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• Re-encode video stream only with ffmpeg (and with all audio streams)

  25 septembre 2016, par razr

  I’m looking for a way to re-encode the video stream of a movie only and keep all other streams as they are using ffmpeg or more specific streamio/streamio-ffmpeg (Github - StreamIO-FFMPEG).

  I already tried various combinations of -map 0 or -map a:0 -map s:0, but in all combinations I tried, either nothing is encoded at all, or not all other streams are copied to the new file. In most cases there is only one audio stream after encoding, when there were two before, and sometimes the subtitle streams are lost, too. Also most times the info what language the streams are in gets lost.

  So when I have a movie file (mkv) with the following streams :

  0: video [H.264, 1080p]
  
  1: audio [english, mp3]
  
  2: audio [french, mp3]
  
  3: subtitle [english (forced)]
  
  4: subtitle [english]

  What should the ffmpeg parameters be, if I want to encode the video file to H.265 and 720p and keep all other streams as they are ?

  What should the parameters be, if I additionally want to encode the audio streams as AAC ?

  Thanks in advance !

• Concatenate audio parts of different videos with ffmpeg [migrated]

  15 août 2024, par Swike

  So I have two videos :

  


  

  • Vid_eng.mkv is a high resolution video that has the audio in English.

  


  • Vid_esp.mkv is a low resolution video that has the audio in Spanish.

  


  


  Both videos are showing more or less the same stuff but the difference is that the Spanish one has the intro and outro cut out (the first 66 seconds are missing).

  


  I want to create a new video file, Vid_out.mkv that has the Vid_eng.mkv video and both audios (so the final file has multistream audio). The issue is that the Spanish audio will not be in sync with the high resolution video, so what I did was this :

  


  ffmpeg -i Vid_eng.mkv
       -f lavfi -t 66 -i anullsrc -i Vid_esp.mkv
       -filter_complex "[1:a][2:a]concat=n=2:v=0:a=1[outa]"
       -map 0 -map "[outa]"
       -metadata:s:a:0 language=eng
       -metadata:s:a:1 language=spa
       -disposition:a:1 default
       -c:v copy Vid_out.mkv


  


  What I'm doing here is essentially creating the new Vid_out.mkv using the video from Vid_eng.mkv, the audio multistream from both Vid_eng.mkv and Vid_esp.mkv, but with the twist that the audio from Vid_esp.mkv is actually beginning 66 seconds later (so that it is synced with the English video). I did this by adding 66 seconds of silence (with -f lavfi -t 66 -i anullsrc) and concatenating that silence with the Spanish audio (with -filter_complex "[1:a][2:a]concat=n=2:v=0:a=1[outa]") before adding this concatenated audio stream to the final file as the secondary audio. Also I included some metadata to know the which audio is which.

  


  Everything good for the moment. But now I wanted to try something more sophisticated : instead of having 66 seconds of silence concatenated to the Spanish audio I want 66 seconds of the English audio (the audio from Vid_eng.mkv), then the audio from Vid_esp.mkv, and finally when the Spanish audio has finished and the video is still going, I want the English audio again. So, instead of silence at the beginning and end of the video when played with the secondary audio stream, what I want is the English audio to play. How can I do that with ffmpeg ?

  


  ---

  


  For reference I've been following ideas from these answers :

  


  

  • How to add audios from different videos into one multistream video

  


  • How to add a few seconds of silence to an audio

  


  


• Evolution #3770 : Logo des articles sur les listes

  4 mai 2017, par cedric -

  on doit normalement éviter d’utiliser image_recadre dans le back-office, car il dépend de la présence de gd2 qui n’est pas garantie (alors que image_reduire ou passe_partout fonctionnent avec n’importe quelle lib graphique).
  Mais on peut tricher avec un passe_partout + utilisation en background ou overflow:hidden