mux: HD-DVD VC-1 demux via extended stream id 0xFD
VC-1 HD-DVDs (e.g. Shaun of the Dead) carry video on MPEG-PS extended stream id 0xFD, with the real stream selector in stream_id_extension inside the PES extension. Parse that field so the video routes to a distinct track (pid 0xFD00|ext) instead of being dropped. Reframe VC-1 access units in AuAssembler with a dedicated Mode::Vc1: an AU is delimited by the next frame BDU (0x0D) once a frame has already been seen, so the sequence (0x0F) and entry-point (0x0E) headers that precede an I-frame stay attached to the frame they describe. The old single-start-code split stranded those headers on the prior AU, which the decoder reported as bits-overconsumption and hard decode failures. hddvd probe now tracks the video pid it detects and emits VC-1 on 0xFD.
This commit is contained in:
Matthew Jackson
+211
-5
@@ -27,6 +27,12 @@ const PRIVATE_STREAM_1: u8 = crate::consts::pes_stream_id::PRIVATE_STREAM_1;
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/// Private stream 2 (0xBF) — DVD navigation (PCI/DSI). Carries no muxable
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/// elementary stream; expected to be dropped on every disc.
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const PRIVATE_STREAM_2: u8 = crate::consts::pes_stream_id::PRIVATE_STREAM_2;
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/// Extended stream id (0xFD) — the H.222.0 escape whereby the real stream id is
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/// the `stream_id_extension` carried in the PES extension. HD-DVD `.evo` puts its
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/// VC-1 video (and HD audio) here (Shaun of the Dead: VC-1 on `0xFD` ext `0x55`);
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/// a transport stream never uses it. The elementary-stream bytes follow the PES
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/// header exactly like any other PES — only the routing key differs.
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const EXTENDED_STREAM_ID: u8 = 0xFD;
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/// Hard cap on the demuxer's reassembly buffer. A length-0 (unbounded) video
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/// PES is delimited by the next PS-layer boundary; if a corrupt stream declares
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@@ -73,9 +79,16 @@ pub const DVD_VIDEO_PID: u16 = 0xE0;
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/// source of truth shared with `Disc::scan_dvd_titles`
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/// (`src/disc/dvd.rs`), which sets each `AudioStream.pid` from the same
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/// function so demuxer output routes through the title's `pid_to_track`.
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///
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/// HD-DVD (`.evo` Enhanced VOB) carries Dolby Digital Plus (E-AC-3) on
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/// `private_stream_1` sub-stream ids `0xC0..=0xC7` — a range DVD never uses
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/// (DVD audio is `0x80..=0x8F` / `0xA0..=0xA7`), so admitting it here is purely
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/// additive and cannot change any DVD mapping. The PID is `0xBD00 | sub` just
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/// like the DVD audio ranges, so a mixed HD-DVD title (four DD+ tracks
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/// `0xC0..0xC3`) routes each track to its own distinct PID.
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pub fn dvd_audio_pid(sub_stream_id: u8) -> Option<u16> {
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match sub_stream_id {
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0x80..=0x8F | 0xA0..=0xA7 => Some(0xBD00 | sub_stream_id as u16),
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0x80..=0x8F | 0xA0..=0xA7 | 0xC0..=0xC7 => Some(0xBD00 | sub_stream_id as u16),
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_ => None,
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}
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}
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@@ -90,6 +103,17 @@ pub fn dvd_subtitle_pid(sub_stream_id: u8) -> Option<u16> {
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}
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}
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/// Canonical PID for an HD-DVD extended-stream-id (`0xFD`) stream, keyed by its
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/// `stream_id_extension`: `0xFD00 | ext`. Disjoint from the DVD video (`0xE0`) and
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/// `private_stream_1` (`0xBD00..`) PID spaces, so several elementary streams
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/// multiplexed on `0xFD` (VC-1 video, MLP/TrueHD audio) never collide. The
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/// scanner's head probe and `PsPacket::dvd_pid` derive the same PID from the same
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/// `stream_id_extension`, so demux output routes through the title's
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/// `pid_to_track`.
