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• ffmpeg bitrate won't change despite argument [duplicate]

  5 février 2019, par Dillon Wright

  This question already has an answer here :

  • Wav audio file compression not working
    
    2 answers
    

  I am attempting to change the codec a wav file is encoded in to do this i am using ffmpeg however when i do this conversion it sets the bit-rate to 128k and i cannot set it lower then this

  i have already tried to set the bit-rate using the b:a 8k argument however it does not change the output bit rate i have then tried to modify the sample and it does change this change also affects the bit rate.

  I have also tried changing the audio codec this has resulted in a lower bit-rate as well it also makes me suspect some codecs may have a minimum bit rate at least they have different default bit rates.

  C :/ffmpeg.exe -i "input.wav" -ar 8000 -b:a 8000 -c pcm_u8 "output.wav"

  here is the output debugging i get

  ffmpeg version 4.1 Copyright (c) 2000-2018 the FFmpeg developers
  built with gcc 8.2.1 (GCC) 20181017
  libavutil 56. 22.100 / 56. 22.100
  libavcodec 58. 35.100 / 58. 35.100
  libavformat 58. 20.100 / 58. 20.100
  libavdevice 58. 5.100 / 58. 5.100
  libavfilter 7. 40.101 / 7. 40.101
  libswscale 5. 3.100 / 5. 3.100
  libswresample 3. 3.100 / 3. 3.100
  libpostproc 55. 3.100 / 55. 3.100
  Guessed Channel Layout for Input Stream #0.0 : mono
  Input #0, wav, from ’input.wav’ :
  Duration : 00:21:03.08, bitrate : 8 kb/s
  Stream #0:0 : Audio : g729 ([131][0][0][0] / 0x0083), 8000 Hz, mono, s16, 8 kb/s
  Stream mapping : Stream #0:0 -> #0:0 (g729 (native) -> pcm_u8 (native))
  Output #0, wav, to ’output.wav’ :
  Metadata :
  ISFT : Lavf58.20.100
  Stream #0:0 : Audio : pcm_u8 ([1][0][0][0] / 0x0001), 8000 Hz, mono, u8, 64 kb/s
  Metadata :
  encoder : Lavc58.35.100 pcm_u8
  size= 2304kB time=00:05:10.59 bitrate= 60.8kbits/s speed= 621x
  size= 4864kB time=00:10:38.10 bitrate= 62.4kbits/s speed= 638x
  size= 7680kB time=00:16:23.05 bitrate= 64.0kbits/s speed= 637x
  size= 9868kB time=00:21:03.08 bitrate= 64.0kbits/s speed= 630x
  video:0kB audio:9868kB subtitle:0kB other streams:0kB global headers:0kB >muxing overhead : 0.000772

• Capture camera + mic and encode to h264/aac on macOS

  16 décembre 2018, par Flock Dawson

  I’m having trouble capturing and encoding audio+video on-the-fly on macOS.

  I tried two options :

  1. ffmpeg

     ffmpeg -threads 0 -f avfoundation -s 1920x1080 -framerate 25 -I 0:0 -async 441 -c:v libx264 -preset medium -pix_fmt yuv420p -crf 22 -c:a libfdk_aac -aq 95 -y

  2. gstreamer

     gst-launch-1.0 -ve avfvideosrc device-index=0 ! video/x-raw,width=1920,height=1080,framerate=25/1 ! vtenc_h264 ! queue ! mp4mux name=mux ! filesink location=out.mp4  osxaudiosrc device=0 ! audio/x-raw ! faac midside=false ! queue ! mux.

  The ffmpeg option works, but only for lower resolutions. With higher resolutions, the Mac mini (2018 gen) can’t do the heavy lifting. I think because I installed ffmpeg with brew, so it wasn’t compiled on my machine, meaning it doesn’t use the h264 hardware encoder in the Mac ?

  The gstreamer option works as well, but there’s a slight audio/video sync issue (audio is 100ms ahead of the video). I can’t seem to add delay to the GStreamer queue (it ignores it) :

  queue max-size-buffers=0 max-size-time=0 max-size-bytes=0 min-threshold-time=100000000

  Anyone who has any experience with this ? Thanks !

• ffmpeg avcodec_open2() return error -22 only in ubuntu

  26 octobre 2020, par User800222

  AS title,

  


  I'm working on a project on Mac with ffmpeg. It runs on my Mac to encode frames to vp9 & vp8. But when I run it on my docker image in a ubuntu, the function avcodec_open2(), returns -22 error. (only for vp9&vp8, h264 works).

  


  I wonder if the error comes from the setting parameters part ? But it's still weird to have it working on mac but not in ubuntu.

