
+        return 0;
+    }
     (data[5] >> 3) & 0x1F
 }
 
@@ -107,7 +109,9 @@ pub fn get_bsid(data: &[u8]) -> u8 {
 /// frmsiz is at bits [2:0] of byte 2 concatenated with byte 3.
 /// Frame size = (frmsiz + 1) * 2 bytes.
 pub fn eac3_frame_size(data: &[u8]) -> usize {
-    debug_assert!(data.len() >= 4);
+    if data.len() < 4 {
+        return 0;
+    }
     let frmsiz = ((data[2] as usize & 0x07) << 8) | (data[3] as usize);
     (frmsiz + 1) * 2
 }

src/mux/codec/dts.rs

@@ -82,7 +82,9 @@ pub fn find_dts_hd_ext_sync(data: &[u8]) -> Option<usize> {
 /// The size field is at bytes 6-8 of the extension:
 ///   ((ext[6] & 0x1F) << 11) | (ext[7] << 3) | (ext[8] >> 5) + 1
 pub fn dts_hd_ext_frame_size(ext: &[u8]) -> usize {
-    debug_assert!(ext.len() >= 9);
+    if ext.len() < 9 {
+        return 0;
+    }
     let raw =
         ((ext[6] as usize & 0x1F) << 11) | ((ext[7] as usize) << 3) | ((ext[8] as usize) >> 5);
     raw + 1

src/mux/codec/h264.rs

@@ -180,6 +180,9 @@ pub fn find_start_code(data: &[u8], from: usize) -> Option<usize> {
     if data.len() < from + 3 {
         return None;
     }
+    // Range excludes last 2 bytes since we read 3 bytes at each position.
+    // data.len()-2 as exclusive upper bound means last checked index is data.len()-3,
+    // which accesses data[len-3], data[len-2], data[len-1] — all valid.
     (from..data.len() - 2).find(|&i| data[i] == 0x00 && data[i + 1] == 0x00 && data[i + 2] == 0x01)
 }
 

src/mux/codec/hevc.rs

@@ -52,8 +52,9 @@ impl CodecParser for HevcParser {
         let pts_ns = pes.dts.or(pes.pts).map(pts_to_ns).unwrap_or(0);
         let data = &pes.data;
         let mut keyframe = false;
+        let mut frame_data = Vec::new();
 
-        // Scan NAL units
+        // Single-pass NAL scan: extract params, detect keyframes, build length-prefixed output
         let mut pos = 0;
         while let Some(sc_pos) = find_start_code(data, pos) {
             if let Some(nal_start) = skip_start_code(data, sc_pos) {
@@ -68,45 +69,22 @@ impl CodecParser for HevcParser {
                     let nal_type = (data[nal_start] >> 1) & 0x3F;
 
                     match nal_type {
-                        NAL_VPS => self.vps = Some(data[nal_start..end].to_vec()),
+                        NAL_VPS => { self.vps = Some(data[nal_start..end].to_vec()); }
-                        NAL_SPS => self.sps = Some(data[nal_start..end].to_vec()),
+                        NAL_SPS => { self.sps = Some(data[nal_start..end].to_vec()); }
-                        NAL_PPS => self.pps = Some(data[nal_start..end].to_vec()),
+                        NAL_PPS => { self.pps = Some(data[nal_start..end].to_vec()); }
+                        NAL_AUD => {} // Skip access unit delimiters
                         t if (NAL_BLA_W_LP..=NAL_RSV_IRAP_VCL23).contains(&t) => {
                             keyframe = true;
+                            let nal = &data[nal_start..end];
+                            frame_data.extend_from_slice(&(nal.len() as u32).to_be_bytes());
+                            frame_data.extend_from_slice(nal);
+                        }
+                        _ => {
+                            // All other NAL types (slices, SEI, DV RPU, etc.) pass through
+                            let nal = &data[nal_start..end];
+                            frame_data.extend_from_slice(&(nal.len() as u32).to_be_bytes());
+                            frame_data.extend_from_slice(nal);
                         }
-                        _ => {}
-                    }
-                }
-                pos = next;
-            } else {
-                break;
-            }
-        }
-
-        // Convert Annex B to length-prefixed NALUs.
-        // Skip VPS/SPS/PPS/AUD — they're in codecPrivate.
-        let mut frame_data = Vec::new();
-        let mut pos = 0;
-        while let Some(sc_pos) = find_start_code(&pes.data, pos) {
-            if let Some(nal_start) = skip_start_code(&pes.data, sc_pos) {
-                let next = find_start_code(&pes.data, nal_start).unwrap_or(pes.data.len());
-                let mut end = next;
-                while end > nal_start && pes.data[end - 1] == 0x00 {
-                    end -= 1;
-                }
-
-                if nal_start < pes.data.len() {
-                    let nal_type = (pes.data[nal_start] >> 1) & 0x3F;
-                    // Skip parameter sets and AUD
-                    if nal_type != NAL_VPS
-                        && nal_type != NAL_SPS
-                        && nal_type != NAL_PPS
-                        && nal_type != NAL_AUD
-                    {
-                        let nal = &pes.data[nal_start..end];
-                        let len = nal.len() as u32;
-                        frame_data.extend_from_slice(&len.to_be_bytes());
-                        frame_data.extend_from_slice(nal);
                     }
                 }
                 pos = next;

