On Mon, Jul 25, 2016 at 11:04 PM, Chao Liu <yijin...@gmail.com> wrote:
> Hi, > > (Ivan, I am sending this mail to you directly because you said you are the > maintainer of QSV related code in a recent mail. Apologize if this is > inappropriate.. ) > > I am trying to use h264_qsv to transcode a MP4 file. This is my command: > ffmpeg -c:v h264_qsv -i input.mp4 -look_ahead 0 -c:v h264_qsv -b:v 800k > -maxrate 1600k -preset fast output.mp4 > It always stucks in this loop > <https://github.com/FFmpeg/FFmpeg/blob/master/libavcodec/qsvenc.c#L970>. > > It works if I change the command to > ffmpeg -i input.mp4 -look_ahead 0 -c:v h264_qsv -b:v 800k -maxrate 1600k > -preset fast output.mp4 > (not using qsv for decoding). > > Looks like the decoding and encoding were contending for the resources and > there is a deadlock or sth. like that.. > > I tried to debug it a bit by comparing ffmpeg code with intel media SDK. > There is sth. I don't understand. Not sure whether it's related.. > In ffmpeg, we decode the frame in a loop > <https://github.com/FFmpeg/FFmpeg/blob/master/libavcodec/qsvdec.c#L357>, > it sleeps and retries as long as MFXVideoDECODE_DecodeFrameAsync returns > busy. > In intel media SDK sample_decode, it calls SyncOperation when > MFXVideoDECODE_DecodeFrameAsync returns busy. > Sorry, forgot to paste the link to the code https://github.com/Intel-Media-SDK/samples/blob/master/samples/sample_decode/src/pipeline_decode.cpp#L1631 > > Could this be the cause? > _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