  


  Does anyone has a similar experience ?

  


  bool open_video(AVFormatContext * oc,AVCodec * codec,OutputStream * ost,AVDictionary * opt_arg, bool reduceQuality) {
    int ret;
    AVCodecContext * c = ost->st->codec;
    AVDictionary * opt = NULL;
    av_dict_copy(&opt,opt_arg,0);

    if(codec264){
      // http://arstechnica.com/civis/viewtopic.php?f=6&t=1239375
      av_dict_set(&opt,"refs",    "3",          0);
      av_dict_set(&opt,"vprofile","main",       0);  // 2 versions to support differents libav/ffmpeg
      av_dict_set(&opt,"profile", "main",       0);
      
      //av_dict_set(&opt,"preset","superfast",0);
      //av_dict_set(&opt,"preset","ultrafast",0);
      av_dict_set(&opt,"preset","superfast",0);
      //av_dict_set(&opt,"preset","slow",0);
      
      //https://mattgadient.com/2013/06/12/a-best-settings-guide-for-handbrake-0-9-9/
      //av_dict_set(&opt, "tune", "zerolatency", 0); //bluerry but very small size
      //av_dict_set(&opt, "tune", "fastdecode", 0); // hd but large size
      // 23 300k, 29 150k, 35 75k
      if(reduceQuality)
        av_dict_set(&opt, "crf", "35", 0); //35 +-6 decrease/increase bitrate half/twice
      else
        av_dict_set(&opt, "crf", "29", 0); //29 +-6 decrease/increase bitrate half/twice
    
    }
    else if (codecVP9)
    { 
        // Setting explanation:
        // http://wiki.webmproject.org/ffmpeg/vp9-encoding-guide
        // https://developers.google.com/media/vp9/live-encoding/
        // https://developers.google.com/media/vp9/settings/vod/
        // https://developers.google.com/media/vp9/bitrate-modes/

        if(reduceQuality) //crf is the quality value for VP9 (0-63), lower the better quality youll get 
          av_dict_set(&opt, "crf"    ,      "40",         0); 
        else
          av_dict_set(&opt, "crf"    ,      "45",         0);
        av_dict_set(&opt, "speed"  ,        "8" ,         0);
        av_dict_set(&opt, "quality",        "realtime",   0); //realtime is recommended
        //av_dict_set(&opt, "threads",        "4" ,         0);
        //av_dict_set(&opt, "tile-columns",   "2",          0);
        //av_dict_set(&opt, "frame-parallel", "1",          0);
        //av_dict_set(&opt, "row-mt",         "1",          0);
        av_dict_set(&opt, "b:v",            "1",         0);
        av_dict_set(&opt, "g",              "400",        0); //key frame interval (big difference in vid size)

        //av_dict_set(&opt, "maxrate",        "3k",         0);
        //av_dict_set(&opt, "minrate",        "1k",         0);
        //av_dict_set(&opt, "hwaccel",        "vaapi",      0);
        //av_dict_set(&opt, "c:v",            "libvpx-vp9", 0);
        
    }
    else if (codecVP8)
    {
        // https://trac.ffmpeg.org/wiki/Encode/VP8 
        av_dict_set(&opt, "passes"    ,        "1" ,         0);   
        av_dict_set(&opt, "cpu-used"  ,        "15" ,         0); 
        av_dict_set(&opt, "qmax"      ,        "63",         0);   
        av_dict_set(&opt, "rt"        ,          "",         0); // realtime setting
        //av_dict_set(&opt, "crf"       ,        "10",         0);   

        if(reduceQuality)
          av_dict_set(&opt, "qmin"     ,        "40",        0); // Lower quality, smaller sizes
        else
          av_dict_set(&opt, "qmin"     ,        "35",        0); // Higher quality, larger sizes
    }
    else 
    {
        if(reduceQuality)
            av_dict_set(&opt, "x265-params", "crf=29", 0);
        else
            av_dict_set(&opt, "x265-params", "crf=23", 0);
        
        av_dict_set(&opt, "preset", "ultrafast", 0);
        av_dict_set(&opt, "tune", "zerolatency", 0);
//        av_dict_set(&opt, "profile", "main", 0);
    }
      
    // Open the codec
    ret = avcodec_open2(c,codec,&opt);
    av_dict_free(&opt);
    if (ret < 0) {
        cout << "Could not open video codec. (error code:" << ret << ")\n";
        return false;
    } // if


  


  Edit : Does anyone know if the ffmpeg-linux using different parameters' name for setting from other platform's (like Mac) ?

  


  Eidt2 : It seems like even if I don't set any options parameters, it's still giving me -22 error. Ex : ret = avcodec_open2(c, codec, NULL)