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• FFMPEG h264 grey frame and artifacts at beginning

  28 novembre 2011, par marce002

  I'm splitting my "zi6 quicktime mov" hd videos, I have 250 clips of around 10 or 15 seconds each, from lot of places, locationes around the globe and want to combine them in a single big clip.

  I can merge them very good with "mkvmerge".

  The problem is that the first frames of all videos in the collection (splitted with ffmpeg), are gray or with artifacts at beggining, I do not know how to explain, maybe wrong ffmpeg commands, I'm doing this (with batch command line, which is great / fast for me) :

  =======begin of batch file

  ffmpeg -i jockey_club_fpv.mov -ss 00:00:17 -t 00:00:24 -g 1 -sameq -vcodec copy -vf fade=in:0:30 partes3a.mov
  
  ffmpeg -i jockey_club_fpv.mov -ss 00:04:40 -t 00:00:20 -g 1 -sameq -vcodec copy -vf fade=in:0:30 partes3b.mov
  
  ffmpeg -i jockey_club_fpv.mov -ss 00:05:35 -t 00:01:00 -g 1 -sameq -vcodec copy -vf fade=in:0:30 partes3c.mov
  
  ffmpeg -i jockey_club_fpv.mov -ss 00:07:11 -t 00:00:10 -g 1 -sameq -vcodec copy -vf fade=in:0:30 partes3d.mov
  
  ffmpeg -i jockey_club_fpv.mov -ss 00:07:45 -t 00:00:21 -g 1 -sameq -vcodec copy -vf fade=in:0:30 partes3e.mov
  
  ffmpeg -i jockey_club_fpv.mov -ss 00:08:47 -t 00:00:05 -g 1 -sameq -vcodec copy -vf fade=in:0:30 partes3f.mov
  
  ffmpeg -i jockey_club_fpv.mov -ss 00:09:18 -t 00:00:10 -g 1 -sameq -vcodec copy -vf fade=in:0:30 partes3g.mov
  
  ffmpeg -i jockey_club_fpv.mov -ss 00:09:35 -t 00:00:09 -g 1 -sameq -vcodec copy -vf fade=in:0:30 partes3h.mov
  
  ffmpeg -i jockey_club_fpv.mov -ss 00:10:07 -t 00:00:16 -g 1 -sameq -vcodec copy -vf fade=in:0:30 partes3i.mov
  
  mkvmerge -o join4.mov partes3a.mov + partes3b.mov + partes3c.mov + partes3d.mov + partes3e.mov + partes3f.mov + partes3g.mov + partes3h.mov + partes3i.mov

  =======end of batch file

  Thanks a lot for any answer !!

• System command - doesn't get return

  28 novembre 2011, par waxical

  Seem to have a problem with PHP system command - I place a command with it and if return code is above 0 - I cite failure otherwise I carry on.

  It never seems to return on FFMPEG commands lower than a certain number of seconds (generally 3-5 seconds duration video encodes that are very quick to encode). Is this something that'd be from FFMPEG not returning properly or system command ?

  An example command :-

  system('ffmpeg -i /home/test.wmv -f flv 340x160 -vcodec libx264 export.flv', $returnCode);
  
  if($returnCode > 0) { error(); }

  The only way to get round this seems to be to run a timer and check log files if nothing back after an amount of time but if anyone has any pointers - be gratefully received.

• How to optimize video to animated GIF conversion using PHP + shell commands

  15 mars 2012, par user1070798

  I have a web application that converts any video into an animated GIF. The app runs in PHP and the following steps are executed through php's shell_exec :

  1. Scale video to smaller dimensions, if they are large (ffmpeg -i $in -s 200x150 -an $out)
  2. Use ffmpeg to extract 1 jpeg every x seconds (ffmpeg -i $in -ss $ss -vframes 1 $out)

  3. Convert jpegs to animated GIF using imagick (convert -delay $delay -loop 0 $dir/* $out)

     aside - the reason I don't use the ffmpeg gif89a output is because the quality sucks.

  I want to be able to except any major image format, but the most common will probably be .flv (flash) and .avi/.mpg.

  My application runs fine, but I am a perfectionist and it needs to be faster for scalability.

  My web server has 16 cores and I would like to utilize them as much as possible, but .flv multi-threading appears to not be supported by ffmpeg, while .avi and some others are supported. Also, ffmpeg doesn't support multi-threading when outputting to jpegs.

  Does anyone know of any other programs that support multi-threading for .flv and others ? Are there any more efficient methods to create an animated GIF from video, while maintaining relatively decent quality (aka not the 100-color palette that ffmpeg supports) ?

  Also, if anyone knows which codecs might perform best for stages 1 and 2, particularly with flv, I'd love to know. I've done hours of testing, but there are just so many options I haven't come to any solid conclusions.

  ***Update : My online app is working well so far animated gif generator. I would still love to make it faster though, so if anyone has run into similar circumstances... let me know !