Pfthb

I wanted to run a PSNR check on a encoded segment but avoid extracting the segment in a lossless codec first for comparsion. I just wanted to trim the input, however it looks like this is disabled.

My command:

ffmpeg -i original.mp4 -i segment.mp4 -filter_complex "[0:v]trim=10:20,setpts=PTS-STARTPTS[0v];[1:v]setpts=PTS-STARTPTS[1v];[0v][1v]psnr" -f null -

This will run through the whole original input file and not trim the video in the filter.

If I try to trim the input with -ss and -t, only the input -ss flag is working. It will set the input correct but ignore the -t timestamp.

ffmpeg -ss 10 -i original.mp4 -t 10 -i segment.mp4 -filter_complex [0:v][1:v]psnr -f null - 

Different placement of the -t will have no effect.

I also tried to set the duration in trim while keeping the -ss input which is working.

ffmpeg -ss 10 -i original.mp4 -i segment.mp4 -filter_complex "[0:v]trim=duration=10,setpts=PTS-STARTPTS[0v];[1:v]setpts=PTS-STARTPTS[1v];[0v][1v]psnr" -f null - 

I did try this with end and end_frame but neither one worked.

The same applies if I use -lavfi instead of -filter_complex.

I did have a brief look at the sourcecode of the PSNR filter but could not find any refrences to trim or -t.

Is this function blocked or am I doing something wrong?
Would there be an alternative way to doing this without encoding a lossless version of the same segment to compare?

The original command is almost fine. However, the order of inputs should be swapped, and if there's any audio, that should be disabled.

ffmpeg -i original.mp4 -i segment.mp4 -filter_complex "[0:v]trim=10:20,setpts=PTS-STARTPTS[0v];[1:v]setpts=PTS-STARTPTS[1v];[1v][0v]psnr" -an -f null -

Also, in the snippet below

ffmpeg -ss 10 -i original.mp4 -t 10 -i segment.mp4

if you meant to limit the duration of original.mp4, then -t 10 should be placed before -i original.mp4.