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• FFMPEG — Error when trying to concat multiple files with and without audio

  7 août 2020, par Philban

  Ok so thanks to a fellow user I have the following FFMPEG command that concats 4 videos together. Now if I use this command with 4 video files that all have audio everything works ! However, if 1 or more of the videos do not have sound I get a "matches no streams" error.

  


  Can someone spot whats wrong here please ?

  


  Video Input 1 - No Audio so adding the anullsrc
Video 2 - Has Audio
Video 3 - No Audio
Video 4 - Has Audio

  


  ffmpeg -i noSound1.mp4 -i story1.mp4 -i noSound2.mp4 -i story2.mp4 -t 0.1 -f lavfi -i anullsrc=channel_layout=stereo -filter_complex 
"[0:v]scale=1280:720:force_original_aspect_ratio=decrease,pad=1280:720:(ow-iw)/2:(oh-ih)/2,setsar=1,fps=30,format=yuv420p[v0]; 
 [1:v]scale=1280:720:force_original_aspect_ratio=decrease,pad=1280:720:(ow-iw)/2:(oh-ih)/2,setsar=1,fps=30,format=yuv420p[v1]; 
 [2:v]scale=1280:720:force_original_aspect_ratio=decrease,pad=1280:720:(ow-iw)/2:(oh-ih)/2,setsar=1,fps=30,format=yuv420p[v2]; 
 [3:v]scale=1280:720:force_original_aspect_ratio=decrease,pad=1280:720:(ow-iw)/2:(oh-ih)/2,setsar=1,fps=30,format=yuv420p[v3]; 
 [0:a]aformat=sample_rates=48000:channel_layouts=stereo[a0]; 
 [1:a]aformat=sample_rates=48000:channel_layouts=stereo[a1]; 
 [2:a]aformat=sample_rates=48000:channel_layouts=stereo[a2]; 
 [3:a]aformat=sample_rates=48000:channel_layouts=stereo[a3]; 
 [v0][a0][v1][a1][v2][a2][v3][a3]concat=n=4:v=1:a=1[v][a]" 
-map "[v]" -map "[a]" -c:v libx264 -c:a aac -movflags +faststart testOutput.mp4


  


  Here is the error :

  


  Stream specifier ':a' in filtergraph description [0:v]scale=1280:720:force_original_aspect_ratio=decrease,pad=1280:720:(ow-iw)/2:(oh-ih)/2,setsar=1,fps=30,format=yuv420p[v0];  [1:v]scale=1280:720:force_original_aspect_ratio=decrease,pad=1280:720:(ow-iw)/2:(oh-ih)/2,setsar=1,fps=30,format=yuv420p[v1];  [2:v]scale=1280:720:force_original_aspect_ratio=decrease,pad=1280:720:(ow-iw)/2:(oh-ih)/2,setsar=1,fps=30,format=yuv420p[v2];  [3:v]scale=1280:720:force_original_aspect_ratio=decrease,pad=1280:720:(ow-iw)/2:(oh-ih)/2,setsar=1,fps=30,format=yuv420p[v3];  [0:a]aformat=sample_rates=48000:channel_layouts=stereo[a0];  [1:a]aformat=sample_rates=48000:channel_layouts=stereo[a1];  [2:a]aformat=sample_rates=48000:channel_layouts=stereo[a2];  [3:a]aformat=sample_rates=48000:channel_layouts=stereo[a3];  [v0][a0][v1][a1][v2][a2][v3][a3]concat=n=4:v=1:a=1[v][a] matches no streams.


  


  Now a slightly separate question. If I have N input videos where i do not know if they have sound or not, is there a way I can have a loop that does the above without having massive amounts of command lines ?
Many thanks !

  


• FFMPEG xstack not recognizing inputs

  12 août 2020, par Josh

  I'm trying to arrange three input videos into a single output video using ffmpeg's xstack. I currently have the operations working with a vstack followed by an hstack, but would like to combine them into an xstack for performance.

  


  I've tried copying the syntax from multiple locations such as :

  


  https://trac.ffmpeg.org/wiki/Create%20a%20mosaic%20out%20of%20several%20input%20videos%20using%20xstack

  


  Vertically or horizontally stack (mosaic) several videos using ffmpeg ?

  


  My command is as follows :

  


  


  C :\ffmpeg\bin\ffmpeg.exe -i states_full.mp4 -i title.mp4 -i graphs.mp4" -filter_complex "[0:v] setpts=PTS-STARTPTS, scale=qvga [a0] ; [1:v] setpts=PTS-STARTPTS, scale=qvga [a1] ; [2:v] setpts=PTS-STARTPTS, scale=qvga [a2] ; [a0][a1][a2]xstack=inputs=3:layout=0_0|w0_0|w0_h0[out] " -map "[out]" -c:v libx264 -t '30' -f matroska output.mp4

  


  


  The command always errors out at the same spot, with the same error message :

  


  


  'w0_0' is not recognized as an internal or external command,
operable program or batch file.

  


  


  Some odd behavior is that even when I change the layout section to :

  


  layout=w0_0|0_0|w0_h0


  


  The error message is still on the middle '0_0' meaning it may be an error in formatting.

  


  This issue is very strange, as the vstack and hstack still work, only the xstack fails.

  


• Evolution #4551 (Nouveau) : Filtre couleur_saturation plus strict

  16 septembre 2020

  Le filtre couleur_saturation ne fait pas exactement ce que son nom suggère : l’algorithme utilisé ne modifie pas que la saturation, mais également la luminosité.
  Par exemple en baissant la saturation à zéro, on s’attendrait à obtenir une nuance de gris, et pas du blanc pur.

  Ci-dessous l’image hotlinkée de l’article de spip.net pour référence :
  

  Je propose d’ajouter un param au filtre pour permettre d’activer un fonctionnement plus strict, qui ne changerait que la saturation et rien d’autre.
  Avec le param mis à true, fonctionnement très simple : on tire le hsl depuis l’exadécimal, dedans on ne change que le composant ’s’ avec la valeur demandée, et on repasse en hexadécimal.

  Nb : ça demanderait aussi d’ajouter le param dans le filtre de Spip