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• Turn image sequence into video with transparency

  5 juillet 2020, par Cody Hatch

  I've got what seems like it should be a really simple problem, but it's proving much harder than I expected. Here's the issue :

  



  I've got a fairly large image sequence consisting of numbered frames (output from Maya, for what its worth). The images are currently in Targa (.tga) format, but I could convert them to PNGs or other arbitrary format if that matters. The important thing is, they've got an alpha channel.

  



  What I want to do is programatically turn them into a video clip. The format doesn't really matter, but it needs to be lossless and have an alpha channel. Uncompressed video in a Quicktime container would probably be ideal.

  



  My initial thought was ffmpeg, but after wasting most of a day on it it seems it's got no support at all for alpha channels. Either I'm missing something, or the underlying libavcodec just doesn't do it.

  



  So, what's the right way here ? A command line tool like ffmpeg would be nice, but any solution that runs on Windows and could be called from a script would be fine.

  



  Note : Having an alpha chanel in your video isn't actually all that uncommon, and it's really useful if you want to composite it on top of another video clip or a still image. As far as I know uncompressed video, the Quicktime Animation codec, and the Sorenson Video 3 codec all support tranparency, and I've heard H.264 does as well. All we're really talking about is 32-bit color depth, and that's pretty widely supported ; both Quicktime .mov files and Windowss .avi files can handle it, and probably a lot more too.

  



  Quicktime Pro is more than happy to turn an image sequence into a 32-bit .mov file. Hit export, change color depth to "Millions of Colors+", select the Animation codec, crank the quality up to 100, and there you are - losslessly compressed video, with an alpha chanel, and it'll play back almost anywhere since the codec has been part of Quicktime since version 1.0. The problem is, Quicktime Pro doesn't have any sort of command-line interface (at least on Windows). ffmpeg supports encoding using the Quicktime Animation codec (which it calls qtrle), but it only supports a bit-depth of 24 bits.

  



  The issue isn't finding a video format that supports an alpha channel. Quicktime Animation would be ideal, but even uncompressed video should work. The problem is finding a tool that supports it.

  


• FFMPEG - can you have comments in script files ?

  23 juillet 2024, par rossmcm

  Because of batch's poor ability to handle multi-line strings, I'm using FFMPEG script files more and more for filter_complex arguments. I'm wondering if there is any way to include comments in these files. They seem to be quite tolerant of white space and line breaks. I've tried :

  


  #
#   comment
#


  


  and

  


  ;
;   comment
;


  


  and

  


  `
`   comment
`


  


  and

  


  '
'   comment
'


  


  with no success. It doesn't look as if comments are officially supported, but I'm wondering of there is some syntax quirk that allows them ?

  


  *** CLARIFICATION ***

  


  I'm not talking about comments in batch files here, but comments in filter_complex_script files. FFMPEG supports specifying the filter_complex argument string in a separate file. So instead of :

  


  ffmpeg -i "input.mp4" -filter_complex "[0:v] crop=w=100:h=100:x=12:y=34 " "output.mp4"


  


  you can specify :

  


  ffmpeg -i "input.mp4" -filter_complex_script "crop.txt" "output.mp4"


  


  where crop.txt contains

  


  [0:v] crop=w=100:h=100:x=12:y=34


  


  This is really handy when the filter_complex string gets more complicated (I routinely deal with arguments 10,000 characters in length).

  


• FFMPEG zoompan for continuous zoom in/zoom out from start duration

  10 juillet 2020, par Nikhil Solanki

  I am creating continues zoomin/zoomout effect for input image using this command :

  


  ffmpeg -i combine.mp4 -i image1.jpg -filter_complex "[0]split=2[color][alpha]; 
[color]crop=iw/2:ih:0:0[color]; [alpha]crop=iw/2:ih:iw/2:ih[alpha]; [colo][alpha]alphamerge[v1];
[1]scale=540*2:960*2, setsar=1, zoompan=z='if(lte(zoom,1.0),1.02,max(1.001,zoom-0.0015))':d=25*0.25:x='iw/2-(iw/zoom/2)':y='ih/2-(ih/zoom/2)':s=540x960[v2]; 
[v2]zoompan=z='if(gte(zoom,1.1),1.0,min(zoom+0.0015,1.1))':d=25*0.25:x='iw/2-(iw/zoom/2)':y='ih/2-(ih/zoom/2)':s=540x960[v2];
[v2]curves=vintage, format=yuv444p[v2];
[v2][v1] overlay=1" output_video.mp4 -y


  


  This command will continues zoomin and zoomout input image1.jpg for 1 second and stop after 1 second its OK. But problem is I want perform zoomin zoomout effect after 5 second of video. Video duration is 20s. So, how can I perform zoompan after some duration.