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• ffmpeg - MXF with 4-channel audio : how to create proxies (high quality / small file size) and preserve the audio mapping

  8 juillet 2018, par WhatsYourFunction

  We’ve got MXF sources (h.264 video at UHD (3840x2160) with 4-channels of (4 - PCM S24 mono sources)
  We want Proxies — smallest file size at highest picture quality
  The compression applied to the video and audio essences can be anything,
  And the wrapper can be either MXF or QuickTime
  but we need to preserve the audio mapping (i.e. the Proxy must be 4-channel audio)

  How to do that with ffmpeg ?

  • EDIT Adding ffprobe :

  Metadata :

  uid : ***

  generation_uid : ***

  company_name : CANON

  product_name : EOS C300 Mark II

  product_version : 1.00

  product_uid : ***

  modification_date : 2018-06-28T08:29:24.000000Z

  material_package_umid : ***

  timecode : 02:50:31:17

  Duration : 00:06:35.40, start : 0.000000, bitrate : 395842 kb/s

  Stream #0:0 : Video : h264 (High 4:2:2 Intra), yuv422p10le(tv, progressive), 3840x2160, SAR 1:1 DAR 16:9, 23.98 fps, 23.98 tbr, 23.98 tbn, 47.95 tbc

  Metadata :

   file_package_umid: ***

  Stream #0:1 : Audio : pcm_s24le, 48000 Hz, 1 channels, s32 (24 bit), 1152 kb/s

  Metadata :

   file_package_umid: ***

  Stream #0:2 : Audio : pcm_s24le, 48000 Hz, 1 channels, s32 (24 bit), 1152 kb/s

  Metadata :

   file_package_umid: ***

  Stream #0:3 : Audio : pcm_s24le, 48000 Hz, 1 channels, s32 (24 bit), 1152 kb/s

  Metadata :

   file_package_umid: ***

  Stream #0:4 : Audio : pcm_s24le, 48000 Hz, 1 channels, s32 (24 bit), 1152 kb/s

  Metadata :

   file_package_umid: ***

• Spaces in variable

  13 avril 2012, par Roger

  I am facing some problems with spaces in variables :

  ALBUM=' -metadata album="Peregrinações Alheias"'

  This command :

  ffmpeg -i $R_IMG -r 1 -b 1800 -i $SOUND -acodec libmp3lame -ab 128k "$ALBUM" -y $OUT

  Returns :

  Unable to find a suitable output format for ' -metadata album="Peregrinações Alheias"'

  And if I take out the "" from the variable :

  ffmpeg -i $R_IMG -r 1 -b 1800 -i $SOUND -acodec libmp3lame -ab 128k $ALBUM -y $OUT

  Returns :

  Unable to find a suitable output format for 'Alheias"'

  And I am sure I am missing something in the bash sintax...

  ---

  UPDATE :

  So it looks that the matter is not with spaces but with the "-metadata" argument...

  The problem is that I have many metadata and I'd like to put them in just one variable. Like this :

  META=' -metadata album="Peregrinações" -metadata title="Passeio ao PETAR" -metadata author="Rogério Madureira" -metadata date="2012" -metadata description="Áudio de um passeio ao PETAR" -metadata comment="Áudio capturado com TACAM DR-07MKII e Foto capturada com Canon PowerShot S5IS" '

  And then :

  ffmpeg -i $R_IMG -r 1 -b 1800 -i $SOUND -acodec libmp3lame -ab 128k $META -y $OUT

• Evaluate function within ffmpeg drawtext

  22 juin 2022, par Dan Steingart

  I am looking to display a counter that is a multiple of the frame number on a video created with ffmpeg. Previous answers on SO taught me that a command of the form

  


  ffmpeg -y -r 25  -pattern_type glob -i '*.jpg' -vf "text='%{n}': start_number=0: x=0: y=0: fontcolor=black: fontsize=30: box=1: boxcolor=white: boxborderw=5" -c:a copy movie.mp4


  


  Will display the frame number, and this works nicely. But if I try to evaluate an expression within the %{}, e.g.

  


  ffmpeg -y -r 25  -pattern_type glob -i '*.jpg' -vf "text='%{n*50}': start_number=0: x=0: y=0: fontcolor=black: fontsize=30: box=1: boxcolor=white: boxborderw=5" -c:a copy movie.mp4


  


  Then I get the following error

  


  [Parsed_drawtext_0 @ 0x55683f9b00] %{n*50} is not known    


  


  on each frame. What is the proper syntax to evaluate n*50 and display in drawtext ? TIA.