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• ffmpeg out of sync after split and put together

  5 septembre 2017, par LaborC

  Looking for the correct way to encode a given input video in multiple bitrates and then package it for dash and hls. I thought this is a basic task, but as it turns out, I could not find a best practise on how to achieve this.
  So the way I do it is (but with these I get an out of sync video/audio) :

  First I split my video (mp4) into video and audio.

  ffmpeg -c:v copy -an video_na.mp4 -i source_input.mp4
  
  ffmpeg -c:a aac -ac 2 -async 1 -vn audio.mp4 -i source_input.mp4

  Then I encode the video with the following commands :

      ffmpeg.exe -i video_na.mp4 -an -c:v libx264 -crf 18 \
  
  -preset fast -profile:v high -level 4.2 -b:v 2000k -minrate 2000k \
  
  -maxrate 2000k -bufsize 4000k -g 96 -keyint_min 96 -sc_threshold 0 \
  
  -filter:v "scale='trunc(oh*a/2)*2:576'" -movflags +faststart \
  
  -pix_fmt yuv420p -threads 4 -f mp4 video-2000k.mp4
  
  
  
      ffmpeg.exe -i video_na.mp4 -an -c:v libx264 -crf 18 \
  
  -preset fast -profile:v high -level 4.2 -b:v 1500k -minrate 1500k \
  
  -maxrate 1500k -bufsize 3000k -g 96 -keyint_min 96 -sc_threshold 0 \
  
  -filter:v "scale='trunc(oh*a/2)*2:480'" -movflags +faststart \
  
  -pix_fmt yuv420p -threads 4 -f mp4 video-1500k.mp4

  After that I fragment the videos.

  mp4fragment --fragment-duration 4000 --timescale 10000 video-2000k.mp4 \
  
  video-2000k-f.mp4
  
  
  
  mp4fragment --fragment-duration 4000 --timescale 10000 video-1500k.mp4 \
  
  video-1500k-f.mp4

  And finally package everything together again for dash.

  mp4dash --media-prefix=out  \
  
        --use-segment-timeline  \
  
        video-2000k-f.mp4  \
  
        video-1500k-f.mp4  \
  
       --out dash

  Now there is a difference between audio and video.

  I think that the problem is with my parameters for encoding. But which one I have no idea.
  What am I doing wrong ?

• How to convert a lump set of PPM files to a single .mp4 video using ffmpeg

  4 août 2021, par Nash G-L

  I'm trying to convert some .ppm files into a single video using ffmpeg. The images are listed as image10.ppm, image20.ppm, all the way up to image2000.ppm

  


  Essentially, there are 200 images following the format of image(1-200)0.ppm in a single folder.

  


  I've navigated to the correct folder containing the images using cd and the terminal displays this folder as the directory I'm in.

  


  Inputting the following command into the terminal :

  


  ffmpeg -r 10 -f image2 -s 500x500 -i image%04d.ppm -vcodec libx264 -crf 25  -pix_fmt yuv420p presentation_video.mp4


  


  I get the error that says :

  


  [image2 @ 0x7ff36180ba00] Could find no file with path 'image%04d.ppm' and index in the range 0-4
image%04d.ppm: No such file or directory


  


  What am I missing ? I've just downloaded ffmpeg and am fairly new in general to command line interface.

  


• PHP's exec() not executing command for FFmpeg

  16 septembre 2011, par tundoopani

  I have installed ffmpeg on my server and it works fine via my terminal. I'm able to successfully convert a file to webm format, so I'm sure the installation is fine. I'm also sure that I only have one installation of ffmpeg installed on my machine.

  A problem arises when I try to convert files through PHP via PHP's exec(). When I run the same commands, I ran in the terminal, nothing happens. I looked around stackoverflow and other parts of the net for some help. I tried this to see the output :

  exec($cmd, $out, $rv);
  
  echo "output is:\n".implode("\n", $out)."\n exit code:$rv\n";

  The output is : "output is : exit code:127"

  The command I'm using is in this format :

  ffmpeg -i "sample.mov" -vcodec libvpx  -r 30 -b "644k" -acodec libvorbis -ab 128000   -ar "44100" -ac 2 -s "352x198" "sample.webm"

  I've tried replacing "ffmpeg" with the full path to FFmpeg but that did not work.

  Why isn't the script running the command correctly and converting the files ?

  Thank you !