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foundations for background caching

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This commit is contained in:
itsmattkc
2019-08-24 22:16:01 +10:00
parent 9439494c10
commit 438e7081f9
39 changed files with 919 additions and 213 deletions
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app/decoder/ffmpeg/ffmpegdecoder.cpp
+13 -7
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@@ -211,24 +211,30 @@ FramePtr FFmpegDecoder::Retrieve(const rational &timecode, const rational &lengt
// Set up seeking loop
int64_t seek_ts = target_ts;
int64_t second_ts = qRound(rational(avstream_->time_base).flipped().toDouble());
bool last_backtrack = false;
// FFmpeg frame retrieve loop
while (ret >= 0 && frame_->pts != target_ts) {
// If the frame timestamp is too large, we need to seek back a little
if (frame_->pts > target_ts || frame_->pts == AV_NOPTS_VALUE) {
avcodec_flush_buffers(codec_ctx_);
av_seek_frame(fmt_ctx_, avstream_->index, seek_ts, AVSEEK_FLAG_BACKWARD);
// FFmpeg doesn't always seek correctly, if we have to seek again we wrangle it into seeking back far enough
// If we already tried seeking to 0 though, there's nothing we can do so we error here
if (seek_ts == 0) {
if (last_backtrack) {
Error(tr("FFmpeg failed to seek to the correct location"));
return nullptr;
}
seek_ts = qMax(0L, seek_ts - second_ts);
// We can't seek earlier than 0, so if this is a 0-seek, don't try any more times after this attempt
if (seek_ts <= 0) {
seek_ts = 0;
last_backtrack = true;
}
avcodec_flush_buffers(codec_ctx_);
av_seek_frame(fmt_ctx_, avstream_->index, seek_ts, AVSEEK_FLAG_BACKWARD);
// FFmpeg doesn't always seek correctly, if we have to seek again we wrangle it into seeking back far enough
seek_ts -= second_ts;
}
ret = GetFrame();