[Libav-user] Memory issues while encoding desktop capture

[Prajna Kandarpa]

Hi folks!

I'm working on an application written in C that makes use of the ffmpeg
libraries to record the desktop on OS X using the avfoundation device. I've
included the relevant parts of the code in this email. Full code can be
found here http://stackoverflow.com/q/29341161/799285. I think I'm doing
everything properly upto the decode encode loop which I've included below.

When I run this program, I'm able to encode about 50-100 frames before I
receive a SIGSEGV. Valgrind analysis can be found here:
http://pastebin.com/MPeRhjhN. For each frame that was encoded, my memory
usage goes up by about 4-6MB so I know something is not being freed
properly. Can I get some feedback on this code? Anything that I've done
wrong? or am using incorrectly? Your help is much appreciated, and if you
ever are in Waterloo, ON, I shall buy you a pint or two.

int frame_count = 0;


while (av_read_frame(inFmtCtx, &inPacket) >= 0) {


  if (inPacket.stream_index == videostream) {


    avcodec_decode_video2(inCodecCtx, inFrame, &frameFinished, &inPacket);


    // 1 Frame might need more than 1 packet to be filled


    if (frameFinished) {


      outFrameYUV = av_frame_alloc();


      uint8_t *buffer = (uint8_t *)av_malloc(numBytes);


      int ret =

          avpicture_fill((AVPicture *)outFrameYUV, buffer, PIX_FMT_YUV420P,


                         inCodecCtx->width, inCodecCtx->height);


      if (ret < 0) {


        printf("%d is return val for fill\n", ret);


        return -1;

      }


      // convert image to YUV


      sws_scale(swsCtx, (uint8_t const *const *)inFrame->data,


                inFrame->linesize, 0, inCodecCtx->height,


                outFrameYUV->data, outFrameYUV->linesize);


      // outFrameYUV now holds the YUV scaled frame/picture


      outFrameYUV->format = outCodecCtx->pix_fmt;


      outFrameYUV->width = outCodecCtx->width;


      outFrameYUV->height = outCodecCtx->height;


      AVPacket pkt;


      int got_output;


      av_init_packet(&pkt);


      pkt.data = NULL;


      pkt.size = 0;


      outFrameYUV->pts = frame_count;


      ret = avcodec_encode_video2(outCodecCtx, &pkt, outFrameYUV,
&got_output);


      if (ret < 0) {


        fprintf(stderr, "Error encoding video frame: %s\n",
av_err2str(ret));


        return -1;

      }


      if (got_output) {


        if (stream->codec->coded_frame->key_frame) {


          pkt.flags |= AV_PKT_FLAG_KEY;

        }


        pkt.stream_index = stream->index;


        if (pkt.pts != AV_NOPTS_VALUE)


          pkt.pts = av_rescale_q(pkt.pts, stream->codec->time_base,

                                 stream->time_base);


        if (pkt.dts != AV_NOPTS_VALUE)


          pkt.dts = av_rescale_q(pkt.dts, stream->codec->time_base,

                                 stream->time_base);


        if (avio_open_dyn_buf(&outFmtCtx->pb) != 0) {


          printf("ERROR: Unable to open dynamic buffer\n");

        }


        ret = av_interleaved_write_frame(outFmtCtx, &pkt);


        unsigned char *pb_buffer;


        int len =

            avio_close_dyn_buf(outFmtCtx->pb, (unsigned char **)&pb_buffer);


        avio_write(outFmtCtx->pb, (unsigned char *)pb_buffer, len);


      } else {


        ret = 0;

      }


      if (ret != 0) {


        fprintf(stderr, "Error while writing video frame: %s\n",

                av_err2str(ret));


        exit(1);

      }


      fprintf(stderr, "encoded frame #%d\n", frame_count);


      frame_count++;


      av_free_packet(&pkt);


      av_frame_unref(outFrameYUV);


      av_free(buffer);

    }

  }


  av_free_packet(&inPacket);

}


av_write_trailer(outFmtCtx);


Here's my ffmpeg library versions:

  ffmpeg version
N-70876-g294bb6c Copyright (c) 2000-2015 the FFmpeg developers

  built with Apple LLVM version 6.0 (clang-600.0.56) (based on LLVM 3.5svn)

  configuration: --prefix=/usr/local --enable-gpl --enable-postproc
--enable-pthreads --enable-libmp3lame --enable-libtheora --enable-libx264
--enable-libvorbis --disable-mmx --disable-ssse3 --disable-armv5te
--disable-armv6 --disable-neon --enable-shared
--disable-static --disable-stripping

  libavutil      54. 20.100 / 54. 20.100

  libavcodec     56. 29.100 / 56. 29.100

  libavformat    56. 26.101 / 56. 26.101

  libavdevice    56.  4.100 / 56.  4.100

  libavfilter     5. 13.101 /  5. 13.101

  libswscale      3.  1.101 /  3.  1.101

  libswresample   1.  1.100 /  1.  1.100

  libpostproc    53.  3.100 / 53.  3.100

Hyper fast Audio and Video encoder

Thanks,

Praj
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