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LibVideo: Read Matroska lazily so that large files can start quickly

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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.
This commit is contained in:
Zaggy1024 2022-11-11 17:14:27 -06:00 • committed by Andreas Kling
parent f4c476b26f
commit 393cfdd5c5
11 changed files with 576 additions and 310 deletions
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61
Userland/Libraries/LibVideo/Containers/Matroska/Document.h
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@ -150,8 +150,6 @@ public:
EBML = 0b11,
};
Block() = default;
u64 track_number() const { return m_track_number; }
void set_track_number(u64 track_number) { m_track_number = track_number; }
i16 timestamp() const { return m_timestamp; }
@ -164,10 +162,11 @@ public:
void set_lacing(Lacing lacing) { m_lacing = lacing; }
bool discardable() const { return m_discardable; }
void set_discardable(bool discardable) { m_discardable = discardable; }
void set_frames(Vector<ReadonlyBytes>&& frames) { m_frames = move(frames); }
ReadonlyBytes const& frame(size_t index) const { return frames()[index]; }
u64 frame_count() const { return m_frames.size(); }
Vector<ByteBuffer> const& frames() const { return m_frames; }
ByteBuffer const& frame(size_t index) const { return frames()[index]; }
void add_frame(ByteBuffer frame) { m_frames.append(move(frame)); }
Vector<ReadonlyBytes> const& frames() const { return m_frames; }
private:
u64 m_track_number { 0 };
@ -176,64 +175,16 @@ private:
bool m_invisible { false };
Lacing m_lacing { None };
bool m_discardable { true };
Vector<ByteBuffer> m_frames;
Vector<ReadonlyBytes> m_frames;
};
class Cluster {
public:
u64 timestamp() const { return m_timestamp; }
void set_timestamp(u64 timestamp) { m_timestamp = timestamp; }
NonnullOwnPtrVector<Block>& blocks() { return m_blocks; }
NonnullOwnPtrVector<Block> const& blocks() const { return m_blocks; }
private:
u64 m_timestamp { 0 };
NonnullOwnPtrVector<Block> m_blocks;
};
class MatroskaDocument {
public:
explicit MatroskaDocument(EBMLHeader m_header)
: m_header(move(m_header))
{
}
EBMLHeader const& header() const { return m_header; }
Optional<SegmentInformation> segment_information() const
{
if (!m_segment_information)
return {};
return *m_segment_information;
}
void set_segment_information(OwnPtr<SegmentInformation> segment_information) { m_segment_information = move(segment_information); }
HashMap<u64, NonnullOwnPtr<TrackEntry>> const& tracks() const { return m_tracks; }
Optional<TrackEntry> track_for_track_number(u64 track_number) const
{
auto track = m_tracks.get(track_number);
if (!track.has_value())
return {};
return *track.value();
}
Optional<TrackEntry> track_for_track_type(TrackEntry::TrackType type) const
{
for (auto& track_entry : m_tracks) {
if (track_entry.value->track_type() == type)
return *track_entry.value;
}
return {};
}
void add_track(u64 track_number, NonnullOwnPtr<TrackEntry> track)
{
m_tracks.set(track_number, move(track));
}
NonnullOwnPtrVector<Cluster>& clusters() { return m_clusters; }
private:
EBMLHeader m_header;
OwnPtr<SegmentInformation> m_segment_information;
HashMap<u64, NonnullOwnPtr<TrackEntry>> m_tracks;
NonnullOwnPtrVector<Cluster> m_clusters;
u64 m_timestamp;
};
}