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• Fixing audio/video out of sync when editing recorded broadcast

  27 décembre 2019, par sba

  I have recorded broadcast-ed material using a DVB-T tuner.

  That produces several TS files per recording (most likely to keep filesize within FAT32 limitations).

  I have concatenated each recording into a single TS file using :

  ffmpeg.exe -f concat -i $filelist -c copy -y $outputfile

  From there, I need to perform edits to remove commercials, strip extra stuff from the start and end, and optionally extract each episode into a separate file.

  I own Pinnacle Studio 23 Ultimate, that doesn’t support TS as input so I’m converting TS to MP4 using something like :

  ffmpeg -y -i foo.ts -crf 18 -ac 2 -r 25 -c:v libx265 -ar 48000 -b:a 192k -c:a aac -aspect 16:9 bar.mp4

  (I’ve tried several ways/options, including using HandBrake for that conversion).

  What happens is that in the resulting edited material, audio and video are out of sync. Can be in the whole file, or only in some sections.

  This could be linked to glitches (missing frames...) in the original recording.

  But when I play the original single-file TS, or the MP4 version, in any player such as VLC, audio and video are properly aligned. So these players are able to deal with the aforementioned glitches and "re-align" the audio and video streams.

  How can I "rewrite" the whole input file in such a way that audio and video are "fully synchronized" so that editing will be possible ?

  Thanks in advance for your help.

• How to not include the Pause duration in the FFMPEG recording timeline

  8 janvier 2019, par Riccardo Volpe

  I’m trying to pause a screencast made with ffmpeg under Linux, giving the command :

  kill -s SIGSTOP <pid>
  
  </pid>

  resuming then it with the command :

  kill -s SIGCONT <pid>
  
  </pid>

  to finally interrupt it with the command :

  kill <pid>
  
  </pid>

  but the resulting file keeps the duration of the pause command in the timeline. Is there any way to not include it in the final video output ?

  Thank you

  Edit #1

  I can’t understand a down vote without an explanation... but maybe my mind thinks different.

  To not be misunderstood and for a better explanation of the problem, I realized a video : as you can see, now, there are 14 seconds in which the timeline is locked (from 29th to 43th second), the same duration of the command to pause the screencast (kill -s SIGSTOP <pid></pid>). Now the previous question, if someone knows the solution.

  The unique one that I thought is to cut the final output, "labeling" the pause command in such a way to know where to cut...

• ffmpeg : Invalid data found when processing input

  20 septembre 2018, par Rich_F

  I have a situation where ffmpeg is throwing an error :

  Invalid data found when processing input

  I’ve reviewed other answers here, but my situation is different. I generate in Ruby, a text file with a list of input files I want to concatenate together into one large video.

  I generate in Ruby, the command meant for bash, which is also output for me to manually copy :

  ffmpeg -y -f concat -safe 0 -i /Volumes/Dragon2/Yums/randoms.txt /Volumes/Dragon2/Yums/final.mp4

  Throws an error :

  /Volumes/Dragon2/Yums/randoms.txt: Invalid data found when processing input

  Here is that file :

  file '/Volumes/Dragon2/Yums/0CEDC3CA-4571-4271-9938-A161EC2A887B.mov'
  
  file '/Volumes/Dragon2/Yums/0D25D907-D053-443B-AFC6-9F12B1711BBF.mov'
  
  file '/Volumes/Dragon2/Yums/6A272808-7706-435D-801E-ACE6B42EC749.mov'
  
  file '/Volumes/Dragon2/Yums/6E9BA2F1-C5E7-4C1C-B290-D116105732FA.mov'
  
  file '/Volumes/Dragon2/Yums/0A41C7B7-74CE-484E-B029-3AE57B8BB4EA.mov'

  When bash runs it, it complains about the input file randoms.txt having invalid data. When I copy and paste the very same command in bash, it works fine. I’m stumped as to how the two are different and why ffmpeg is not happy when initiated in the shell.

  How can I get this to work ? What am I missing ? Cheers

  EDIT : Original ruby code :

  `clear`
  
  require 'pathname'
  
  require 'pp'
  
  
  
  s = '/Volumes/Dragon2/Yums'
  
  files = []
  
  
  
  Dir.foreach(s) do |path|
  
    files << "#{ s }/#{ path }"  
  
  end
  
  
  
  result = files.sample(files.size)           # randomizer
  
  
  
  f = File.open("#{ s }/randoms.txt", 'w+')
  
  result.each_with_index do |item, i|
  
    pp "#{ i }: #{ item }" if item.include?('mov')
  
    f << "file '#{ item }'\n" if item.include?('mov')
  
  end
  
  
  
  `echo `
  
  
  
  File.delete("#{ s }/final.mp4") if File.exists?("#{ s }/final.mp4")
  
  s = "ffmpeg -y -f concat -safe 0 -i #{ s }/randoms.txt #{ s }/final.mp4"
  
  puts s
  
  
  
  sleep 3
  
  `#{ s }`

  I have also tried system s as well with the same error. The syntax is generated fine, output fine, operates fine manually.