Improves the capture latency by reducing the amount of
copying needed from the frame. We keep track of the
damaged region of previous frame and union it with
the damaged region of this frame and only copy this
union of the frame over. X11 capturer already has
such synchronization in place.
The change is beneficial especially when there are
small changes on the screen (e.g. clock ticking).
For a 4k screen with 128 cores, I observed the
capture latencies drop from 5 - 8 ms to 0 ms when the
system is left idle. This is in line with the X11
capturer.
Bug: chromium:1291247
Change-Id: Iffb441f9e1902d2658031f5f35b5372ee8e94073
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/299720
Reviewed-by: Alexander Cooper <alcooper@chromium.org>
Commit-Queue: Salman Malik <salmanmalik@chromium.org>
Cr-Commit-Position: refs/heads/main@{#39968}
8856410b6d