[x265] [PATCH 2 of 3] Implementation for Intra refresh

[Steve Borho]

On 09/28, Deepthi Nandakumar wrote:
> So, why should maxNumReferences be 1 always?

This is how x264 implemented it. As I understand the feature it is
mostly interesting in video-conferencing environments where encoding is
real time and there is no latency (no B frames) so having a single
reference is typical, so the design was simplified for this use case.

Just guesswork on my part, though.

I think it could work with more than one reference, but the current
patch is assuming single reference in at least one place.

> I'm nicely confused by the requirement here. When intra-refresh is enabled
> (even if the user did not call  the API function x265_intra_refresh), all I
> frames are converted to P frames. The responsibility of the API call is
> only to start a mid-GOP refresh. Does this require a no-scenecut, if not,
> what happens when a scenecut is inserted mid-GOP? Trigger a refresh?

Seems to me that scene-cut should be disabled when intra-refresh is
used. since there are no I frames there is no benefit from scene-cut
detection (except perhaps for rate control purposes). Refreshes should
be periodic or performed on request when the remote end decoder detects
problems.

-- 
Steve Borho