[FFmpeg-user] multiple inputs

[Mikael Persson]

Hi, I want to sequentially parse a set of input videos and output all their
keyframes in monotonic unbroken order...

so videos a,b,c,d with 10 frames each should produce 0-50.jpg

If thye videos where concatable and the concat process lossless I could do

ffmpeg -f concat -i vids.txt concat.vid
and then
ffmpeg  vsync -skip_frame nokey -i concat.vid %06d.jpg

But they arent, and it isnt...

tips?