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• Capture ffmpeg's metadata output in powershell

  17 mars 2016, par xdhmoore

  I’m trying to capture the output of ffmpeg in PowerShell(tm) to get some metadata on some ogg & mp3 files. But when I do :

  ffmpeg -i file.ogg 2>&1 | sls GENRE

  The output includes a bunch of lines without my matching string, "GENRE" :

        album_artist    : Post Human Era
  
        ARTIST          : Post Human Era
  
        COMMENT         : Visit http://posthumanera.bandcamp.com
  
        DATE            : 2013
  
        GENRE           : Music
  
        TITLE           : Supplies
  
        track           : 1
  
  At least one output file must be specified

  I am guessing something is different in the encoding. ffmpeg’s output is colored, so maybe there are color control characters in the output that are breaking things ? Or, maybe ffmpeg’s output isn’t playing nicely with powershell’s default UTF-16 ? I can’t figure out if there is another way to redirect stderr and remove the color characters or change the encoding of stderr.

  EDIT :
  Strangely, I also get indeterminate output. Sometimes the output is as shown above. Sometimes with precisely the same command the output is :

        GENRE           :

  

  Which makes slightly more sense, but is still missing the part of the line I care about (’Music’).

  Somewhere powershell is interpreting something as newlines that is not newlines.

• How to concatenate multiple MP4 videos with FFMPEG without audio sync issues ?

  25 mars 2016, par sb3k

  I have been trying to concatenate a number of MP4 clips (h264,aac) using the FFMPEG concat protocol documented here. The clips concatenate successfully, however there are multiple errors in the logs including :

  • Non-monotonous DTS in output stream
  • Past duration too large

  Additionally, it seems that the audio and video go slightly out of sync as more clips are added - though it is more noticeable on certain players (Quicktime & Chrome HTML5).

  Here is the code I am using, any tips would be appreciated !

  Convert each video to temp file

  ffmpeg -y -i <input file="file" /> -vcodec libx264 -acodec aac -f mpegts -bsf:v h264_mp4toannexb -mpegts_copyts 1 <temp file="file"></temp>

  Concat temp files

  ffmpeg -i concat  -map 0 -vcodec copy -aprofile aac_low -acodec aac -strict experimental -cutoff 15000 -vbsf aac_adtstoasc -b:a 32k <output file="file"></output>

• FFmpeg zoom not smooth-centered (but zigzag)

  10 juin 2016, par SebSob

  I try to perform a basic zoompan with FFmpeg. I have an input image (.png 1280x720) and i create an 8 seconds video (.mp4 320x180) from it, with a zoom. This is my command :

  ffmpeg -loop 1 -i in_img.png -c:v libx264 -pix_fmt yuv420p -strict experimental -framerate 25 -vf zoompan=z=’min(zoom+0.011835363,2.1835363)’:d=375:x=400:y=247 -s 320x180 -t 00:00:08.882 out_vid.mp4

  Everything works...but the zoom is not looking okay. It is going zig-zag.

  Does anyone know how to make it zoom smooth, like centered ? (And not first left then right)

  Thanks

  EDIT

  ---

  I’ve come a small step closer to a solution by slightly modifying the ’x’ and ’y’ in the -vf filter (rest of the command is the same as above) :

  -vf
  zoompan=z=’min(zoom+0.022,3.25)’:d=375:x=’if(gte(zoom,3.25),x,x+8.24)’:y=’if(gte(zoom,3.25),y,y+4.72)’:s=1280x720

  I incement x and y every frame (for x +8.24, for y +4.72, i know those values because i know how many frames it takes get to the end-zoom state) so that it will move to its end zoom state coordinate (1011,582), see image :

  
  This is the video of the result, as you can see it does not do the zig-zag effect, but now it looks like its going first to the center and then to the zoomed result. Or is that only an illusion ??
  Any idea’s ?