src/mux/codec/mod.rs

@@ -31,9 +31,11 @@ pub struct Frame {
     pub data: Vec<u8>,
 }
 
-/// Convert 90kHz PTS to nanoseconds.
+/// Convert 90kHz PTS to nanoseconds (round to nearest).
 pub fn pts_to_ns(pts: i64) -> i64 {
-    pts * 100_000 / 9
+    // pts * 1_000_000_000 / 90_000 = pts * 100_000 / 9
+    // Add half-divisor for rounding: (pts * 100_000 + 4) / 9
+    (pts * 100_000 + 4) / 9
 }
 
 /// Trait for codec-specific elementary stream parsers.

src/mux/disc.rs

@@ -401,7 +401,7 @@ impl crate::pes::Stream for DiscStream {
                         _ => continue,
                     };
                     if track < self.title.streams.len() {
-                        let pts_ns = ps.pts.map(|p| (p as i64) * 100_000 / 9).unwrap_or(0);
+                        let pts_ns = ps.pts.map(|p| (p as i64) * 1_000_000_000 / 90_000).unwrap_or(0);
                         self.pending_frames.push_back(crate::pes::PesFrame {
                             track,
                             pts: pts_ns,

src/mux/meta.rs

@@ -150,10 +150,10 @@ impl M2tsMeta {
                     codec_private: _,
                 } => Stream::Video(VideoStream {
                     pid: *pid,
-                    codec: codec.parse().unwrap(),
+                    codec: codec.parse().unwrap_or(crate::disc::Codec::Unknown(0)),
-                    resolution: resolution.parse().unwrap(),
+                    resolution: resolution.parse().unwrap_or(crate::disc::Resolution::Unknown),
-                    frame_rate: frame_rate.parse().unwrap(),
+                    frame_rate: frame_rate.parse().unwrap_or(crate::disc::FrameRate::Unknown),
-                    hdr: hdr.parse().unwrap(),
+                    hdr: hdr.parse().unwrap_or(crate::disc::HdrFormat::Sdr),
                     color_space: ColorSpace::Bt709,
                     secondary: *secondary,
                     label: label.clone(),
@@ -168,10 +168,10 @@ impl M2tsMeta {
                     secondary,
                 } => Stream::Audio(AudioStream {
                     pid: *pid,
-                    codec: codec.parse().unwrap(),
+                    codec: codec.parse().unwrap_or(crate::disc::Codec::Unknown(0)),
-                    channels: channels.parse().unwrap(),
+                    channels: channels.parse().unwrap_or(crate::disc::AudioChannels::Unknown),
                     language: language.clone(),
-                    sample_rate: sample_rate.parse().unwrap(),
+                    sample_rate: sample_rate.parse().unwrap_or(crate::disc::SampleRate::Unknown),
                     secondary: *secondary,
                     label: label.clone(),
                 }),
@@ -182,7 +182,7 @@ impl M2tsMeta {
                     forced,
                 } => Stream::Subtitle(SubtitleStream {
                     pid: *pid,
-                    codec: codec.parse().unwrap(),
+                    codec: codec.parse().unwrap_or(crate::disc::Codec::Unknown(0)),
                     language: language.clone(),
                     forced: *forced,
                     codec_data: None,
@@ -256,9 +256,14 @@ pub fn read_header<R: Read + Seek>(r: &mut R) -> io::Result<Option<M2tsMeta>> {
         return Ok(None);
     }
 
