Synchronization precision

[Tim Müller]

On Mon, 2019-07-01 at 14:26 -0500, RiccardoCagnasso wrote:

Hi,

> At gstreamer conference 2017, doctor Raghavan gave a presentation
> about his library that allowed to create simple synchronized. During
> his conference he did highlight something that I had encountered
> before: the synchronized playback is not really perfectly accurate.
> 
> There's usually, an random error that is maximum less than a frame.
> This means that "sometimes", usually once in several seconds, a frame
> is rendered slight after or before its counterpart. This seems to
> happen with the same extent whether the two videos are played on the
> same computer or on two distinct connected via ethernet (which makes
> sense, since the delay of ethernet is sub-1ms).
> 
> In practical scenarios, the error is unnoticeable if any kind of
> bezel is involved, e.g. any kind of video wall, but it becomes
> apparent on a continuous screen, e.g. a ledwall. It's also quite easy
> to spot using the "slow motion" feature (120 fps) of any smartphone.
> 
> https://youtu.be/-1EhKn8E5zY here is an example taken from a very big
> videowall.

For what it's worth, Marc Leeman also gave a talk about this at the
GStreamer Conference 2011:

https://gstconf.ubicast.tv/videos/displaying-sychronized-video-2

(Don't remember into how much detail it went in terms of solutions
though, just thought it might be of interest).

Cheers
 Tim
-- 
Tim Müller, Centricular Ltd - http://www.centricular.com