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isomp4: Use the track ID from the container.
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Fixes #324.
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@pdeljanov
pdeljanov committed Oct 25, 2024
1 parent dc287cc commit 1cb82d8
Showing 1 changed file with 53 additions and 34 deletions.
87 changes: 53 additions & 34 deletions symphonia-format-isomp4/src/demuxer.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -7,7 +7,9 @@

use symphonia_core::support_format;

use symphonia_core::errors::{decode_error, seek_error, unsupported_error, Result, SeekErrorKind};
use symphonia_core::errors::{
decode_error, seek_error, unsupported_error, Error, Result, SeekErrorKind,
};
use symphonia_core::formats::prelude::*;
use symphonia_core::formats::probe::{ProbeFormatData, ProbeableFormat, Score, Scoreable};
use symphonia_core::formats::well_known::FORMAT_ID_ISOMP4;
Expand All @@ -33,6 +35,8 @@ const ISOMP4_FORMAT_INFO: FormatInfo = FormatInfo {
pub struct TrackState {
/// The track number.
track_num: usize,
/// The track ID.
track_id: u32,
/// The current segment.
cur_seg: usize,
/// The current sample index relative to the track.
Expand All @@ -42,12 +46,8 @@ pub struct TrackState {
}

impl TrackState {
pub fn new(track_num: usize) -> Self {
Self { track_num, cur_seg: 0, next_sample: 0, next_sample_pos: 0 }
}

pub fn make_track(&self, trak: &TrakAtom) -> Track {
let mut track = Track::new(self.track_num as u32);
pub fn make(track_num: usize, trak: &TrakAtom) -> (Self, Track) {
let mut track = Track::new(trak.tkhd.id);

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@sscobici

sscobici Dec 30, 2024

This change is not complete.

Packet object has just id field. Now when this id means a value from container, not the index. It's not easy to find the corresponding packet's track in the external application.

for example this code has issues:
let video_track_id = format.first_track(TrackType::Video); // returns 1 starting from 1
let track = format.tracks().get(packet.track_id()) // WRONG, returns Audio track which has track_id = 2

I think it will be good to have both track_id and track_num in core objects.
@pdeljanov

// Create the codec parameters using the sample description atom.
if let Some(codec_params) = trak.mdia.minf.stbl.stsd.make_codec_params() {
Expand All @@ -58,7 +58,15 @@ impl TrackState {
.with_time_base(TimeBase::new(1, trak.mdia.mdhd.timescale))
.with_num_frames(trak.duration);

track
let state = Self {
track_num,
track_id: trak.tkhd.id,
cur_seg: 0,
next_sample: 0,
next_sample_pos: 0,
};

(state, track)
}
}

Expand All @@ -67,6 +75,8 @@ impl TrackState {
struct NextSampleInfo {
/// The track number of the next sample.
track_num: usize,
/// The track id.
track_id: u32,
/// The timestamp of the next sample.
ts: u64,
/// The timestamp expressed in seconds.
Expand Down Expand Up @@ -234,15 +244,16 @@ impl<'s> IsoMp4Reader<'s> {
metadata.push(rev);
}

// Instantiate a `TrackState` for each track in the media.
let track_states = (0..moov.traks.len()).map(TrackState::new).collect::<Vec<TrackState>>();
// Create a track and track state for each Track (trak) atom.
let mut tracks = Vec::with_capacity(moov.traks.len());
let mut track_states = Vec::with_capacity(moov.traks.len());

for (t, trak) in moov.traks.iter().enumerate() {
let (track_state, track) = TrackState::make(t, trak);

// Instantiate a `Track` for all track states above.
let tracks = track_states
.iter()
.zip(&moov.traks)
.map(|(state, trak)| state.make_track(trak))
.collect();
tracks.push(track);
track_states.push(track_state);
}

