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• Error opening filters : Running ffmpeg through Groovy and ProcessBuilder

  30 octobre 2016, par smeeb

  This question involves the popular Linux media processing utility "ffmpeg", but I think its really a Java 8 ProcessBuilder question at its core. Or possibly an issue w/ Groovy GStrings.

  The ffmpeg command to split an MP4 video into frames/images based on a sampling rate is :

  ffmpeg -i /some/path/to/video.mp4 -vf "select=not(mod(n\,${samplingRate}))" -vsync vfr -q:v 2 img_%d.jpg

  Where ${samplingRate} is a positive integer and represents the number of frames to skip in between creating each frame. So for instance, if you had a video with 430 frames in it, and wanted to sample every 50th frame, your command would be :

  ffmpeg -i /some/path/to/video.mp4 -vf "select=not(mod(n\,50))" -vsync vfr -q:v 2 img_%d.jpg

  Which would then create 8 (or maybe 9, not gonna do the math for a pretend example) JPG files called img_1.jpg, img_2.jpg, ...etc. The first image would be the 50th frame in the video. The second image would be the 100th frame, etc. I have ran the above command directly from a terminal and confirmed that it is correct and succeeds without errors.

  I have a Groovy app, and am trying to run this ffmpeg command via a Java 8 ProcessBuilder, and am having issues with the select= argument. Currently I have :

  int numSamples = 50
  
  Process frameSamplerProc = new ProcessBuilder(
  
      'ffmpeg',
  
      '-i',
  
      "/home/myuser/some/path/to/video.mp4",
  
      '-vf',
  
      "\"select=not(mod(n\\,${numSamples}))\"",
  
      '-vsync',
  
      'vfr',
  
      '-q:v',
  
      '2',
  
      'sample%d.jpg'
  
  ).redirectErrorStream(true).start()
  
  
  
  frameSamplerProc.inputStream.eachLine { fsamplerLine ->
  
      println(fsamplerLine)
  
  }

  When I run thise code, I don’t get any errors, but I do see errors in ffmpeg’s output :

  ffmpeg version N-81995-gd790e48 Copyright (c) 2000-2016 the FFmpeg developers
  
  // Omitting the next ~50 lines of output as it all looks normal
  
  
  
  Metadata:
  
    creation_time   : 2016-10-27T20:20:01.000000Z
  
    handler_name    : SoundHandle
  
  [AVFilterGraph @ 0x3eddc80] No such filter: '"select'
  
  Error opening filters!

  I’m wondering if I’m not escaping the select argument properly or if I’m passing in a bad array to the ProcessBuilder. Can anybody spot where I’m going awry ?

• Moviepy write_videofile works the second time but not the first ?

  30 novembre 2023, par Andrew Best

  I'm concatenating a list of video objects together then writing them with write_videofile, weirdly enough the first time I write the file, it plays fine for the first halfish then the first few frames of each clip in the file afterwards plays before freezing. But here's the odd part, If I write the exact same video object right after the first video writes, it writes just fine and plays perfectly.

  


  Here's my code

  


  from moviepy.editor import VideoFileClip, concatenate_videoclips

clipslist = []
clips = ['https://clips-media-assets2.twitch.tv/AT-cm%7C787619651.mp4', 'https://clips-media-assets2.twitch.tv/AT-cm%7C787628097.mp4', 'https://clips-media-assets2.twitch.tv/2222789345-offset-20860.mp4', 'https://clips-media-assets2.twitch.tv/AT-cm%7C787624765.mp4', 'https://clips-media-assets2.twitch.tv/AT-cm%7C787539697.mp4', 'https://clips-media-assets2.twitch.tv/39235981488-offset-3348.mp4', 'https://clips-media-assets2.twitch.tv/AT-cm%7C788412970.mp4', 'https://clips-media-assets2.twitch.tv/AT-cm%7C787682495.mp4', 'https://clips-media-assets2.twitch.tv/AT-cm%7C787962593.mp4', 'https://clips-media-assets2.twitch.tv/AT-cm%7C787627256.mp4', 'https://clips-media-assets2.twitch.tv/AT-cm%7C787573008.mp4', 'https://clips-media-assets2.twitch.tv/AT-cm%7C788543065.mp4', 'https://clips-media-assets2.twitch.tv/AT-cm%7C787593688.mp4', 'https://clips-media-assets2.twitch.tv/AT-cm%7C788079881.mp4', 'https://clips-media-assets2.twitch.tv/AT-cm%7C788707738.mp4', 'https://clips-media-assets2.twitch.tv/AT-cm%7C788021727.mp4', 'https://clips-media-assets2.twitch.tv/AT-cm%7C787595029.mp4', 'https://clips-media-assets2.twitch.tv/39233367648-offset-9536.mp4', 'https://clips-media-assets2.twitch.tv/AT-cm%7C788517651.mp4', 'https://clips-media-assets2.twitch.tv/AT-cm%7C788087743.mp4', 'https://clips-media-assets2.twitch.tv/AT-cm%7C787497542.mp4', 'https://clips-media-assets2.twitch.tv/39233367648-offset-9154.mp4', 'https://clips-media-assets2.twitch.tv/7109626012888880881-offset-4818.mp4', 'https://clips-media-assets2.twitch.tv/72389234-offset-760.mp4', 'https://clips-media-assets2.twitch.tv/AT-cm%7C787774924.mp4', 'https://clips-media-assets2.twitch.tv/AT-cm%7C787565708.mp4']

for clip in clips:
    dlclip = VideoFileClip(clip, target_resolution=(1080, 1920))  # Download clip
    clipslist.append(dlclip)

videofile = concatenate_videoclips(clipslist)
videofile.write_videofile("final1.mp4") # Broken after the first halfish
videofile.write_videofile("final2.mp4") # Works entirely fine.
videofile.close


  


  Any ideas ? Any suggestions appreciated.

  


  

  • Sometimes when the video is small enough it seems to write the first time just fine too.

  


  • It seems there is no set point where it breaks, each time I write it for the first time it typically breaks at a different spot.

  


  • I've tried waiting for the thread to exit and sleeping after the concatenation and that doesn't seem to fix the issue.

  


  


• 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 !