Variable framerate lossless video from yuv422 images

Question

I've been pulling my hair lately with FFmpeg commandline. Be aware that I am not an FFmpeg expert. Here is my problem:

I have a bunch of YUV422 images as such:

image0.yuv
image1.yuv
..
image450.yuv

Along with these I have a file containing timestamps for every image, say:

timestamps.txt

I would like to encode a lossless video (maybe with -c:v libx264 -pix_fmt yuv422p) from these with every image displayed at its correct timstamp. Here are the things I tried in vain:

• use -f concat and provide a file containing a list like this:

  file 'image0.yuv'
  duration '0.0515'
  file 'image0.yuv'
  duration '0.0721'
  ... etc
  

  this solution does not work because I need to provide a frame size (which is not included in the raw yuv files)

• something like cat *.yuv | ffmpeg -f rawvideo -s 800x600 -pix_fmt yuv422p -framerate 0.5 -i - -c:v libx264 -pix_fmt yuv422p out.mp4 which doesn't work neither because I can't provide it timestamps for each image (variable framerate) but just use the fixed -framerate argument

• I'm aware of the -vsync vfr argument but can't manage to make it work properly

I would be eternally grateful for any piece of advice, thanks :)

Answer 1

It's not possible to specify common input options for the concat demuxer. Quick and dirty workaround: convert all YUV images to something that can be read without having to specify further options. For example:

for f in *.yuv; do ffmpeg -f rawvideo -s 320x240 -pix_fmt yuv422p -i "$f" "${f%%.yuv}.avi"; done

Then, construct your concat file with the AVI files instead.

Or, with GNU parallel:

parallel 'ffmpeg -f rawvideo -s 320x240 -pix_fmt yuv422p -i {} {.}.avi' ::: *.yuv

Or use the method linked to in the comments wherein you can pipe the YUV images and later modify the CFR timestamps of the generated file to become VFR.