// The number of tracks specified in the moov atom must match the number in the mvex atom.
if let Some(mvex) = &moov.mvex {
Expand Down Expand Up @@ -282,9 +293,7 @@ impl<'s> IsoMp4Reader<'s> {
// Compare the presentation time of the sample from this track to other tracks,
// and select the track with the earliest presentation time.
match earliest {
Some(NextSampleInfo { track_num: _, ts: _, time, dur: _, seg_idx: _ })
if time <= sample_time =>
{
Some(NextSampleInfo { time, .. }) if time <= sample_time => {
// Earliest is less than or equal to the track's next sample
// presentation time. No need to update earliest.
}
Expand All @@ -293,6 +302,7 @@ impl<'s> IsoMp4Reader<'s> {
// presentation time. Update earliest.
earliest = Some(NextSampleInfo {
track_num: state.track_num,
track_id: state.track_id,
ts: timing.ts,
time: sample_time,
dur: timing.dur,
Expand Down Expand Up @@ -410,7 +420,7 @@ impl<'s> IsoMp4Reader<'s> {
}

fn seek_track_by_ts(&mut self, track_num: usize, ts: u64) -> Result<SeekedTo> {
debug!("seeking track={} to frame_ts={}", track_num, ts);
debug!("seeking track_num={} to frame_ts={}", track_num, ts);

struct SeekLocation {
seg_idx: usize,
Expand Down Expand Up @@ -461,13 +471,14 @@ impl<'s> IsoMp4Reader<'s> {
let timing = seg.sample_timing(track_num, seek_loc.sample_num)?.unwrap();

debug!(
"seeked track={} to packet_ts={} (delta={})",
"seeked track_num={} (track_id={}) to packet_ts={} (delta={})",
track_num,
track.track_id,
timing.ts,
timing.ts as i64 - ts as i64
);

Ok(SeekedTo { track_id: track_num as u32, required_ts: ts, actual_ts: timing.ts })
Ok(SeekedTo { track_id: track.track_id, required_ts: ts, actual_ts: timing.ts })
}
else {
// Timestamp was not found.
Expand Down Expand Up @@ -548,7 +559,7 @@ impl FormatReader for IsoMp4Reader<'_> {
}

Ok(Some(Packet::new_from_boxed_slice(
next_sample_info.track_num as u32,
next_sample_info.track_id,
next_sample_info.ts,
u64::from(next_sample_info.dur),
reader.read_boxed_slice_exact(sample_info.len as usize)?,
Expand All @@ -570,42 +581,50 @@ impl FormatReader for IsoMp4Reader<'_> {

match to {
SeekTo::TimeStamp { ts, track_id } => {
let selected_track_id = track_id as usize;

// The seek timestamp is in timebase units specific to the selected track. Get the
// selected track and use the timebase to convert the timestamp into time units so
// that the other tracks can be seeked.
if let Some(selected_track) = self.tracks().get(selected_track_id) {
if let Some((track_num, track)) =
self.tracks.iter().enumerate().find(|(_, track)| track.id == track_id)
{
// Convert to time units.
let time = selected_track.time_base.unwrap().calc_time(ts);
let time = track.time_base.unwrap().calc_time(ts);

// Seek all tracks excluding the primary track to the desired time.
for t in 0..self.track_states.len() {
if t != selected_track_id {
if t != track_num {
self.seek_track_by_time(t, time)?;
}
}

// Seek the primary track and return the result.
self.seek_track_by_ts(selected_track_id, ts)
self.seek_track_by_ts(track_num, ts)
}
else {
seek_error(SeekErrorKind::Unseekable)
seek_error(SeekErrorKind::InvalidTrack)
}
}
SeekTo::Time { time, track_id } => {
// Select the first track if a selected track was not provided.
let selected_track_id = track_id.unwrap_or(0) as usize;
// If provided, find the track number of the track with the desired track_id, or
// default to the first track.
let track_num = match track_id {
Some(id) => self
.tracks
.iter()
.position(|track| track.id == id)
.ok_or(Error::SeekError(SeekErrorKind::InvalidTrack))?,
None => 0,
};

// Seek all tracks excluding the selected track and discard the result.
for t in 0..self.track_states.len() {
if t != selected_track_id {
if t != track_num {
self.seek_track_by_time(t, time)?;
}
}

// Seek the primary track and return the result.
self.seek_track_by_time(selected_track_id, time)
self.seek_track_by_time(track_num, time)
}
}
}
Expand Down

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