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• FFMPEG merge two files cause the video to freeze at the end of the first part

  17 janvier 2015, par Anas

  I am using FFMPEG to cut and merge video file, these are my commands :
  //split the video to three parts

  ffmpeg -i "input.mkv" -ss 00:00:00 -to 00:04:00 -c copy -map 0 -y out0.mkv
  
  ffmpeg -i "input.mkv" -ss 00:05:00 -to 00:22:00 -c copy -map 0 -y out1.mkv
  
  ffmpeg -i "input.mkv" -ss 00:23:00  -c copy -map 0 -y out2.mkv

  //merge these parts in one video again

  ffmpeg  -f concat -i mylist.txt -c copy  -y output.mkv

  //mylist.txt contains :

  file out0.mkv
  file out1.mkv
  file out2.mkv

  And everything works fine, except that the new merged video freeze for 5 seconds at the end of the first merged part, in the above example at sec 04:00 the screen pauses for 5 seconds and then the video continue.

  Do you know why this is happening ? is there a work around please help.

• Can any part of an ffmpeg command use expressions ?

  6 avril 2022, par corgrath

  I am still learning how expressions work with ffmpeg, whether any part of a command can be using expression or not.

  


  As an example, I have this command :

  


  ffmpeg -y -i input.mp3 -af "sofalizer=sofa=ClubFritz1.sofa:type=freq:radius=2:speakers='FL 45|FR 45|BL 45|BR 45'" output.mp3

  


  (The file CubFritz1.sofa can by the way be downloaded here)

  


  Which basically applies the sofalizer effect and specify that each channel should be heard / come from, the left side (45 degrees) of the audio.

  


  This works as expected.

  


  However, I cannot seem to get expressions working in the command at all.

  


  For example this :

  


  ffmpeg -y -i input.mp3 -af "sofalizer=sofa=ClubFritz1.sofa:type=freq:radius=2:speakers='FL if(0, 45, 45)'|'FR if(0, 45, 45)'|'BL if(0, 45, 45)'|'BR if(0, 45, 45)'" output.mp3

  


  Which does an if(0, 45, 45) as a test, so regardless the outcome should be 45, right ?

  


  However, when I run this command, it does not seem to work anymore, meaning the sound is not purely coming from the left side.

  


  I have even tried changing the location of the single ' in the command without luck :

  


  ffmpeg -y -i input.mp3 -af "sofalizer=sofa=ClubFritz1.sofa:type=freq:radius=2:speakers=FL 'if(0, 45, 45)'|FR 'if(0, 45, 45)'|BL 'if(0, 45, 45)'|BR 'if(0, 45, 45)'" output.mp3

  


  My question is, what are the rules for getting expressions working in an ffmpeg command ?

  


  How would the command be rewritten so that the if(0, 45, 45) works ?

  


• Changed : Adding chapters using an array of chapter parts now adds the part counter to the filename before the extension.

  6 juin 2012, par Grandt

  Changed : Adding chapters using an array of chapter parts now adds the part counter to the filename before the extension.