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• Revision 67483 : debut d’un skel de doc light dediee a un projet

  5 novembre 2012, par cedric@… — Log

  debut d’un skel de doc light dediee a un projet

• libav avformat_open_input fails with signal 11 (Segmentation fault) when opening headerless raw mulaw file

  18 décembre 2019, par jeanPlus

  I tried converting a raw headerless mulaw file with libav. The goal is to create a mp3 file. The ffmpeg command line works fine ..
  ffmpeg -f mulaw -ar 8000 -ac 1 -i raw_ULaw_8000Hz_1CH.raw output.mp3
  So I created a c file and compiled with gcc

      printf("open_input_file-avformat_open_input\n");   
  
      AVCodec* pCodec;
  
      AVCodecContext* pContext;
  
  
  
      avcodec_register_all();
  
  
  
      pCodec = avcodec_find_encoder(AV_CODEC_ID_PCM_MULAW);
  
      if (!pCodec) 
  
      {
  
          av_log(NULL, AV_LOG_ERROR, "Cannot find encoder AV_CODEC_ID_PCM_MULAW\n");
  
          abort();
  
      }
  
  
  
      pContext = avcodec_alloc_context3(pCodec);
  
      if(pContext == NULL) 
  
      {
  
          av_log(NULL, AV_LOG_ERROR, "Cannot allocate context avcodec_alloc_context3(..)\n");
  
          abort();
  
      }
  
  
  
      pContext->channels = 1;    
  
      pContext->bit_rate = 64000;
  
      pContext->sample_fmt = AV_SAMPLE_FMT_S16;//AV_SAMPLE_FMT_U8;
  
      pContext->channel_layout = AV_CH_LAYOUT_MONO;    
  
      pContext->sample_rate=8;
  
  
  
      if(avcodec_open2(&pContext, &pCodec, NULL) < 0) 
  
      {
  
          av_log(NULL, AV_LOG_ERROR, "Cannot open context(..)\n");
  
          abort();
  
      }
  
  
  
      printf("context bitrate:%d\n",pContext->bit_rate);
  
  
  
     AVDictionary *options = NULL;
  
     av_dict_set(&options, "f", "mulaw", 0);// TODO: must find what the mulaw options are 
  
  
  
      if (avformat_open_input(&pContext, "raw_ULaw_8000Hz_1CH.raw", "raw", &options) < 0){rmat_open_input(&pContext, "raw_ULaw_8000Hz_1CH.raw", NULL, NULL) < 0){
  
           av_log(NULL, AV_LOG_ERROR, "Cannot open input file %s , return code: %s \n", filename, av_err2str(ret));
  
          abort();
  
      }

  output after execution

  ./rawtomp3.libav raw_ULaw_8000Hz_1CH.raw  output.mp3
  
  open_input_file-avformat_open_input
  
  context bitrate:64000
  
  signal 11 (Segmentation fault), address is 0x100000010 from 0x7f2f85f17a25
  
  [bt]: (1) /usr/lib/x86_64-linux-gnu/libavformat.so.57(avformat_open_input+0x485) [0x7f2f85f17a25]
  
  [bt]: (2) /usr/lib/x86_64-linux-gnu/libavformat.so.57(avformat_open_input+0x485) [0x7f2f85f17a25]
  
  [bt]: (3) ./rawtomp3.libav(+0x172a) [0x5576ec8f272a]
  
  [bt]: (4) ./rawtomp3.libav(main+0x104) [0x5576ec8f294a]
  
  [bt]: (5) /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xe7) [0x7f2f854e8b97]
  
  [bt]: (6) ./rawtomp3.libav(_start+0x2a) [0x5576ec8f20ea]

  I tried with passing context prefilled and without .. what needs to change ?

• A light-weight Rust crate for encoding videos from images and audios [closed]

  24 décembre 2019, par Agus Putra Dana

  I want to make a web app that enable users to generate video from canvas animation. I’m aware that I can record the canvas animation and the audios using catureStream(), but I want to generate the video without playing the audio. Also, the video frame rate generated using this method is not consistent.

  My idea is to capture the canvas frame by frame and store them as blob to get a consistent frame rate. And then encode the video from these blobs and some audio files uploaded by the user using web assembly. I’m also aware that I can use FFMPEG to encode the video. But the file size of the compiled FFMPEG is quite big.

  Is there any light-weight video encoder library, preferably written in Rust, just for encoding video from images and audios ?