[FFmpeg-user] Questions about PTS/DTS shifting

[Massimo Battistel]

hello,
I have this theoretical question:

Suppose a video with 2 tracks a/v (25fps, uncompressed so that pts=dts)
made like that (timebase is 1/1000 for both tracks):

first video pts = 40
first audio pts = 72

I would like to reach at least one of the following goals:

A: Shifting one track to 0 keeping sync with audio:
first video pts = 0
first audio pts = 32

B: Using padding (to keep sync), having audio pts=video pts
first video pts = 40
first audio pts = 40

C: This would be the best. both pts starts from 0 with sync.
first video pts = 0
first audio pts = 0 (with padding)


How to do that with a single command line and without having to previously
parse file to know first_pts values?


With [a]setpts filters I could shift timecodes but video filter don't know
anythig about audio pts, so I need to know pts values previously.

With areasmple:first_pts=x I have to know first video pts.

Any suggestions?

Thanks,
MB