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• FFMPEG - Concat and Alpha transition

  4 juin 2018, par Jacques Marcel

  I’m looking for a FFMPEG expert to help me with some video editing :)

  I want to Add Intro & Outro to a lot of videos but I have a problem with "Concat" trying to use a Alpha transition for the Intro, let me explain :

  I have 3 files :

  1 - Intro (4s), with an 1s Alpha transition at the end of the file (3s => 4s)

  2 - Video (2h)

  3 - Outro (20s)

  I have succeeded to merge my file with this command :

  ffmpeg -i Intro.mov -i Movie.mp4 -i Outro.mov -filter_complex 
  
  "[0:v:0][0:a:0][1:v:0][1:a:0][2:v:0][2:a:0]concat=n=3:v=1:a=1[outv][outa]"
  
   -map "[outv]" -map "[outa]" output.mp4

  But I would like to see my 2nd file under the 1st when the alpha transition begin.

  Right now the videos just play one after the other and I got black frames during my alpha transition. (2nd video play after the end of the 1st)

  If anyone have the time to give me the tips to play my 2nd video before the 1st end

  Thanks for your time !

• ffmpeg overlay filter : maintain audio and video quality

  30 avril 2018, par Dave Hollingworth

  I’m adding a watermark to a video using the ffmpeg overlay filter, and I want to preserve the original quality of the video. This is the output of ffmpeg -i for the original video :

  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'original_recording.mp4':
  
    Metadata:
  
      major_brand     : isom
  
      minor_version   : 512
  
      compatible_brands: isomiso2mp41
  
      encoder         : Lavf57.25.100
  
    Duration: 00:03:59.13, start: 0.000000, bitrate: 1932 kb/s
  
      Stream #0:0(und): Video: mpeg4 (Simple Profile) (mp4v / 0x7634706D), yuv420p, 1472x828 [SAR 1:1 DAR 16:9], 1796 kb/s, 24.96 fps, 25 tbr, 12800 tbn, 25 tbc (default)
  
      Metadata:
  
        handler_name    : VideoHandler
  
      Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 129 kb/s (default)
  
      Metadata:
  
        handler_name    : SoundHandler

  and this is the command I’m using to overlay an image file in the bottom right hand corner (basically a watermark) :

  ffmpeg -i original_recording.mp4 -i watermark.png -filter_complex "overlay=W-w-45:H-h-35" -c:v libx264 -strict -2 output.mp4

  I added the libx264 option becausee the output was coming out all wibbly. However, when I use this, the size of the output file is much smaller than the original. (There’s no noticeable loss in quality when I play the video, but I’d rather not lose quality if possible). I’m very much not an expert on video formats, to be honest I’m a bit lost.

  I’ve tried the -crf option but that gives this error message :

  Codec AVOption crf (Select the quality for constant quality mode) specified for output file #0 (output.mp4) has not been used for any stream. The most likely reason is either wrong type (e.g. a video option with no video streams) or that it is a private option of some encoder which was not actually used for any stream.

  What would be the best way to overlay an image as a watermark whilst preserving the quality of the original video as much as possible ?

• How to convert MKV movies 5.1 audio tracks to 2.0 (Stereo) but keep the original ones

  9 avril 2018, par aur0n

  To solve a problem I had where 5.1 movies had really quite dialogues, I’m using FFMPEG to convert every audio track of my MKV movies to an 2.0 track with audio normalization, leaving video and subtitles intact.

  Here’s what the command looks like :

  for /r %%i in (*.mkv) do (
  
      @ffmpeg.exe -hide_banner -v 32 -stats -y -i "%%i" -map 0:v -map 0:a -map 0:s? -c:s copy -c:v copy -acodec ac3 -ac 2 -ar 48000 -ab 640k -af %aproc2%  -f matroska "%%~ni [Stereo].mkv"
  
  )

  What I’d like to do now is having these converted audio track added to the MKV among the 5.1 tracks, and not replacing the originals, which I may want in future.

  I’m not really an expert of FFMPEG, so I’m looking for some help.