Well,Hendrik is right. The decoder knows to detect that the YUV is NV12. I do get the decoded YUV correct now,but not for the first frame.For some reason the first frame has completely green color. I do tell the NVENC to set SPSPPS at the beginning, but still the first frame gets corrupted. Also, how do I flip the frame vertically on decoding ?
On Jul 31, 2017 2:07 PM, "jing zhang" <zhangjing...@gmail.com> wrote: You should use decoded AVFrame->format to check decoded yuv format. Maybe H.264 bitstream encoded by NVENC is corrupted? 2017-07-31 16:27 GMT+08:00 Michael IV <explomas...@gmail.com>: > So you basically say that the decoder 'knows' to detect interleaved UV in > NV12 UV plane and decode it correctly to yuv420p without any hints from the > application? > Then why my YUV frame is corrupted? How can I detect where is the problem? > I also found this SO answer regarding h264 streaming from NVENC. > https://stackoverflow.com/questions/33185966/how-to-stream- > h-264-video-over-udp-using-the-nvidia-nvenc-hardware-encoder > > And I currently don't set those params for encoder.Do I have to? > > > On Mon, Jul 31, 2017 at 11:04 AM, Hendrik Leppkes <h.lepp...@gmail.com> > wrote: > >> On Mon, Jul 31, 2017 at 10:00 AM, Michael IV <explomas...@gmail.com> >> wrote: >> > Hi! I am using NVENC encoder to create h264 stream.The YUV format is >> NV12. >> > Now, I need also to decode that stream back to YUV.I wrote a module for >> > that,based on >> > this example: >> > >> > https://gist.github.com/roxlu/9329339 >> > >> > But, because my YUV format is not 420P, but NV12 I am trying to force >> it on >> > AVCodecContext when initializing it with this line: >> > >> > avcodec_register_all(); >> > mCodec = avcodec_find_decoder(AV_CODEC_ID_H264); >> > mCodecContext = avcodec_alloc_context3(mCodec); >> > mCodecContext->pix_fmt = AVPixelFormat::AV_PIX_FMT_NV12; >> > >> > >> > But when I am receiving the decoded AVFrame, I see that the >> AVFrame->format >> > property is >> > set to zero, which is enum for 420P. Also inspecting the planes and >> other >> > props of this struct I see that the decoder tried to decode it as 420P. >> (3 >> > planes , 3 line sizes etc.) .And of course,when trying to play the >> output of >> > such a YUV frame , there is just a green screen. >> > I am trying to understand where is my error.Is there some data that >> decoder >> > misses from the h264 stream and it doesn't allow it to guess the pixel >> > format?Or maybe I need to set pixel format for the codec context in a >> some >> > different way? >> > >> >> You can't control the output pixel format of the H264 decoder. A video >> is not encoded as "NV12", its encoded as 4:2:0 YUV, NV12 is just one >> representation of this format. >> As such, our decoder will always decode 4:2:0 YUV content to yuv420p, >> not nv12. If you require NV12 in your application, you can convert >> from yuv420p to nv12 using swscale (a lossless conversion). >> >> - Hendrik >> _______________________________________________ >> Libav-user mailing list >> Libav-user@ffmpeg.org >> http://ffmpeg.org/mailman/listinfo/libav-user >> > > > _______________________________________________ > Libav-user mailing list > Libav-user@ffmpeg.org > http://ffmpeg.org/mailman/listinfo/libav-user > > _______________________________________________ Libav-user mailing list Libav-user@ffmpeg.org http://ffmpeg.org/mailman/listinfo/libav-user
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