v0.25.2: DTS-HD codec ID + PGS BlockDuration
- MkvTrack::audio emits A_DTS/MA, A_DTS/HR, A_DTS per the DTS family instead of mislabelling everything as A_DTS. Plex transcoder and strict hardware decoders reject DTS-HD MA payload under a plain A_DTS track. - PgsParser is now stateful: pairs display PCS with the following empty PCS to compute a duration. Frame::duration_ns + PesFrame::duration_ns carry it through; MkvMuxer::write_frame gains a final Option<u64> parameter that emits BlockGroup + BlockDuration when set. Fixes subtitle bitmaps lingering past their intended end-time.
This commit is contained in:
MattJackson
+132
-29
@@ -1,12 +1,32 @@
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//! HDMV PGS (Presentation Graphics Stream) subtitle parser.
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//!
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//! PGS segments: PCS, WDS, PDS, ODS, END.
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//! Each PES packet contains one or more segments.
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//! All segments are keyframes (no inter-segment dependencies).
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//! PGS segments: PCS, WDS, PDS, ODS, END. Each PES packet starts with
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//! one of those (segment_type byte at offset 0).
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//!
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//! Subtitle display lifecycle (BD spec):
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//! - A "display" PCS (number_of_composition_objects > 0) starts a
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//! visible subtitle. Its WDS/PDS/ODS follow.
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//! - A later "empty" PCS (number_of_composition_objects == 0) clears
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//! the screen.
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//!
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//! For Matroska output we collapse that pair into one block with
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//! `BlockDuration` set to (clear_pts - display_pts). Without a
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//! duration, hardware players linger on the last bitmap until the
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//! next subtitle replaces it — which can be many seconds, and on a
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//! disc where the final subtitle has no follower, until end of file.
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use super::{CodecParser, Frame, PesPacket, pts_to_ns};
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pub struct PgsParser;
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const SEGMENT_PCS: u8 = 0x16;
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// Offset within the PES payload at which number_of_composition_objects
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// lives in a PCS: 3-byte segment header + 10 bytes of PCS fields
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// (video_w/h, frame_rate, comp_num, comp_state, palette_update,
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// palette_id_ref) = 13.
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const PCS_NUM_OBJECTS_OFFSET: usize = 13;
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pub struct PgsParser {
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pending: Option<(i64, Vec<u8>)>,
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}
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impl Default for PgsParser {
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fn default() -> Self {
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@@ -16,7 +36,7 @@ impl Default for PgsParser {
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impl PgsParser {
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pub fn new() -> Self {
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Self
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Self { pending: None }
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}
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}
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@@ -26,11 +46,63 @@ impl CodecParser for PgsParser {
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return Vec::new();
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}
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let pts_ns = pes.pts.map(pts_to_ns).unwrap_or(0);
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vec![Frame {
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pts_ns,
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keyframe: true,
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data: pes.data.clone(),
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}]
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let is_pcs = pes.data[0] == SEGMENT_PCS;
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let pcs_num_objects = if is_pcs && pes.data.len() > PCS_NUM_OBJECTS_OFFSET {
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Some(pes.data[PCS_NUM_OBJECTS_OFFSET])
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} else {
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None
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};
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let mut out = Vec::new();
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match pcs_num_objects {
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// Clear/empty PCS — closes any pending display. Drop the
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// clear segment itself; BlockDuration covers the screen
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// wipe.
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Some(0) => {
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if let Some((start_pts, data)) = self.pending.take() {
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let duration = pts_ns.saturating_sub(start_pts).max(0) as u64;
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out.push(Frame {
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pts_ns: start_pts,
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keyframe: true,
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data,
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duration_ns: Some(duration),
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});
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}
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}
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// Display PCS — start a new pending. If a prior display
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// was never explicitly cleared (replace-without-clear),
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// emit it with the new PCS's PTS as its end.
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Some(_) => {
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if let Some((start_pts, data)) = self.pending.take() {
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let duration = pts_ns.saturating_sub(start_pts).max(0) as u64;
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out.push(Frame {
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pts_ns: start_pts,
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keyframe: true,
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data,
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duration_ns: Some(duration),
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});
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}
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self.pending = Some((pts_ns, pes.data.clone()));
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}
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// Non-PCS first segment — either a continuation of the
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// current display set, or non-standard layout. If we have
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// a pending display, append; otherwise emit as-is.