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pub fn hddvd_extended_pid(stream_id_extension: u8) -> u16 {
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0xFD00 | stream_id_extension as u16
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}
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impl PsPacket {
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/// Map this packet to the canonical DVD PID assigned by
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/// `Disc::scan_dvd_titles` (`src/disc/dvd.rs`), so demux output can
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@@ -112,6 +136,12 @@ impl PsPacket {
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let sub = self.sub_stream_id?;
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dvd_audio_pid(sub).or_else(|| dvd_subtitle_pid(sub))
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}
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// HD-DVD extended-stream-id (0xFD): route by the stream_id_extension
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// (carried in `sub_stream_id`) to a distinct `0xFD00 | ext` PID, so a
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// disc that puts several elementary streams on 0xFD keeps them apart.
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// The codec (VC-1 etc.) is decided by the scanner's head probe, not
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// here — this only assigns a stable routing key.
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EXTENDED_STREAM_ID => self.sub_stream_id.map(hddvd_extended_pid),
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_ => None,
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}
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}
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@@ -347,9 +377,74 @@ fn find_ps_boundary(data: &[u8], from: usize) -> Option<usize> {
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/// Check whether a start code byte is a valid PES stream ID that carries payload.
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fn is_pes_stream_id(id: u8) -> bool {
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// Video: 0xE0-0xEF, MPEG audio: 0xC0-0xDF, private stream 1: 0xBD,
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// private stream 2: 0xBF, padding: 0xBE, ECM/EMM etc.
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// We parse anything in the payload-bearing PES range.
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crate::consts::pes_stream_id::PAYLOAD_RANGE.contains(&id)
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// private stream 2: 0xBF, padding: 0xBE, ECM/EMM etc. — plus the HD-DVD
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// extended-stream-id (0xFD), which carries VC-1 video / HD audio.
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crate::consts::pes_stream_id::PAYLOAD_RANGE.contains(&id) || id == EXTENDED_STREAM_ID
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}
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/// For an extended-stream-id (`0xFD`) PES, walk the optional PES-header fields to
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/// the PES extension and read the 7-bit `stream_id_extension` — the real stream
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/// id. `data` starts at the PES start code; the optional fields live in
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/// `data[9..header_end]` (all bounds-checked against `header_end`). Returns `None`
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/// if the extension is absent or malformed.
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fn parse_stream_id_extension(data: &[u8], flags2: u8, header_end: usize) -> Option<u8> {
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let get = |p: usize| -> Option<u8> {
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if p < header_end {
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data.get(p).copied()
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} else {
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None
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}
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};
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let mut pos = 9usize;
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let pts_dts = (flags2 >> 6) & 0x03;
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if pts_dts & 0x02 != 0 {
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pos += 5; // PTS
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}
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if pts_dts == 0x03 {
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pos += 5; // DTS
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}
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if flags2 & 0x20 != 0 {
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pos += 6; // ESCR
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}
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if flags2 & 0x10 != 0 {
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pos += 3; // ES_rate
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}
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if flags2 & 0x08 != 0 {
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pos += 1; // DSM_trick_mode
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}
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if flags2 & 0x04 != 0 {
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pos += 1; // additional_copy_info
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}
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if flags2 & 0x02 != 0 {
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pos += 2; // PES_CRC
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}
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if flags2 & 0x01 == 0 {
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return None; // no PES_extension
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}
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let ext_flags = get(pos)?;
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pos += 1;
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if ext_flags & 0x80 != 0 {
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pos += 16; // PES_private_data
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}
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if ext_flags & 0x40 != 0 {
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// pack_header_field: 1-byte length + that many bytes.
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pos += 1 + get(pos)? as usize;
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}
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if ext_flags & 0x20 != 0 {
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pos += 2; // program_packet_sequence_counter
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}
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if ext_flags & 0x10 != 0 {
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pos += 2; // P-STD_buffer
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}
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if ext_flags & 0x01 == 0 {
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return None; // no PES_extension_flag_2
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}
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// PES_extension_field_length (7 bits, marker in the top bit), then the
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// stream_id_extension byte: present when its top bit (the extension flag) is 0.
