[FFmpeg-user] ffprobe -show_frames and coded_picture_number

[Richard H Lee]

I use ffprobe -show_frames to find out the exact frame rate of videos 
that stray away from 24000/1001 fps before conversion to 25 fps so that 
I can get accurate a/v sync when I speed up the audio.

I basically use pkt_pts_time / coded_picture_number of the very last 
frame for the overall frame rate.

The problem is that on large files, it can take quite a while to dump 
all the frame data.

Is it possible to just dump the last few frames / seconds of the file?
Or would this affect coded_picture_number? (I'm not sure if 
coded_picture_number is counted by keeping track of frames/packets or is 
stored within the packet itself.)