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None => {
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if let Some((_, ref mut buf)) = self.pending {
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buf.extend_from_slice(&pes.data);
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} else {
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out.push(Frame {
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pts_ns,
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keyframe: true,
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data: pes.data.clone(),
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duration_ns: None,
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});
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}
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}
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}
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out
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}
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fn codec_private(&self) -> Option<Vec<u8>> {
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@@ -52,29 +124,60 @@ mod tests {
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}
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}
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#[test]
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fn parse_basic_segment() {
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let mut parser = PgsParser::new();
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// PGS segment data (PCS = presentation composition segment)
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let data = vec![0x16, 0x00, 0x00, 0x11, 0x01, 0x02, 0x03];
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let pes = make_pes(data.clone(), Some(90000));
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let frames = parser.parse(&pes);
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assert_eq!(frames.len(), 1);
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assert_eq!(frames[0].data, data);
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assert_eq!(frames[0].pts_ns, 1_000_000_000);
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// Minimum-viable PCS bytes: type 0x16, segment_length (2 bytes),
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// then 11 bytes of PCS fields ending in number_of_composition_objects.
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fn pcs_bytes(num_objects: u8) -> Vec<u8> {
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let mut v = vec![SEGMENT_PCS, 0x00, 0x0B];
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v.extend_from_slice(&[0x07, 0x80, 0x04, 0x38]); // 1920x1080
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v.push(0x10); // frame_rate
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v.extend_from_slice(&[0x00, 0x01]); // composition_number
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v.push(0x80); // composition_state = EpochStart
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v.push(0x00); // palette_update + reserved
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v.push(0x00); // palette_id_ref
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v.push(num_objects);
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v
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}
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#[test]
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fn all_keyframes() {
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fn display_then_clear_yields_duration() {
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let mut parser = PgsParser::new();
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for i in 0..3 {
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let data = vec![0x16, 0x00, i];
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let pes = make_pes(data, Some(90000 * i as i64));
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let frames = parser.parse(&pes);
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assert_eq!(frames.len(), 1);
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assert!(frames[0].keyframe, "PGS segment should always be keyframe");
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}
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// Display PCS at PTS 90000 (= 1s)
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let display = pcs_bytes(1);
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let frames = parser.parse(&make_pes(display.clone(), Some(90000)));
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assert!(frames.is_empty(), "display PCS should be pending");
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// Empty PCS at PTS 270000 (= 3s)
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let clear = pcs_bytes(0);
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let frames = parser.parse(&make_pes(clear, Some(270000)));
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assert_eq!(frames.len(), 1);
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assert_eq!(frames[0].pts_ns, 1_000_000_000);
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assert_eq!(frames[0].duration_ns, Some(2_000_000_000));
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assert_eq!(frames[0].data, display);
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}
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#[test]
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fn replace_without_clear_still_emits_prior_with_duration() {
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let mut parser = PgsParser::new();
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let _ = parser.parse(&make_pes(pcs_bytes(1), Some(90000)));
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let frames = parser.parse(&make_pes(pcs_bytes(1), Some(180000)));
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assert_eq!(frames.len(), 1);
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assert_eq!(frames[0].pts_ns, 1_000_000_000);
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assert_eq!(frames[0].duration_ns, Some(1_000_000_000));
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}
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#[test]
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fn non_pcs_segment_appends_to_pending() {
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let mut parser = PgsParser::new();
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let _ = parser.parse(&make_pes(pcs_bytes(1), Some(90000)));
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// ODS-like segment (type 0x15)
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let frames = parser.parse(&make_pes(vec![0x15, 0x00, 0x02, 0xAA, 0xBB], Some(90000)));
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assert!(frames.is_empty());
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// Clear closes the set; data should include the appended bytes.
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let frames = parser.parse(&make_pes(pcs_bytes(0), Some(180000)));
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assert_eq!(frames.len(), 1);
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let data = &frames[0].data;
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assert!(data.windows(5).any(|w| w == [0x15, 0x00, 0x02, 0xAA, 0xBB]));
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}
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#[test]
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