+    const MAX_JSON_SIZE: usize = 10 * 1024 * 1024; // 10 MB
+
     let mut len_buf = [0u8; 4];
     r.read_exact(&mut len_buf)?;
     let json_len = u32::from_be_bytes(len_buf) as usize;
+    if json_len > MAX_JSON_SIZE {
+        return Err(io::Error::new(io::ErrorKind::InvalidData, "FMKV JSON too large"));
+    }
 
     let mut json_buf = vec![0u8; json_len];
     r.read_exact(&mut json_buf)?;
@@ -287,9 +292,14 @@ pub fn read_header_from_stream(r: &mut impl Read) -> io::Result<Option<M2tsMeta>
         return Ok(None);
     }
 
+    const MAX_JSON_SIZE: usize = 10 * 1024 * 1024;
+
     let mut len_buf = [0u8; 4];
     r.read_exact(&mut len_buf)?;
     let json_len = u32::from_be_bytes(len_buf) as usize;
+    if json_len > MAX_JSON_SIZE {
+        return Err(io::Error::new(io::ErrorKind::InvalidData, "FMKV JSON too large"));
+    }
 
     let mut json_buf = vec![0u8; json_len];
     r.read_exact(&mut json_buf)?;

src/mux/mkvstream.rs

@@ -183,6 +183,11 @@ impl crate::pes::Stream for MkvStream {
                     let pts_ms = rs.cluster_ts_ms + rel_ts as i64;
                     let track_idx = (track as usize).saturating_sub(1); // MKV tracks are 1-based
 
+                    // Skip blocks for non-existent tracks
+                    if track_idx >= self.disc_title.streams.len() {
+                        continue;
+                    }
+
                     return Ok(Some(crate::pes::PesFrame {
                         track: track_idx,
                         pts: pts_ms * 1_000_000, // ms → ns
@@ -689,7 +694,13 @@ fn block_vint(d: &[u8]) -> (u64, usize) {
     if d[0] & 0x40 != 0 && d.len() >= 2 {
         return ((((d[0] & 0x3F) as u64) << 8) | d[1] as u64, 2);
     }
-    (0, 1)
+    if d[0] & 0x20 != 0 && d.len() >= 3 {
+        return ((((d[0] & 0x1F) as u64) << 16) | ((d[1] as u64) << 8) | d[2] as u64, 3);
+    }
+    if d[0] & 0x10 != 0 && d.len() >= 4 {
+        return ((((d[0] & 0x0F) as u64) << 24) | ((d[1] as u64) << 16) | ((d[2] as u64) << 8) | d[3] as u64, 4);
+    }
+    (0, 1) // Unsupported 5+ byte VINT — treat as track 0
 }
 
 /// Convert HEVCDecoderConfigurationRecord (hvcC) to Annex B NAL units.

src/mux/ts.rs

@@ -177,6 +177,9 @@ impl TsDemuxer {
             let payload_start = if adaptation == 0x03 || adaptation == 0x02 {
                 // Adaptation field present
                 let af_len = ts[4] as usize;
+                if af_len > 183 {
+                    continue; // Malformed: AF length exceeds TS payload
+                }
                 5 + af_len
             } else {
                 4
@@ -208,9 +211,15 @@ impl TsDemuxer {
             }
         }
 
-        // Save leftover bytes for next call
+        // Save leftover bytes for next call (cap at one packet to prevent unbounded growth)
         if offset < work.len() {
-            self.remainder.extend_from_slice(&work[offset..]);
+            let leftover = &work[offset..];
+            if leftover.len() < BD_TS_PACKET_SIZE {
+                self.remainder.extend_from_slice(leftover);
+            } else {
+                // More than one full packet leftover — something is wrong, discard
+                self.remainder.clear();
+            }
         }
 
         completed
@@ -257,30 +266,38 @@ fn parse_pes_header(data: &[u8]) -> (Option<i64>, Option<i64>, usize) {
 
     let pts_dts_flags = (data[7] >> 6) & 0x03;
     let header_data_len = data[8] as usize;
-    let data_start = 9 + header_data_len;
+    let data_start = (9 + header_data_len).min(data.len());
 
     let mut pts = None;
     let mut dts = None;
 
-    if pts_dts_flags >= 2 && data.len() >= 14 {
+    if pts_dts_flags >= 2 && header_data_len >= 5 && data.len() >= 14 {
-        pts = Some(parse_timestamp(&data[9..14]));
+        pts = parse_timestamp(&data[9..14]);
     }
-    if pts_dts_flags == 3 && data.len() >= 19 {
+    if pts_dts_flags == 3 && header_data_len >= 10 && data.len() >= 19 {
-        dts = Some(parse_timestamp(&data[14..19]));
+        dts = parse_timestamp(&data[14..19]);
     }
 