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let _field_len = get(pos)? & 0x7F;
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pos += 1;
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let b = get(pos)?;
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(b & 0x80 == 0).then_some(b & 0x7F)
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}
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/// Parse a single PES packet from a byte slice that starts at the start code.
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@@ -416,10 +511,30 @@ fn parse_pes_packet(data: &[u8]) -> Option<PsPacket> {
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// For private stream 1, the first payload byte is the sub-stream ID,
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// followed by a sub-header whose length depends on the sub-stream type.
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let (sub_stream_id, es_data) = if stream_id == PRIVATE_STREAM_1 && !payload.is_empty() {
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let (sub_stream_id, es_data) = if stream_id == EXTENDED_STREAM_ID {
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// HD-DVD extended-stream-id: the real stream id lives in the
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// stream_id_extension inside the PES extension. There is no leading
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// sub-header byte on the payload (unlike private_stream_1), so the ES
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// is the payload verbatim.
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(
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parse_stream_id_extension(data, data[7], header_end),
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payload.to_vec(),
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)
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} else if stream_id == PRIVATE_STREAM_1 && !payload.is_empty() {
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let sub_id = payload[0];
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let skip = match sub_id {
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0x80..=0x8F => 4, // AC3/DTS: sub_id + frame_count + access_unit_ptr(2)
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// HD-DVD Dolby Digital Plus (E-AC-3): the sub-header is the same
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// 4-byte shape as DVD AC-3 — sub_id + number_of_frames(1) +
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// first_access_unit_pointer(2). Verified empirically on ANCHORMAN
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// EVO: across every 0xC0..=0xC7 packet the 0x0B77 E-AC-3 syncword
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// sits `first_access_unit_pointer` bytes past this 4-byte header
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// (the leading bytes are the tail of the previous frame). Stripping
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// exactly these 4 bytes on EVERY packet yields a clean, continuous
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// E-AC-3 elementary stream that the ac3 parser reassembles across
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// PES boundaries; a shorter skip would splice the sub-header bytes
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// into a straddling frame and corrupt it.
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0xC0..=0xC7 => 4,
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0xA0..=0xA7 => 7, // LPCM: sub_id + frames + ptr(2) + emphasis + quant_freq + channels
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_ => 1,
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};
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@@ -836,6 +951,52 @@ mod tests {
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}
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}
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#[test]
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fn parse_extended_stream_id_extracts_stream_id_extension() {
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// SHAUN's VC-1 video PES: stream_id 0xFD, flags2=0x01 (PES_extension
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// only), header_data_length=3, optional bytes 0x0F/... — build the
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// minimal well-formed variant: ext_flags=0x01 (PES_extension_flag_2),
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// field_len=0x81, stream_id_extension=0x55. Payload is the ES.
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let mut pkt = vec![0x00, 0x00, 0x01, EXTENDED_STREAM_ID];
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let opt = [0x01u8, 0x81, 0x55];
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let es = [0xDEu8, 0xAD, 0xBE, 0xEF];
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let len = (3 + opt.len() + es.len()) as u16;
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pkt.extend_from_slice(&len.to_be_bytes());
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pkt.extend_from_slice(&[0x80, 0x01, opt.len() as u8]);
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pkt.extend_from_slice(&opt);
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pkt.extend_from_slice(&es);
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let parsed = parse_pes_packet(&pkt).expect("parses");
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assert_eq!(parsed.stream_id, EXTENDED_STREAM_ID);
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assert_eq!(
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parsed.sub_stream_id,
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Some(0x55),
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"stream_id_extension extracted from PES extension"
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);
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// ES is the payload verbatim — no leading sub-header byte stripped.
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assert_eq!(parsed.data, es);
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// Routes to the extended-stream-id PID space.
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assert_eq!(parsed.dvd_pid(), Some(hddvd_extended_pid(0x55)));
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assert_eq!(parsed.dvd_pid(), Some(0xFD55));
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}
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#[test]
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fn parse_extended_stream_id_without_extension_yields_no_sub_id() {
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// A 0xFD PES that declares no PES_extension (flags2=0x00) can't carry a
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// stream_id_extension → sub_stream_id None, and dvd_pid falls through.
