private void readDecodedFrames(AVFrame *receiveFrame)
{
while (true)
{
int receiveFrameResult = ffmpeg.avcodec_receive_frame(codecContext, receiveFrame);
if (receiveFrameResult < 0)
{
if (receiveFrameResult != -AGffmpeg.EAGAIN && receiveFrameResult != AGffmpeg.AVERROR_EOF)
{
Logger.Log($"Failed to receive frame from avcodec: {getErrorMessage(receiveFrameResult)}");
}
break;
}
// use `best_effort_timestamp` as it can be more accurate if timestamps from the source file (pts) are broken.
// but some HW codecs don't set it in which case fallback to `pts`
long frameTimestamp = receiveFrame->best_effort_timestamp != AGffmpeg.AV_NOPTS_VALUE ? receiveFrame->best_effort_timestamp : receiveFrame->pts;
double frameTime = (frameTimestamp - stream->start_time) * timeBaseInSeconds * 1000;
if (skipOutputUntilTime > frameTime)
{
continue;
}
// get final frame.
FFmpegFrame frame;
if (((AVPixelFormat)receiveFrame->format).IsHardwarePixelFormat())
{
// transfer data from HW decoder to RAM.
if (!hwTransferFrames.TryDequeue(out var hwTransferFrame))
{
hwTransferFrame = new FFmpegFrame(ffmpeg, returnHwTransferFrame);
}
// WARNING: frames from `av_hwframe_transfer_data` have their timestamps set to AV_NOPTS_VALUE instead of real values.
// if you need to use them later, take them from `receiveFrame`.
int transferResult = ffmpeg.av_hwframe_transfer_data(hwTransferFrame.Pointer, receiveFrame, 0);
if (transferResult < 0)
{
Logger.Log($"Failed to transfer frame from HW decoder: {getErrorMessage(transferResult)}");
// dispose of the frame instead of enqueueing it in case that the failure was caused by it's configuration.
hwTransferFrame.Dispose();
continue;
}
frame = hwTransferFrame;
}
else
{
// copy data to a new AVFrame so that `receiveFrame` can be reused.
frame = new FFmpegFrame(ffmpeg);
ffmpeg.av_frame_move_ref(frame.Pointer, receiveFrame);
}
lastDecodedFrameTime = (float)frameTime;
// Note: this is the pixel format that `VideoTexture` expects internally
frame = ensureFramePixelFormat(frame, AVPixelFormat.AV_PIX_FMT_YUV420P);
if (frame == null)
{
continue;
}
if (!availableTextures.TryDequeue(out var tex))
{
tex = new Texture(new VideoTexture(frame.Pointer->width, frame.Pointer->height));
}
var upload = new VideoTextureUpload(frame);
tex.SetData(upload);
decodedFrames.Enqueue(new DecodedFrame {
Time = frameTime, Texture = tex
});
}
}