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• avformat/img2dec : probe JFIF/Exif header

  25 novembre 2021, par Alex Xu (Hello71)

  avformat/img2dec : probe JFIF/Exif header
  Due to reasons, mpv doesn't pass filename when probing. mpv also sets
  
  default probescore threshold to 26. Since the current jpeg_probe
  
  implementation returns 25 until EOI, it means that the whole image needs
  
  to be probed to succeed. Worse, the whole image is not passed at once ;
  
  increasingly large buffers are tried before that. Adding it up together,
  
  if many demuxers are enabled, moderately large JPEG files (few MB) can
  
  take several seconds to open, despite taking less than 1 second to
  
  actually decode.
  Therefore, adjust the heuristic to be more optimistic if proper JFIF or
  
  Exif segments are found. While not strictly required, the vast majority
  
  of JPEG-ish files have one or the other or both.
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavformat/img2dec.c

• Where can discord bots find the ffmpeg buildpack heroku

  11 août 2020, par Isiah

  I'm making a bot which outputs a mp3 file to the voice chat with discord.py, It works localy by using :

  


  vc.play(discord.FFmpegPCMAudio(executable="ffmpeg/bin/ffmpeg.exe", source=noise.mp3))

  


  However I'm now hosting it on Heroku, i have the buildpack installed but how can my code access it in replacement of the code above

  


• Find better VP8 parameters for robustness in UDP streaming with libav/ffmpeg

  24 octobre 2014, par lmNt

  I’m facing some problems in my video chat application, which is using libav libraries. I am sending 1080p videos encoded in VP8 as WebM container via UDP and it works quite well. Most of the time, the decoder on either side recovers from packet losses due to the transmission.

  However at some point in time it just freezes and never recovers again. This happens on both sides eventually. I was searching for VP8 codec parameters to set for increased robustness, when sending over lossy transmission channels. And I combined some of which I found, in order to increase robustness. However, it still freezes after some time of video chat.

  Here are the parameters I am currently using.

    pVidCodecCtx->codec_id     = AV_CODEC_ID_VP8;
  
    pVidCodecCtx->codec_type   = AVMEDIA_TYPE_VIDEO;
  
    pVidCodecCtx->width        = frmQ->pCodecCtx->width; //1920
  
    pVidCodecCtx->height       = frmQ->pCodecCtx->height; //1080
  
    pVidCodecCtx->time_base    = frmQ->pCodecCtx->time_base;
  
    pVidCodecCtx->pix_fmt      = PIX_FMT_YUV420P;
  
    pVidCodecCtx->qmin         = 4;
  
    pVidCodecCtx->qmax         = 56;
  
    pVidCodecCtx->bit_rate     = pVidCodecCtx->width * pVidCodecCtx->height * 6;
  
    pVidCodecCtx->slices       = 8;
  
    pVidCodecCtx->profile      = 3;
  
    pVidCodecCtx->thread_count = 3;
  
    pVidCodecCtx->keyint_min   = 5;
  
    av_dict_set(&pDictCodecOpts, "rc_lookahead", "0", 0);
  
    av_dict_set(&pDictCodecOpts, "quality", "realtime", 0);
  
    av_dict_set(&pDictCodecOpts, "deadline", "realtime", 0);
  
    av_dict_set(&pDictCodecOpts, "max-intra-rate", "0", 0);
  
    av_dict_set(&pDictCodecOpts, "qcomp", "0", 0);
  
    av_dict_set(&pDictCodecOpts, "default", "er", 0);
  
    av_dict_set(&pDictCodecOpts, "error_resilient", "er", 0);
  
    av_dict_set(&pDictCodecOpts, "partitions", "er", 0);

  Most of the parameters I extracted from the ffmpeg code for the vpx encoder.

  Do I also have to set parameters for the decoder in order to increase error resilience ?
  Or am I missing some parameters in the encoder or setting them incorrectly. Any help or hints are greatly appreciated.