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• Compression of a video with constant background

  28 juin 2017, par Spirou003

  (sorry if my english is bad, I can read it but I don’t write it quite well...)

  I want to compress some videos, which have two particularities :

  • there is a background that covers 90% of the area, during the whole video
  • most of the others elements can be separately described by a picture in move

  My videos are like this one, and don’t have audio. As you can see, almost everything can be described only by using a fixed background, few small images in move, plus a noise. Moreover, this noise will be almost nul and then an entropic coding would be very efficient. I think it will produce tiny files (< 5 Mo) even if the duration is in hours, a result that is very appreciable since I have actually recorded 30h of game (actual size is 3 Go).

  Is there any way to get new video files, that benefit of these informations ? If yes, what are the implication of a such encoding for watching these videos with Windows Media Player, or for usage with ffmpeg ?

  I searched with Google after anything that can help me, but I don’t know which keyword I can use for this, then I didn’t found anything usefull :-(

  Thanks in advance :-)

  PS : another example, the video is accelerated but shows the interesting moves

• FFMPEG set volume in amix

  23 juin 2017, par user5839

  I’ve been trying to mix an audio mp3 with a video mp4 while retaining the mp4 audio. This is working with .

  ffmpeg -y  -i video.mp4 -i audio.mp3
  
   -filter_complex "[0:a][1:a]amix=inputs=2:duration=longest[out]" 
  
   -map 0:v -map [out] output.mp4

  I’m now trying to adjust the volumes of the sound files (video 0.5, audio 1) as part of the mix.

  I’ve been trying things like

  ffmpeg  -i 020c276b-face-4bb3-9169-e8969c1232ba.mp4 -i test.mp3 -filter_complex 
  
   "[0:a]aformat=sample_fmts=fltp:sample_rates=44100:channel_layouts=stereo,volume=0.5[a1]; 
  
    [1:a]aformat=sample_fmts fltp:sample_rates=44100:channel_layouts=stereo,volume=0.8[a2]; 
  
    [a1][a2]amerge,pan=stereo:c0code>

  And I get errors such as

  [Parsed_aformat_2 @ 037f8620] Error parsing sample format : sample_fmts
  fltp. [AVFilterGraph @ 038be620] Error initializing filter ’aformat’
  with args ’sample
  _fmts fltp:sample_rates=44100:channel_layouts=stereo’ Error initializing complex filters. Invalid argument

  Does anyone know how to make the code I’ve code above that is working, also change the volume of the inputs ?

  Thanks

• Android ffmpeg needs android.permission.ACCESS_COARSE_LOCATION for compression

  20 septembre 2018, par htafoya

  I’m using FFmpegAndroid library (based on C) on a project in order to compress encode some videos.

  The library requires the use of android.permission.ACCESS_COARSE_LOCATION permission.

  If I remove it the compression fails, but I get no additional detail on where the lib requires the permission.

  The shell command is :

  [/data/user/0/app_package/files/ffmpeg, -y, -i, /storage/emulated/0/WhatsApp/Media/WhatsApp Video/VIdidi.mp4, -async, 1, -c:v, libx264, -profile:v, high, -preset, ultrafast, -b:v, 1400k, -maxrate, 1400k, -r, 30, -vf, scale=-1:960, /storage/emulated/0/appname/out.mp4]

  Do anyone knows on what this is used ? As I don’t want my users to be asked for a permission without clear understanding on the usage.