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• From Python, piping images to FFMPEG process with audio input, "-shortest" flag causes output file to contain only 1 frame of video and entire audio

  7 novembre 2023, par b_yang

  From Python, I run FFMPEG and write images to its stdin via pipe, the FFMPEG process has an audio file as input too. Everything works fine like this :

  


  cmd = ['ffmpeg', '-hide_banner', '-y', '-loglevel', 'error', '-f', 'rawvideo', 
'-pix_fmt', 'bgr24', '-video_size', '720x1280', '-r', '30.0', '-an', '-i', '-',
'-i', 'audio.aac', '-acodec', 'copy', 
'-crf', '14', '-pix_fmt', 'yuv420p', 'output.mp4']
proc = subprocess.Popen(cmd, **popen_params)


  


  Because the audio duration might be longer than the video duration, I added a '-shortest' flag (before '-crf') :

  


  cmd = ['ffmpeg', '-hide_banner', '-y', '-loglevel', 'error', '-f', 'rawvideo', 
'-pix_fmt', 'bgr24', '-video_size', '720x1280', '-r', '30.0', '-an', '-i', '-',
'-i', 'audio.aac', '-acodec', 'copy', 
'-shortest', '-crf', '14', '-pix_fmt', 'yuv420p', 'output.mp4']
proc = subprocess.Popen(cmd, **popen_params)


  


  However, with the '-shortest' flag, the resulting output.mp4 contains the entire audio, but only 1 frame of video data. What is going on here ?

  


• Concatination of images and videos in FFMpeg [closed]

  29 octobre 2023, par Juliano David Hilario

  I've been trying to concat pieces of videos with mix of images in FFMpeg and I can not achieve desired results. I'm trying to create a mock interview project for a friend, she answers the questions from a script. The question should be flashed in the screen before the footage of her answering is shown. The videos are encoded in H.265, with frame rate of 30fps, (via mediainfo) and when I try to concat the videos and images using the concat demuxer, it shows this message in rapid succession and only output the first image in the given duration in the output file : (meaning it failed when concating the video, I assume this is due to the fact that demuxed images doesn't have audio streams.)

  


  [png @ 0x55b4a4cb3540] Invalid PNG signature 0x3DB0201D430.
Error while decoding stream #0:0: Invalid data found when processing input


  


  the command I've used :

  


  ffmpeg -hide_banner -y -f concat -safe 0 -i concat.con -r 30 -c:v libx265 -c:a aac -pix_fmt yuv420p out.mp4


  


  the slice of concat.con file :

  


  file slides/1.png
duration 6
file parts/1.mp4
file slides/2.png
duration 8
file parts/2.mp4
file slides/3.png
duration 9
file parts/3.mp4
. . .
duration 12
file parts/9.mp4
file slides/10.png
duration 9
file parts/10.mp4



  


  Since, I need to get this done if possible today, I tried this route of turning the images into videos by this command :

  


  #!/bin/sh

ffmpeg -f lavfi -i anullsrc=channel_layout=stereo:sample_rate=44100 -loop 1 -i "${1}.png" -c:v libx265 -r 30 -c:a aac -t "$2" -pix_fmt yuv420p "${1}_slide.mp4"


  


  This does create the desired result of a static video without sound but still has an audio channel (which is a pre-requisite for the concat demuxer), but when I concat it with the same command above with videos, the videos' audio desyncs and advances, now the video delays with the audio, which is not obviously feasable for the project. I suspect it has to do with frames and PTS, as MPV (a media player) logs when the duration of the video enters the video that has been concatinated that the PTS is invalid, and says :

  


  Invalid audio PTS: 6.037188 -> 6.553832

Audio/Video desynchronisation detected! Possible reasons include too slow
hardware, temporary CPU spikes, broken drivers, and broken files. Audio
position will not match to the video (see A-V status field).


  


  Tried turning the pictures into an image, and was expecting it to atleast sync with the audio

  


• ffmpeg "Error reinitializing filters !" on some webm videos

  9 février 2023, par The Blind Hawk

  I have a dozen of webm videos I need to resize with the following :

  


  ffmpeg -i input.webm -vf “scale=w=360:h=270:force_original_aspect_ratio=2,fps=10,crop=360:270” output.webm


  


  I tried the command and it worked fine for some webm videos, but most of the returned the following error :

  


  [AVFilterGraph @ 0x7fcb3db076c0] No such filter: '“scale'
Error reinitializing filters!
Failed to inject frame into filter network: Invalid argument
Error while processing the decoded data for stream #0:0
[libopus @ 0x7fcb3c10a000] 1 frames left in the queue on closing
Conversion failed!


  


  I checked that ffmpeg still worked fine with previously successful files.
  
How can I get ffmpeg to work with the remaining wemb videos ?