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• FFMPEG - Merging Videos with Transparency

  4 juillet 2013, par user1829136

  I am trying to merge two videos together, both have transparency, using the command

  ffmpeg.exe -i person2.mov -vf "[in] scale=iw/2:ih/2,fade=out:300:30:alpha=1, pad=2*iw:ih [left] ; movie=person2.mov, scale=iw/2:ih/2,fade=out:300:30:alpha=1 [right] ; [left][right] overlay=main_w/3:0,fade=out:300:30:alpha=1 [out]" -b:v 768k Output_people.mov

  By doing that I get the following output :

  http://i263.photobucket.com/albums/ii122/Fernando461/Untitled.png

  As you can see, it was possible to get the two videos to be on top of each other. But then, when I try to merge this video (Output_people.mov) with another video, it doesn't have the same transparency. Is it possible to keep transparency in the outcome ?

  Edit 1 :

  This is the output I get : https://www.dropbox.com/s/gpid1pptfio31gd/ffmpeg-20130701-193206.log

  And by "it doesn't have the same transparecy" I meant that the background is black instead of being transparent, so if I put one video on top of each other, the one in the back is covered by a black part of the one in the front.

  Edit 2 :
  Adding -vcodec qtrle to the code worked. Thanks mark4o !

• FFmpeg Audio Desync Issue

  20 septembre 2016, par Kyle J

  I’ve seen tons of threads about these but nothing seems to have changed for my problem.

  Currently inside my Java program, I am calling the command line and using this command.

  ProcessBuilder builder = new 
  
                   ProcessBuilder(
  
                           "cmd.exe", "/c", "ffmpeg -y -i " + "\"" + inputFile + "\" -vcodec libx264 -async 1 -f mp4 " + " -ss " + offset + " -c copy -t " + duration + " " + "\"" + outputFile + "\"");

  Originally -vcodec, -async, and -f mp4 weren’t there but in efforts to hopefully correct the audio, they have been placed there.

  The audio is lagged by about 1-2 seconds, I was wondering if anyone had any ideas ? I’ve also tried to manually set the frame rate which still hasn’t worked.

  Here is another failed attempt.

  ProcessBuilder builder = new 
  
                   ProcessBuilder(
  
                           "cmd.exe", "/c", "ffmpeg -y -i " + "\"" + inputFile + "\" -vcodec libx264 -async 1 -acodec libfaac -ab 128k -ac 2 -bt 5000k -b 5000k -r 59.940 -threads 0 -f mp4 " + " -ss " + offset + " -c copy -t " + duration + " " + "\"" + outputFile + "\"");

  Input & Output files along with Offset and Duration are all fine, please don’t question this.

  Quick edit !

  The input file will always have the extension .flv

  Another EDIT
  When I remove the offset and duration arguments and use copyts instead, the entire file is converted to mp4 AND the audio is synced. The issue seems to lie in the offset and duration since I tried copyts before with the two but it still was desync’d.

  Current

  ProcessBuilder builder = new 
  
                   ProcessBuilder(
  
                           "cmd.exe", "/c", "ffmpeg -y -i " + "\"" + inputFile + "\"" + " -c copy -copyts " + "\"" + outputFile + "\"");

• FFMPEG Customized Quantization

  16 février 2018, par Shailender Jain

  Can i use customised quantization table in FFMPEG. Is there any available option ? If there is no option then where i can edit in the code. For e.g. while compressing JPEG custom quatization table can be give as a parameter