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• avcodec/nvdec : Round up odd width/height values

  24 novembre 2017, par Philip Langdale

  avcodec/nvdec : Round up odd width/height values
  nvdec will not produce odd width/height output, and while this is
  
  basically never an issue with most codecs, due to internal alignment
  
  requirements, you can get odd sized jpegs.
  If an odd-sized jpeg is encountered, nvdec will actually round down
  
  internally and produce output that is slightly smaller. This isn't
  
  the end of the world, as long as you know the output size doesn't
  
  match the original image resolution.
  However, with an hwaccel, we don't know. The decoder controls
  
  the reported output size and the hwaccel cannot change it. I was
  
  able to trigger an error in mpv where it tries to copy the output
  
  surface as part of rendering and triggers a cuda error because
  
  cuda knows the output frame is smaller than expected.
  To fix this, we can round up the configured width/height passed
  
  to nvdec so that the frames are always at least as large as the
  
  decoder's reported size, and data can be copied out safely.
  In this particular jpeg case, you end up with a blank (green) line
  
  at the bottom due to nvdec refusing to decode the last line, but
  
  the behaviour matches cuviddec, so it's as good as you're going to
  
  get.
  

  • [DH] libavcodec/nvdec.c

• Too large number of skipped frames. FFMPEG, C program

  27 novembre 2017, par gogoer

  I’m writing program on C to capture RTSP stream and write it to files.
  But after some time i get errors :

  Too large number of skipped frames xxxx > 60000

  After this files become incorrect and very small size.
  What the reason of it and how can o fix this problems ?

  a piece of code, where i capture frames and put them to buffer.

          ofmt = av_guess_format( NULL, sFileOutput, NULL );
  
          ofcx = avformat_alloc_context();
  
          ofcx->oformat = ofmt;
  
          int ret2=avio_open( &ofcx->pb, sFileOutput, AVIO_FLAG_WRITE);
  
          if(ret2<0){
  
              fprintf(stderr, "\nError occurred when opening output file: %s\n",av_err2str(ret2));
  
          }
  
  
  
          ost = avformat_new_stream( ofcx, NULL );
  
          avcodec_copy_context( ost->codec, iccx );
  
  
  
          ost->sample_aspect_ratio.num = iccx->sample_aspect_ratio.num;
  
          ost->sample_aspect_ratio.den = iccx->sample_aspect_ratio.den;
  
  
  
          ost->r_frame_rate = ist->r_frame_rate;
  
          ost->avg_frame_rate = ost->r_frame_rate;
  
          ost->time_base = av_inv_q( ost->r_frame_rate );
  
          ost->codec->time_base = ost->time_base;
  
          ost->codec->width = 1280;
  
          ost->codec->height = 800;
  
  
  
          av_init_packet( &pkt );
  
  
  
          while ( av_read_frame( ifcx, &pkt ) >= 0 && start_flag==0 && stop_flag==0){
  
              if ( pkt.stream_index == i_index ) {
  
                  pkt.stream_index = ost->id;
  
                  pkt.pts = av_rescale_q_rnd(pkt.pts, ist->time_base, ost->time_base, AV_ROUND_NEAR_INF|AV_ROUND_PASS_MINMAX);
  
                  pkt.dts = av_rescale_q_rnd(pkt.dts, ist->time_base, ost->time_base, AV_ROUND_NEAR_INF|AV_ROUND_PASS_MINMAX);
  
                  pkt.duration = av_rescale_q(pkt.duration, ist->time_base, ost->time_base);
  
                  pkt.pos = -1;
  
                  av_copy_packet(&pkt_arr[pkg_index],&pkt);
  
              }
  
              av_free_packet( &pkt );
  
              av_init_packet( &pkt );
  
              pkg_index++;
  
  
  
              if(pkg_index>=bufer_size){
  
                  pkg_index=pkg_index-bufer_size;
  
              }
  
          }

• ffmpeg : Error while opening encoder for output stream #0:0 - maybe incorrect parameters such as bit_rate, rate, width or height

  20 novembre 2020, par Alexandre

  I'm experiencing troubles running ffmpeg on my synology. I'm trying to convert .avi video to mp4.

  



  Here is the command :

  



  ffmpeg -i vid20160623.avi -acodec libfaac -b:a 128k -vcodec mpeg4 -b:v 1200k -flags +aic+mv4 -f mp4 vid20160623.mp4

  



  And the logs :

  



  ffmpeg version 2.7.1 Copyright (c) 2000-2015 the FFmpeg developers
  built with gcc 4.9.3 (crosstool-NG 1.20.0) 20150311 (prerelease)
  configuration: --prefix=/usr --incdir='${prefix}/include/ffmpeg' --arch=arm --target-os=linux --cross-prefix=/usr/local/arm-unknown-linux-gnueabi/bin/arm-unknown-linux-gnueabi- --enable-cross-compile --enable-optimizations --enable-pic --enable-gpl --enable-shared --disable-static --enable-version3 --enable-nonfree --enable-libfaac --enable-encoders --enable-pthreads --disable-bzlib --disable-protocol=rtp --disable-muxer=image2 --disable-muxer=image2pipe --disable-swscale-alpha --disable-ffserver --disable-ffplay --disable-devices --disable-bzlib --disable-altivec --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libmp3lame --disable-vaapi --disable-decoder=amrnb --disable-encoder=zmbv --disable-encoder=dca --disable-encoder=ac3 --disable-encoder=ac3_fixed --disable-encoder=eac3 --disable-decoder=dca --disable-decoder=eac3 --disable-decoder=truehd --cc=/usr/local/arm-unknown-linux-gnueabi/bin/arm-unknown-linux-gnueabi-ccache-gcc
  libavutil      54. 27.100 / 54. 27.100
  libavcodec     56. 41.100 / 56. 41.100
  libavformat    56. 36.100 / 56. 36.100
  libavdevice    56.  4.100 / 56.  4.100
  libavfilter     5. 16.101 /  5. 16.101
  libswscale      3.  1.101 /  3.  1.101
  libswresample   1.  2.100 /  1.  2.100
  libpostproc    53.  3.100 / 53.  3.100
Input #0, avi, from 'vid20160623.avi':
  Metadata:
    encoder         : MEncoder git-ab94fc6-4.4.3
  Duration: 00:20:18.07, start: 0.000000, bitrate: 1197 kb/s
    Stream #0:0: Video: mpeg4 (Advanced Simple Profile) (XVID / 0x44495658), yuv420p, 624x352 [SAR 1:1 DAR 39:22], 1056 kb/s, 25 fps, 23.98 tbr, 25 tbn, 23.98 tbc
    Stream #0:1: Audio: mp3 (U[0][0][0] / 0x0055), 48000 Hz, stereo, s16p, 128 kb/s
Output #0, mp4, to vid20160623.mp4':
  Metadata:
    encoder         : MEncoder git-ab94fc6-4.4.3
    Stream #0:0: Video: mpeg4, none, q=2-31, 128 kb/s, SAR 351:352 DAR 0:0, 23.98 fps
    Metadata:
      encoder         : Lavc56.41.100 mpeg4
    Stream #0:1: Audio: aac, 0 channels, 128 kb/s
    Metadata:
      encoder         : Lavc56.41.100 libfaac
Stream mapping:
  Stream #0:0 -> #0:0 (mpeg4 (native) -> mpeg4 (native))
  Stream #0:1 -> #0:1 (mp3 (native) -> aac (libfaac))
Error while opening encoder for output stream #0:0 - maybe incorrect parameters such as bit_rate, rate, width or height


  



  I tried to reduce b:a and b:v but it did not work.

  



  Any help will be welcome.