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• ffmpeg fails with "More than 1k frames duplicated" when merging with xfade

  1 May 2021, by PadawanQ

  When I try to merge 8 or more video clips with the same codec (generated by ffmpeg in a previous step), I get a More than 1000 frames duplicated warning and the resulting output is not merged correctly. This doesn't happen with 7 video clips.

  


  I tried removing the 8th clip to check if there is a problem with that clip, but it happens the same. Also reordering the clips with no success.

  


  The command I use is:

  


  ffmpeg -i scenes/step-000.mp4 -i scenes/step-001.mp4 -i scenes/step-002.mp4 -i scenes/step-003.mp4 -i scenes/step-004.mp4 -i scenes/step-005.mp4 -i scenes/step-008.mp4 -i scenes/step-009.mp4 -filter_complex_script temp/2021-03-17-14-51-13-6.txt  -y -map "[video]" -map "[audio]" -pix_fmt yuv420p -movflags +faststart output.mp4


  


  The content of the filter_complex_script is:

  


  [0][1] xfade=transition=fade:duration=2:offset=2.48 [vtmp1]; [vtmp1][2] xfade=transition=fade:duration=2:offset=12.56 [vtmp2]; [vtmp2][3] xfade=transition=fade:duration=2:offset=100.58 [vtmp3]; [vtmp3][4] xfade=transition=fade:duration=2:offset=167.60 [vtmp4]; [vtmp4][5] xfade=transition=fade:duration=2:offset=222.62 [vtmp5]; [vtmp5][6] xfade=transition=fade:duration=2:offset=232.70 [vtmp6]; [vtmp6][7] xfade=transition=fade:duration=2:offset=282.72 [video]; [0:a][1:a] acrossfade=d=2:c1=tri:c2=tri [atmp1]; [atmp1][2:a] acrossfade=d=2:c1=tri:c2=tri [atmp2]; [atmp2][3:a] acrossfade=d=2:c1=tri:c2=tri [atmp3]; [atmp3][4:a] acrossfade=d=2:c1=tri:c2=tri [atmp4]; [atmp4][5:a] acrossfade=d=2:c1=tri:c2=tri [atmp5]; [atmp5][6:a] acrossfade=d=2:c1=tri:c2=tri [atmp6]; [atmp6][7:a] acrossfade=d=2:c1=tri:c2=tri [audio]


  


  FFMPEG version 4.3.2-tessus

  


• C++ ffmpeg mp4 to mp3 transcoding

  2 July 2014, by Unknown

  I am working on an application that converts the audio of mp4 video to mp3 files. I managed to compile ffmpeg with libmp3lame.

  This is what I have so far

  // Step 1 - Register all formats and codecs
  
  avcodec_register_all();
  
  av_register_all();
  
  
  
  AVFormatContext* fmtCtx = avformat_alloc_context();
  
  
  
  // Step 2 - Open input file, and allocate format context
  
  if(avformat_open_input(&fmtCtx, filePath.toLocal8Bit().data(), NULL, NULL) < 0)
  
      qDebug() << "Error while opening " << filePath;
  
  
  
  // Step 3 - Retrieve stream information
  
  if(avformat_find_stream_info(fmtCtx, NULL) < 0)
  
      qDebug() << "Error while finding stream info";
  
  
  
  // Step 4 - Find the audiostream
  
  int audioStreamIdx = -1;
  
  for(uint i=0; inb_streams; i++) {
  
      if(fmtCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_AUDIO) {
  
          audioStreamIdx = i;
  
          break;
  
      }
  
  }
  
  
  
  if(audioStreamIdx != -1) {
  
      AVCodecContext *audioDecCtx = fmtCtx->streams[audioStreamIdx]->codec;
  
  
  
      // Step 5
  
      AVCodec *aCodec = avcodec_find_decoder(audioDecCtx->codec_id);
  
      avcodec_open2(audioDecCtx, aCodec, NULL);
  
  
  
      // Step 6
  
      AVOutputFormat* outputFormat = av_guess_format(NULL, outPath.toLocal8Bit().data(), NULL);
  
  
  
      // Step 7
  
      AVFormatContext *outformatCtx = avformat_alloc_context();
  
  
  
      // Step 8
  
      AVCodec *encoder = avcodec_find_encoder(AV_CODEC_ID_MP3);
  
      //encoder->sample_fmts = AV_SAMPLE_FMT_S16;
  
      AVCodecContext *audioEncCtx = avcodec_alloc_context3(encoder);
  
      audioEncCtx->sample_fmt = AV_SAMPLE_FMT_S16P;
  
      audioEncCtx->sample_rate = 44100;
  
      audioEncCtx->channel_layout = av_get_default_channel_layout(audioDecCtx->channels);
  
  
  
      avcodec_open2(audioEncCtx, encoder, NULL);
  
  
  
      // Step 9
  
      AVFrame *frame = av_frame_alloc();
  
  
  
      AVPacket pkt;
  
      av_init_packet(&pkt);
  
  
  
      // Step 10
  
      while(av_read_frame(fmtCtx, &pkt) == 0) {
  
          int got_frame = 0;
  
  
  
          if(pkt.stream_index == audioStreamIdx) {
  
              int len = avcodec_decode_audio4(audioDecCtx, frame, &got_frame, &pkt);
  
  
  
              if(got_frame) {
  
                  // Step 11
  
                  AVPacket outPkt;
  
                  av_init_packet(&outPkt);
  
  
  
                  int got_packet = 0;
  
  
  
                  qDebug() << "This is printed";
  
  
  
                  int error = avcodec_encode_audio2(audioEncCtx, &outPkt, frame, &got_packet);
  
  
  
                  qDebug() << "This is not printed...";
  
             }
  
          }
  
      }
  
  
  
      av_free_packet(&pkt);
  
  }
  
  
  
  avformat_close_input(&fmtCtx);

  It goes wrong at the line avcodec_encode_audio2(). It seems like the function does not return. As you can see, the line after the encoding line is not printed. What am I doing wrong?

  Thanks in advance!

• How to compile avconv with libx264 on Ubuntu 12.04 LTS (Precise Pangolin)?

  1 January 2015, by Kugutsumen

  Is there a step-by-step guide on how to compile avconv in Ubuntu?

  It seems hard to search for any tutorial with avconv compared to ffmpeg.