[FFmpeg-user] Getting precise start time from wall-clock for capture

[Arthur Wait]

>
> I see the timestamp of the first frame "reset" to 0 - is that what you
> mean with "normalize"?
>

Here's what seems to have worked for me:

ffmpeg -f v4l2 -framerate 60 -video_size 1920x1080 -ts mono2abs -i
/dev/video-static -r 2997/100 -f matroska -c:v nvenc -b:v 25000k -minrate
25000k -maxrate 25000k -g 1 -profile:v high -preset hq -copyts output.mkv

It took me a few tries to get the -ts mono2abs and -copyts into the right
location, but now I believe I'm getting good wall-clock time (at least, it
looks logical to me). I'm still doing some testing, though...