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serenity/Userland/Libraries/LibVideo/Containers/Matroska/MatroskaDemuxer.cpp
Zaggy1024 393cfdd5c5 LibVideo: Read Matroska lazily so that large files can start quickly
The Demuxer class was changed to return errors for more functions so
that all of the underlying reading can be done lazily. Other than that,
the demuxer interface is unchanged, and only the underlying reader was
modified.

The MatroskaDocument class is no more, and MatroskaReader's getter
functions replace it. Every MatroskaReader getter beyond the Segment
element's position is parsed lazily from the file as needed. This means
that all getter functions can return DecoderErrors which must be
handled by callers.
2022-11-25 23:28:39 +01:00

91 lines
3.2 KiB
C++

/*
* Copyright (c) 2022, Gregory Bertilson <zaggy1024@gmail.com>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include "MatroskaDemuxer.h"
namespace Video::Matroska {
DecoderErrorOr<NonnullOwnPtr<MatroskaDemuxer>> MatroskaDemuxer::from_file(StringView filename)
{
return make<MatroskaDemuxer>(TRY(Reader::from_file(filename)));
}
DecoderErrorOr<NonnullOwnPtr<MatroskaDemuxer>> MatroskaDemuxer::from_data(ReadonlyBytes data)
{
return make<MatroskaDemuxer>(TRY(Reader::from_data(data)));
}
DecoderErrorOr<Vector<Track>> MatroskaDemuxer::get_tracks_for_type(TrackType type)
{
TrackEntry::TrackType matroska_track_type;
switch (type) {
case TrackType::Video:
matroska_track_type = TrackEntry::TrackType::Video;
break;
case TrackType::Audio:
matroska_track_type = TrackEntry::TrackType::Audio;
break;
case TrackType::Subtitles:
matroska_track_type = TrackEntry::TrackType::Subtitle;
break;
}
Vector<Track> tracks;
TRY(m_reader.for_each_track_of_type(matroska_track_type, [&](TrackEntry const& track_entry) -> DecoderErrorOr<IterationDecision> {
VERIFY(track_entry.track_type() == matroska_track_type);
DECODER_TRY_ALLOC(tracks.try_append(Track(type, track_entry.track_number())));
return IterationDecision::Continue;
}));
return tracks;
}
DecoderErrorOr<MatroskaDemuxer::TrackStatus*> MatroskaDemuxer::get_track_status(Track track)
{
if (!m_track_statuses.contains(track)) {
auto iterator = TRY(m_reader.create_sample_iterator(track.identifier()));
DECODER_TRY_ALLOC(m_track_statuses.try_set(track, { iterator }));
}
return &m_track_statuses.get(track).release_value();
}
DecoderErrorOr<void> MatroskaDemuxer::seek_to_most_recent_keyframe(Track track, size_t timestamp)
{
if (timestamp == 0) {
// Removing the track status will cause us to start from the beginning.
m_track_statuses.remove(track);
return {};
}
return DecoderError::not_implemented();
}
DecoderErrorOr<NonnullOwnPtr<Sample>> MatroskaDemuxer::get_next_sample_for_track(Track track)
{
// FIXME: This makes a copy of the sample, which shouldn't be necessary.
// Matroska should make a RefPtr<ByteBuffer>, probably.
auto& status = *TRY(get_track_status(track));
if (!status.block.has_value() || status.frame_index >= status.block->frame_count()) {
status.block = TRY(status.iterator.next_block());
status.frame_index = 0;
}
auto const& cluster = status.iterator.current_cluster();
Time timestamp = Time::from_nanoseconds((cluster.timestamp() + status.block->timestamp()) * TRY(m_reader.segment_information()).timestamp_scale());
auto cicp = TRY(m_reader.track_for_track_number(track.identifier())).video_track()->color_format.to_cicp();
return make<VideoSample>(status.block->frame(status.frame_index++), cicp, timestamp);
}
DecoderErrorOr<Time> MatroskaDemuxer::duration()
{
auto segment_information = TRY(m_reader.segment_information());
if (!segment_information.duration().has_value())
return Time::zero();
return Time::from_nanoseconds(static_cast<i64>(segment_information.duration().value() * segment_information.timestamp_scale()));
}
}