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Increasing max video cache frames, moving percentage-ahead caching to a setting, fixing a calculation error on bytes per frame

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This commit is contained in:
Jonathan Thomas
2022-09-20 16:55:07 -05:00
parent 16dc5408cc
commit 969a2015bf
4 changed files with 40 additions and 14 deletions
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43
src/Qt/VideoCacheThread.cpp
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@@ -78,6 +78,19 @@ namespace openshot
Seek(new_position);
}
// Get the size in bytes of a frame (rough estimate)
int64_t VideoCacheThread::getBytes(int width, int height, int sample_rate, int channels, float fps)
{
int64_t total_bytes = 0;
total_bytes += static_cast<int64_t>(width * height * sizeof(char) * 4);
// approximate audio size (sample rate / 24 fps)
total_bytes += ((sample_rate * channels) / fps) * sizeof(float);
// return size of this frame
return total_bytes;
}
// Play the video
void VideoCacheThread::Play() {
// Start playing
@@ -98,14 +111,14 @@ namespace openshot
// Start the thread
void VideoCacheThread::run()
{
// Get settings
Settings *s = Settings::Instance();
// 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>;
while (!threadShouldExit() && is_playing) {
// Get settings
Settings *s = Settings::Instance();
// init local vars
min_frames_ahead = s->VIDEO_CACHE_MIN_PREROLL_FRAMES;
max_frames_ahead = s->VIDEO_CACHE_MAX_PREROLL_FRAMES;
@@ -137,18 +150,24 @@ namespace openshot
// To allow the cache to fill-up only on the initial pause.
should_pause_cache = 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 bytes per frame
int64_t bytes_per_frame = getBytes(reader->info.width, reader->info.height,
reader->info.sample_rate, reader->info.channels,
reader->info.fps.ToFloat());
Timeline *t = (Timeline *) reader;
if (t->preview_width != reader->info.width || t->preview_height != reader->info.height) {
// If we have a different timeline preview size, use that instead (the preview
// window can be smaller, can thus reduce the bytes per frame)
bytes_per_frame = getBytes(t->preview_width, t->preview_height,
reader->info.sample_rate, reader->info.channels,
reader->info.fps.ToFloat());
}
// 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;
// When paused, limit the cached frames to the following % of total cache size.
// This allows for us to leave some cache behind the plahead, and some in front of the playhead.
max_frames_ahead = (reader->GetCache()->GetMaxBytes() / bytes_per_frame) * s->VIDEO_CACHE_PERCENT_AHEAD;
if (max_frames_ahead > s->VIDEO_CACHE_MAX_FRAMES) {
// Ignore values that are too large, and default to a safer value
max_frames_ahead = s->VIDEO_CACHE_MAX_FRAMES;
@@ -222,7 +241,7 @@ namespace openshot
if (current_speed != speed) {
break;
}
// Check if playback has stopped
// Check if thread has stopped
if (!is_playing) {
break;
}