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Allow cache on initial pause, to use the Timeline cache size to initially cache a bunch more frames... and then fully pause. This allows for a balance between not-caching during pause (for Transform and Scrubbing performance), but still caching frames on pause so the user can wait for a smoother playback experience.

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This commit is contained in:
Jonathan Thomas
2022-02-28 15:45:46 -06:00
parent 64815d6bae
commit c71a1af6ea
2 changed files with 42 additions and 3 deletions
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40
src/Qt/VideoCacheThread.cpp
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@@ -74,6 +74,7 @@ namespace openshot
// Types for storing time durations in whole and fractional microseconds
using micro_sec = std::chrono::microseconds;
using double_micro_sec = std::chrono::duration<double, micro_sec::period>;
bool should_pause = false;
while (!threadShouldExit() && is_playing) {
// Calculate on-screen time for a single frame
@@ -83,9 +84,46 @@ namespace openshot
// Calculate increment (based on speed)
// Support caching in both directions
int16_t increment = speed;
if (speed == 0) {
if (current_speed == 0 && should_pause) {
// Sleep during pause (after caching additional frames when paused)
std::this_thread::sleep_for(frame_duration / 4);
continue;
} else if (current_speed == 0) {
// Allow 'max frames' to increase when pause is detected (based on cache)
// To allow the cache to fill-up only on the initial pause.
should_pause = true;
// Calculate bytes per frame. If we have a reference openshot::Frame, use that instead (the preview
// window can be smaller, can thus reduce the bytes per frame)
int64_t bytes_per_frame = (reader->info.height * reader->info.width * 4) +
(reader->info.sample_rate * reader->info.channels * 4);
if (last_cached_frame && last_cached_frame->has_image_data && last_cached_frame->has_audio_data) {
bytes_per_frame = last_cached_frame->GetBytes();
}
// Calculate # of frames on Timeline cache (when paused)
if (reader->GetCache() && reader->GetCache()->GetMaxBytes() > 0) {
// When paused, use 1/2 the cache size (so our cache will be 50% before the play-head, and 50% after it)
max_frames_ahead = (reader->GetCache()->GetMaxBytes() / bytes_per_frame) / 2;
if (max_frames_ahead > 300) {
// Ignore values that are too large, and default to a safer value
max_frames_ahead = 300;
}
}
// Overwrite the increment to our cache position
// to fully cache frames while paused (support forward and rewind)
if (last_speed > 0) {
increment = 1;
} else {
increment = -1;
}
} else {
// Default max frames ahead (normal playback)
max_frames_ahead = 8;
should_pause = false;
}
// Always cache frames from the current display position to our maximum (based on the cache size).