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• FFMPEG - How to setup volume when merging two audio streams

  6 octobre 2014, par N3sh

  I just recently entered the magic and scary world of FFMPEG and, although I found quite a lot of guides online, I need help for my current problem.

  I am merging only audio files and I would like to be able to select their volume.

  Here is my current code for merging 2 files :

  ffmpeg -i test\audio00.mp3 -i test\audio01.mp3 -filter_complex amerge 
  
  -c:a libmp3lame -q:a 0 test\output_overlay.mp3

  I tried the following code, extracted from another answer here on SO (the User was also handling video), but it doesn’t work for me :

  ffmpeg -i test\audio00.mp3 -i test\audio01.mp3 -filter_complex "[0:a]volume=0.9[a1];  
  
  [1:a]volume=0.781250[a2]; [a1][a2]amerge,pan=stereo:c0code>

  I got this error :

  [AVFilterGraph @ 030fa8c0] The following filters could not choose their formats: 
  
  Parsed_amerge_2 Consider inserting the (a)format filter near their input or output.

  Is there a simple way to change the volume for the two streams (even for just the second one, it’s the background music) with FFMPEG ?

  P.S. Also, is it possible to have some sort of ’preview’ before actually rendering the file ?

• How To Specify FFMPEG Input Volume For Multple Input Files

  30 septembre 2014, par gbd

  I have 6 similar/separate audio input files feeding into ffmpeg - no video. I’m mixing the 6 input channels down to a stereo output using amix and that works fine. But now I need to change the volume of each individual input channel before the mix down - or maybe as part of the mix down. I’ve looked at and tried aeval (which seems very slow) in the form

   'aeval=val(0)*volChg1:c=same|val(1)*volChg2:c=same|val(2)*volChg3:c=same|val(3)*volChg4:c=same|val(4)*volChg5:c=same|val(5)*volChg6:c=same'

  but that only seems to change the volume of the first channel.

  So the whole input part of my ffmpeg expression looks something like this right now :

  -i inFilePath1 -i inFilePath2 -i inFilePath3 -i inFilePath4 -i inFilePath5 -i inFilePath6 
  
  -filter_complex 'aeval=val(0)*$volChg1:c=same|val(1)*$volChg2:c=same|val(2)*$volChg3:c=same|val(3)*$volChg4:c=same|val(4)*$volChg5:c=same|val(5)*$volChg6:c=same','amix=inputs=6:duration=longest'

  $volChg1-6 are php variables containing the individual volume multipliers - 0.5 for example should halve the volume of that individual channel while 1.0 would leave it unaffected. How do I do this ?

• Revision bc1b3d8412 : Allow DC/H/V/TM on screen content. 6.3% better compression less than 1% compres

  25 octobre 2014, par Alex Converse

  Changed Paths :
   Modify /vp9/encoder/vp9_pickmode.c

  
   Modify /vp9/encoder/vp9_speed_features.c

  
  
  Allow DC/H/V/TM on screen content.

  6.3% better compression
  less than 1% compression time increase

  Change-Id : Ie83c059436e54c09de9e7c87e06e0a6d40dc38fe