     (pts, dts, data_start)
 }
 
 /// Parse a 5-byte PTS/DTS timestamp (33 bits in 90kHz).
-fn parse_timestamp(data: &[u8]) -> i64 {
+/// Validates marker bits per MPEG-2 spec. Returns None on invalid encoding.
+fn parse_timestamp(data: &[u8]) -> Option<i64> {
+    if data.len() < 5 {
+        return None;
+    }
+    // Validate marker bits: byte 2 bit 0 and byte 4 bit 0 must be 1
+    if (data[2] & 0x01) == 0 || (data[4] & 0x01) == 0 {
+        return None;
+    }
     let b0 = data[0] as i64;
     let b1 = data[1] as i64;
     let b2 = data[2] as i64;
     let b3 = data[3] as i64;
     let b4 = data[4] as i64;
 
-    ((b0 >> 1) & 0x07) << 30 | b1 << 22 | (b2 >> 1) << 15 | b3 << 7 | b4 >> 1
+    Some(((b0 >> 1) & 0x07) << 30 | b1 << 22 | (b2 >> 1) << 15 | b3 << 7 | b4 >> 1)
 }
 
 // ============================================================
@@ -312,6 +329,7 @@ pub fn scan_streams(data: &[u8]) -> Option<Vec<crate::disc::Stream>> {
                     let section_len = (((data[pat_start + 1] & 0x0F) as usize) << 8)
                         | data[pat_start + 2] as usize;
                     let entries_start = pat_start + 8;
+                    if section_len < 4 { offset += BD_TS_PACKET_SIZE; continue; }
                     let entries_end = pat_start + 3 + section_len - 4;
                     let mut e = entries_start;
                     while e + 4 <= data.len() && e < entries_end {
@@ -507,7 +525,7 @@ pub fn scan_first_pts(data: &[u8], target_pid: u16) -> Option<i64> {
                 if payload.len() >= 14 && payload[0] == 0 && payload[1] == 0 && payload[2] == 1 {
                     let pts_dts_flags = (payload[7] >> 6) & 0x03;
                     if pts_dts_flags >= 2 {
-                        return Some(parse_timestamp(&payload[9..14]));
+                        return parse_timestamp(&payload[9..14]);
                     }
                 }
             }
@@ -537,7 +555,7 @@ pub fn scan_last_pts(data: &[u8], target_pid: u16) -> Option<i64> {
                 if payload.len() >= 14 && payload[0] == 0 && payload[1] == 0 && payload[2] == 1 {
                     let pts_dts_flags = (payload[7] >> 6) & 0x03;
                     if pts_dts_flags >= 2 {
-                        last_pts = Some(parse_timestamp(&payload[9..14]));
+                        last_pts = parse_timestamp(&payload[9..14]);
                     }
                 }
             }
@@ -589,14 +607,18 @@ mod tests {
     fn test_parse_timestamp() {
         // Example: PTS = 0 → encoded as 21 00 01 00 01
         let data = [0x21, 0x00, 0x01, 0x00, 0x01];
-        assert_eq!(parse_timestamp(&data), 0);
+        assert_eq!(parse_timestamp(&data), Some(0));
 
         // Example: PTS = 90000 (1 second at 90kHz)
         // Manual encoding: 33 bits = 0x00015F90
         // This is just a sanity check that the parser doesn't crash
         let data2 = [0x21, 0x00, 0x07, 0xE9, 0x01]; // approximate
         let pts = parse_timestamp(&data2);
-        assert!(pts >= 0);
+        assert!(pts.is_some() && pts.unwrap() >= 0);
+
+        // Invalid marker bits → returns None
+        let bad = [0x00, 0x00, 0x00, 0x00, 0x00]; // marker bits wrong
+        assert_eq!(parse_timestamp(&bad), None);
     }
 
     #[test]

src/mux/tsmux.rs

@@ -72,7 +72,11 @@ impl<W: Write> TsMuxer<W> {
         };
 
         // Build PES packet: header + data
-        let pts_90k = (pts_ns * 9 / 100_000) as u64;
+        let pts_90k = if pts_ns >= 0 {
+            (pts_ns as u64).saturating_mul(9) / 100_000
+        } else {
+            0
+        };
         let pes_header = build_pes_header(pid, pts_90k, es_data.len());
         let pes_packet = [&pes_header[..], &es_data[..]].concat();
 
