[FFmpeg-devel] [PATCH 3/3] avdevice: use av_gettime_relative() for timestamps

[Kieran Kunhya]

On Sun, 7 Feb 2021, 14:21 Nicolas George, <george at nsup.org> wrote:

> Marton Balint (12021-02-07):
> > av_gettime_relative() is using the monotonic clock therefore more
> suitable as a
> > timestamp source and for relative time calculations.
> >
> > Probably fixes ticket #9089.
>
> Not ok.
>
> This is a user-visible change of behavior, we cannot do it just like
> that.
>
> Furthermore, for devices, timestamps are not only needed to synchronize
> between devices within the same computer, they may be needed to
> synchronize between devices connected to different computers, or between
> devices and other network streams (IP webcams are the obvious example).
>

It is wrong to suggest that the clock of an IP webcam has any relation at
all to the PC clock both absolute or relative.

The best course of action is to generalize what was done with v4l: make
> it an option.
>

This is as usual a major flaw in v4l2. The monotonic clock should always be
used. It's the least-worst clock.

Kieran

Regards,
>
> --
>   Nicolas George
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