[FFmpeg-user] Problem with ffmpeg psnr calculate filter when image file applied

[肖谋]

Dear all,
   I would like to calculate the PSNR of two images or two videos. I found
that the new psnr filter worked well for video files which have at less two
frames, but not for one frame, or image files.

ffmpeg version is 2.0.2
generate the files to be compared
two frames video: ./ffmpeg -i test.mkv -vframes 2 -vcodec libx264 -an
frame2.mkv
one frames video: ./ffmpeg -i test.mkv -vframes 1 -vcodec libx264 -an
frame1.mkv

this one does not work:
./ffmpeg -i test.mkv -vframes 1 -vcodec rawvideo -filter:v
"movie=frame1.mkv,setpts=PTS-STARTPTS[main];[in][main]psnr=f=c.log" -f
rawvideo -y /dev/null

this one works:
./ffmpeg -i test.mkv -vframes 1 -vcodec rawvideo -filter:v
"movie=frame2.mkv,setpts=PTS-STARTPTS[main];[in][main]psnr=f=c.log" -f
rawvideo -y /dev/null

This situation can also be reproduced using image files.
I looked into the vf_psnr.c. The do_psnr is not called.

I think this might be a bug for filter process? any suggestions to fix this?

Thanks a lot.

Regards