[FFmpeg-user] How to calculate difference between wall clock start time of audio input and wall clock start time of video input from inside the asetpts filter?

Carl Eugen Hoyos ceffmpeg at gmail.com
Fri Feb 17 01:25:01 EET 2017

2017-02-16 11:09 GMT+01:00 David Bayles <davidbayles at gmail.com>:

> Lapaki:~ Lapaki$ /Users/Lapaki/Desktop/ffmpeg -f avfoundation -video_size
> 960x540 -pixel_format uyvy422 -framerate ntsc -thread_queue_size 8B -i
> "XI:none" -f avfoundation -thread_queue_size 8B -i "none:XI" -vf
> 'crop=iw-240:ih:120:0'

> -af 'asetpts=PTS+.58735/TB'

Why is asetpts needed?
Since both input streams show useful start times, I would
have expected that this is unnecessary...

Carl Eugen

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