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let mut pkt = vec![0x00, 0x00, 0x01, EXTENDED_STREAM_ID];
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let es = [0x11u8, 0x22];
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let len = (3 + es.len()) as u16;
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pkt.extend_from_slice(&len.to_be_bytes());
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pkt.extend_from_slice(&[0x80, 0x00, 0x00]);
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pkt.extend_from_slice(&es);
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let parsed = parse_pes_packet(&pkt).expect("parses");
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assert_eq!(parsed.sub_stream_id, None);
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assert_eq!(parsed.dvd_pid(), None);
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assert_eq!(parsed.data, es);
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}
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#[test]
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fn dvd_pid_matches_scanner_assignment() {
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// Video → 0xE0 (matches dvd.rs VideoStream pid).
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@@ -1175,6 +1336,51 @@ mod tests {
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assert_eq!(dvd_audio_pid(0xA8), None);
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}
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#[test]
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fn hddvd_ddplus_substream_maps_to_bd_pid() {
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// HD-DVD Dolby Digital Plus sub-ids 0xC0..=0xC7 map to 0xBD00|sub,
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// distinct per track and disjoint from the DVD audio space. A DVD never
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// emits these, so the range is purely additive.
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assert_eq!(dvd_audio_pid(0xC0), Some(0xBDC0));
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assert_eq!(dvd_audio_pid(0xC3), Some(0xBDC3));
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assert_eq!(dvd_audio_pid(0xC7), Some(0xBDC7));
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// Just outside the range.
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assert_eq!(dvd_audio_pid(0xBF), None);
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assert_eq!(dvd_audio_pid(0xC8), None);
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// Four DD+ tracks (ANCHORMAN) get four distinct PIDs.
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let pids: Vec<u16> = (0xC0u8..=0xC3).map(|s| dvd_audio_pid(s).unwrap()).collect();
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assert_eq!(pids, vec![0xBDC0, 0xBDC1, 0xBDC2, 0xBDC3]);
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// And route through dvd_pid on a private_stream_1 packet.
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assert_eq!(mk(0xBD, Some(0xC0)).dvd_pid(), Some(0xBDC0));
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assert_eq!(mk(0xBD, Some(0xC3)).dvd_pid(), Some(0xBDC3));
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}
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#[test]
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fn hddvd_ddplus_pes_strips_4byte_subheader_to_syncword() {
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// A private_stream_1 PES carrying DD+ (sub-id 0xC0) has a 4-byte
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// sub-header (sub_id + num_frames(1) + access_unit_ptr(2)); the demuxer
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// must strip exactly those 4 bytes so es_data begins at the E-AC-3
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// payload — here the 0x0B77 syncword sits right after the sub-header.
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let mut demuxer = PsDemuxer::new();
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let mut data = vec![
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0x00, 0x00, 0x01, 0xBD, // private stream 1
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0x00, 0x0B, // PES_packet_length = 11 (flags2 + hdl1 + 8 payload)
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0x80, 0x00, 0x00, // no PTS, header_data_len = 0
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0xC0, // sub-stream id: DD+ track 0
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0x01, 0x00, 0x00, // num_frames(1) + access_unit_ptr(2)
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0x0B, 0x77, 0xDE, 0xAD, // E-AC-3 syncword + payload
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];
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data.extend_from_slice(&[0x00, 0x00, 0x01, 0xB9]);
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let p = demuxer.feed(&data);
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assert_eq!(p.len(), 1);
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assert_eq!(p[0].sub_stream_id, Some(0xC0));
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assert_eq!(
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p[0].data,
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vec![0x0B, 0x77, 0xDE, 0xAD],
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"4-byte DD+ sub-header stripped; es_data starts at the syncword"
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);
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}
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#[test]
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fn dvd_subtitle_pid_range_boundaries() {
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// VobSub subtitle sub-ids 0x20..=0x3F map to the identity PID.
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