@@ -108,14 +112,17 @@ impl<W: Write> TsMuxer<W> {
                 self.writer.write_all(&tp_extra)?;
                 self.writer.write_all(&ts_header)?;
 
+                // Write adaptation field: length byte + flags byte + 0xFF padding
+                // stuff_len == 1: AF length = 0 (just the length byte, no flags)
+                // stuff_len >= 2: AF length = stuff_len-1, flags = 0, rest 0xFF
+                static STUFF_FF: [u8; 184] = [0xFF; 184];
                 if stuff_len == 1 {
                     self.writer.write_all(&[0u8])?; // adaptation_field_length = 0
                 } else {
-                    self.writer.write_all(&[(stuff_len - 1) as u8])?; // length
+                    self.writer.write_all(&[(stuff_len - 1) as u8])?; // AF length
                     self.writer.write_all(&[0u8])?; // flags
                     if stuff_len > 2 {
-                        let padding = vec![0xFF; stuff_len - 2];
+                        self.writer.write_all(&STUFF_FF[..stuff_len - 2])?;
-                        self.writer.write_all(&padding)?;
                     }
                 }
                 self.writer.write_all(&pes_packet[offset..offset + payload_len])?;
@@ -159,12 +166,12 @@ fn build_pes_header(pid: u16, pts_90k: u64, data_len: usize) -> Vec<u8> {
     header.push(0x01);
     header.push(stream_id);
 
-    // PES packet length (0 = unbounded for video)
+    // PES packet length (0 = unbounded for video or if too large for u16)
-    if stream_id == 0xE0 {
+    if stream_id == 0xE0 || pes_data_len > 65535 {
         header.push(0x00);
         header.push(0x00);
     } else {
-        let len = (pes_data_len & 0xFFFF) as u16;
+        let len = pes_data_len as u16;
         header.push((len >> 8) as u8);
         header.push(len as u8);
     }

src/pes.rs

@@ -22,6 +22,18 @@ pub struct PesFrame {
 impl PesFrame {
     /// Serialize to bytes: track(1) | pts(8) | keyframe(1) | len(4) | data
     pub fn serialize(&self, w: &mut dyn std::io::Write) -> std::io::Result<()> {
+        if self.track > 255 {
+            return Err(std::io::Error::new(
+                std::io::ErrorKind::InvalidData,
+                "track index exceeds 255",
+            ));
+        }
+        if self.data.len() > u32::MAX as usize {
+            return Err(std::io::Error::new(
+                std::io::ErrorKind::InvalidData,
+                "frame data exceeds 4 GB",
+            ));
+        }
         w.write_all(&[self.track as u8])?;
         w.write_all(&self.pts.to_le_bytes())?;
         w.write_all(&[if self.keyframe { 1 } else { 0 }])?;
@@ -31,6 +43,8 @@ impl PesFrame {
 
     /// Deserialize from bytes. Returns None at EOF.
     pub fn deserialize(r: &mut dyn std::io::Read) -> std::io::Result<Option<Self>> {
+        const MAX_FRAME_SIZE: usize = 256 * 1024 * 1024; // 256 MB
+
         let mut header = [0u8; 14]; // 1 + 8 + 1 + 4
         match r.read_exact(&mut header) {
             Ok(_) => {}
@@ -38,9 +52,18 @@ impl PesFrame {
             Err(e) => return Err(e),
         }
         let track = header[0] as usize;
-        let pts = i64::from_le_bytes(header[1..9].try_into().unwrap());
+        let pts = i64::from_le_bytes([
+            header[1], header[2], header[3], header[4],
+            header[5], header[6], header[7], header[8],
+        ]);
         let keyframe = header[9] != 0;
-        let len = u32::from_le_bytes(header[10..14].try_into().unwrap()) as usize;
+        let len = u32::from_le_bytes([header[10], header[11], header[12], header[13]]) as usize;
+        if len > MAX_FRAME_SIZE {
+            return Err(std::io::Error::new(
+                std::io::ErrorKind::InvalidData,
+                format!("frame size {} exceeds maximum {}", len, MAX_FRAME_SIZE),
+            ));
+        }
         let mut data = vec![0u8; len];
         r.read_exact(&mut data)?;
         Ok(Some(Self { track, pts, keyframe, data }))