[Live-devel] [live555] about NTP/RTP timestamp for rtcp/rtp packets

[Warren Young]

On Mar 26, 2020, at 3:36 AM, Zhang Qian（张倩） <qianzhang at asrmicro.com> wrote:
> 
> If user modifies the system time for device, seems it will impact A/V sync for client. How can I avoid this problem?

Have your user switch to calling adjtimex(2) instead:

    http://man7.org/linux/man-pages/man2/adjtimex.2.html

Yes, it’s more complicated than doing a blind settimeofday(2) or similar, but it’s more complicated specifically in order to deal with problems like the one you bring up.

Better, stop allowing direct time edits and set up a proper NTP client.  Most of them will use adjtimex(2) or similar APIs unless you configure them not to.

There are a few “simple” NTP clients that do single-step time adjustment; avoid them in this case.