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• ffprobe using lowercase or uppercase for format tags

  4 novembre 2020, par malat

  I am trying to understand the behavior of ffprobe with regards to using either uppercase or lowercase convention for format tags.

  


  Here are the steps to reproduce. Create an MP4, AVI and a MKV container from an existing MP4 movie :

  


  $ ffmpeg -y -i input.mp4 -c:a copy -c:v copy -metadata title="This is my title" -metadata date="1234" -metadata genre="erneg" output.mp4
$ ffmpeg -y -i input.mp4 -c:a copy -c:v copy -metadata title="This is my title" -metadata date="1234" -metadata genre="erneg" output.avi
$ ffmpeg -y -i input.mp4 -c:a copy -c:v copy -metadata title="This is my title" -metadata date="1234" -metadata genre="erneg" output.mkv


  


  Now using, either

  


  % ffprobe -v error -hide_banner -show_format -print_format json -i output.mp4


  


  or :

  


  % ffprobe -v error -hide_banner -show_format -print_format json -i output.avi


  


  I get respectively :

  


      "tags": {
        "major_brand": "isom",
        "minor_version": "512",
        "compatible_brands": "isomiso2mp41",
        "title": "This is my title",
        "date": "1234",
        "encoder": "Lavf58.20.100",
        "genre": "erneg"
    }


  


  and

  


      "tags": {
        "date": "1234",
        "genre": "erneg",
        "title": "This is my title",
        "encoder": "Lavf58.20.100"
    }


  


  but with MKV container, I get the uppercase convention (except for 'title') :

  


      "tags": {
        "title": "This is my title",
        "DATE": "1234",
        "MAJOR_BRAND": "isom",
        "MINOR_VERSION": "512",
        "COMPATIBLE_BRANDS": "isomiso2mp41",
        "GENRE": "erneg",
        "ENCODER": "Lavf58.20.100"
    }


  


  What is the difference in between the lowercase and uppercase convention for format tags in ffprobe ?

  


  ---

  


  For reference, system is Debian/buster.

  


  % ffmpeg -version 
ffmpeg version 4.1.6-1~deb10u1 Copyright (c) 2000-2020 the FFmpeg developers
built with gcc 8 (Debian 8.3.0-6)
configuration: --prefix=/usr --extra-version='1~deb10u1' --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --arch=amd64 --enable-gpl --disable-stripping --enable-avresample --disable-filter=resample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librsvg --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-lv2 --enable-omx --enable-openal --enable-opengl --enable-sdl2 --enable-libdc1394 --enable-libdrm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libx264 --enable-shared
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
libavresample   4.  0.  0 /  4.  0.  0
libswscale      5.  3.100 /  5.  3.100
libswresample   3.  3.100 /  3.  3.100
libpostproc    55.  3.100 / 55.  3.100


  


• encode YUV420 frame to VP9

  21 novembre 2018, par User800222

  As title,

  I’m pulling frames from a IP camera. I converted the input raw data to YUV420 format, and would like to encode YUV420 to VP9, and save frames as .webm format. Would I be able to do that ? Or should I input a BGR444 format for encoding ?

  BTW, to set up the parameters for encoding vp9. Is the av_dict_set() the right function for setting parameters ?

  Ex : (http://wiki.webmproject.org/ffmpeg/vp9-encoding-guide)

  av_dict_set(&opt, "crf"    , "23", 0);
  
  av_dict_set(&opt, "speed"  , "4" , 0);
  
  av_dict_set(&opt, "threads", "8" , 0);
  
  av_dict_set(&opt, "pass"   , "1" , 0);
  
  av_dict_set(&opt, "b:v", "1400k", 0);

  Edit : The wiki uses 2 pass for setting parameters, would I be able to do in with 1 pass ?

  Edit2 : Blow code seems to be working, wonder how can I bring the size of the videos (vp9) down ? Currently, I have similar size as using h264 encoder.

      av_dict_set(&opt, "crf"    ,        "45", 0);  
  
      av_dict_set(&opt, "speed"  ,        "8" , 0); 
  
      av_dict_set(&opt, "quality",        "realtime", 0);
  
      av_dict_set(&opt, "threads",        "8" , 0);
  
      av_dict_set(&opt, "tile-columns",   "3", 0);
  
      av_dict_set(&opt, "frame-parallel", "1", 0);
  
      av_dict_set(&opt, "row-mt",         "1", 0);

  Update1 :
  YUV420P can be encoded as VP9 !

• ffmpeg invalid argument for vp9 encoding

  17 juin 2015, par user3083672

  I’m following the recommended settings for vp9 encoding here : http://wiki.webmproject.org/ffmpeg/vp9-encoding-guide

  Using this command :

  ffmpeg -i test.mp4 -c:v libvpx-vp9 -pass 1 -b:v 1000K -threads 8 -speed 4 \
  
  -tile-columns 6 -frame-parallel 1 -auto-alt-ref 1 -lag-in-frames 25 \
  
  -an -f webm /dev/null

  produces the following error :

  [NULL @ 0000000005a209c0] Unable to find a suitable output format for '\'
  
  \: Invalid argument

  Any ideas ?