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LibVideo: Pass the current sample to demuxers to lazily seek better

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In cases where the PlaybackManager's earliest buffered or displayed
sample is closer to the seek target than the demuxer's chosen keyframe,
we don't want to seek at all. To enable this, demuxers now receive an
optional parameter with the earliest timestamp that the caller can
still access.

The demuxer in turn returns an optional to indicate when a seek was not
needed, which allows PlaybackManager to avoid clearing its queue and
re-decoding frames.
This commit is contained in:
Zaggy1024 2023-02-06 01:25:02 -06:00 • committed by Andreas Kling
parent 275d57eb6f
commit 3bfef8bfe0
7 changed files with 61 additions and 42 deletions
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32
Userland/Libraries/LibVideo/PlaybackManager.cpp
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@ -114,11 +114,11 @@ void PlaybackManager::seek_to_timestamp(Time target_timestamp)
TRY_OR_FATAL_ERROR(m_playback_handler->seek(target_timestamp, m_seek_mode));
}
Time PlaybackManager::seek_demuxer_to_most_recent_keyframe(Time timestamp)
Optional<Time> PlaybackManager::seek_demuxer_to_most_recent_keyframe(Time timestamp, Optional<Time> earliest_available_sample)
{
// FIXME: When the demuxer is getting samples off the main thread in the future, this needs to
// mutex so that seeking can't happen while that thread is getting a sample.
auto result = m_demuxer->seek_to_most_recent_keyframe(m_selected_video_track, timestamp);
auto result = m_demuxer->seek_to_most_recent_keyframe(m_selected_video_track, timestamp, move(earliest_available_sample));
if (result.is_error())
on_decoder_error(result.release_error());
return result.release_value();
@ -459,18 +459,30 @@ private:
ErrorOr<void> on_enter() override
{
auto keyframe_timestamp = manager().seek_demuxer_to_most_recent_keyframe(m_target_timestamp);
dbgln_if(PLAYBACK_MANAGER_DEBUG, "{} seeking to timestamp target {}ms, selected keyframe at {}ms", m_seek_mode == SeekMode::Accurate ? "Accurate"sv : "Fast"sv, m_target_timestamp.to_milliseconds(), keyframe_timestamp.to_milliseconds());
auto earliest_available_sample = manager().m_last_present_in_media_time;
if (manager().m_next_frame.has_value() && manager().m_next_frame->is_frame()) {
earliest_available_sample = min(earliest_available_sample, manager().m_next_frame->timestamp());
}
auto keyframe_timestamp = manager().seek_demuxer_to_most_recent_keyframe(m_target_timestamp, earliest_available_sample);
#if PLAYBACK_MANAGER_DEBUG
auto seek_mode_name = m_seek_mode == SeekMode::Accurate ? "Accurate"sv : "Fast"sv;
if (keyframe_timestamp.has_value()) {
dbgln("{} seeking to timestamp target {}ms, selected keyframe at {}ms", seek_mode_name, m_target_timestamp.to_milliseconds(), keyframe_timestamp->to_milliseconds());
} else {
dbgln("{} seeking to timestamp target {}ms, demuxer kept its iterator position", seek_mode_name, m_target_timestamp.to_milliseconds());
}
#endif
if (m_seek_mode == SeekMode::Fast) {
m_target_timestamp = keyframe_timestamp;
m_target_timestamp = keyframe_timestamp.value_or(earliest_available_sample);
}
if (m_target_timestamp < manager().m_last_present_in_media_time) {
if (keyframe_timestamp.has_value()) {
dbgln_if(PLAYBACK_MANAGER_DEBUG, "Timestamp is earlier than current media time, clearing queue");
manager().m_frame_queue->clear();
manager().m_next_frame.clear();
} else if (manager().m_next_frame.has_value() && manager().m_next_frame.value().timestamp() > m_target_timestamp) {
} else if (m_target_timestamp >= manager().m_last_present_in_media_time && manager().m_next_frame.has_value() && manager().m_next_frame.value().timestamp() > m_target_timestamp) {
manager().m_last_present_in_media_time = m_target_timestamp;
return exit_seek();
}
@ -571,7 +583,11 @@ private:
ErrorOr<void> play() override
{
manager().m_last_present_in_media_time = manager().seek_demuxer_to_most_recent_keyframe(Time::zero());
manager().m_next_frame.clear();
manager().m_frame_queue->clear();
auto start_timestamp = manager().seek_demuxer_to_most_recent_keyframe(Time::zero());
VERIFY(start_timestamp.has_value());
manager().m_last_present_in_media_time = start_timestamp.release_value();
return replace_handler_and_delete_this<PlayingStateHandler>();
}
bool is_playing() override { return false; };