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• How to stack several videos using ffmpeg ?

  13 juillet 2019, par John

  I have four cameras that are recording videos and wand to stack all videos into one video file. The final video must be a 2x2 grid.

  

  THE HARD PART is that sometimes cameras are not recording simultaneously.

  Here you can see one situation of how cameras are recording :

  Camera 1 timeline: |recording....................................|
  
  Camera 2 timeline: |stopped....|recording........................|
  
  Camera 3 timeline: |recording.........|stopped....|recording.....|
  
  Camera 4 timeline: |recording..................|stopped..........|

  Explanation :

  • Camera 1 is recording all time.
  • Camera 2 is starting recording later.
  • Camera 3 is recording, then stopped a period of time, then again recording.
  • Camera 4 is recording a period of time, then stopped.

  In the final video I want to synchronize each video by timestamps.

  If a camera is stopped a period of time then at its position must be a black portion.

  How can I do this ?

• FFMpeg : CFLAGS=-D__STDC_CONSTANT_MACROS ./configure where ?

  24 avril 2013, par olidev

  I got this problem " 'UINT64_C' was not declared in this scope" while using the ffmpeg library for Eclipse running under Ubuntu.

  After a while, I have found this solution : http://code.google.com/p/ffmpegsource/issues/detail?id=11

  But I could not know how to this :

  This should be fixed in our build system no matter what version of ffmpeg you're using. If you're still getting it, run configure like so :
  CFLAGS=-D__STDC_CONSTANT_MACROS ./configure
  and your problems should go away. This applies to other C++ programs using ffmpeg as well and not just to ffms2, but I can't guarantee that other programs won't break if you define that macro (they really shouldn't, though).

  Where can I run the configure ? from Terminal ? I tried with Terminal but it does not work.

  Anybody has an idea how to run the configure ?

  Thanks in advance and your help is much appreciate !

• How to queue ffmpeg FIFO

  29 avril 2013, par Francois

  we build a service similar to youtube. Also converting runs fine with ffmpeg using this script from another post here :

  How do I set up an ffmpeg queue ?

  #!/bin/bash
  
  
  
  pipe=/tmp/ffmpeg
  
  
  
  trap "rm -f $pipe" EXIT
  
  
  
  # creating the FIFO    
  
  [[ -p $pipe ]] || mkfifo $pipe
  
  
  
  while true; do
  
  # can't just use "while read line" if we 
  
  # want this script to continue running.
  
  read line < $pipe
  
  
  
  # now implementing a bit of security,
  
  # feel free to improve it.
  
  # we ensure that the command is a ffmpeg one.
  
  [[ $line =~ ^ffmpeg ]] && bash <<< "$line"
  
  done

  This works pretty good when i send one by one to the named pipe. When i send more than one at same time the second one queues the terminal to the point the first one finished. if a try more than 2 the third one will not be transcoded.

  So i tried to workaround with background sending to get the terminal free (just drop the echo command and close the ssh connection) but this doesn't work, then i played around with screen -X but also no luck. Maybe someone has a good idea to deal this.

  What i wanna do is : Every uploaded video which is needed to transcode will send a echo to the named pipe. FIFO should match but not blocking the terminal. So i think i need something to really queue ffmpeg input.

  kindest regards
  Francois