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shared_screencast_stream: Allow overwriting next shared frame

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This makes the implementation in line with the existing X11
implementation:

https://source.chromium.org/chromium/chromium/src/+/main:third_party/webrtc/modules/desktop_capture/linux/x11/screen_capturer_x11.cc;l=240-243

The issue I am observing on slightly slower machines with 4k monitor
is that the frames tend to go back in time. I believe this happens
when the shared frame queue is full and has its frame shared. When
that happens, we still end up calling MoveToNextFrame and doing so
we will wrap around the queue and if the capturer captures a frame
again, it sees an older frame. This is causing screen glitches.

This CL normalizes the implementation with X11 (which is known to
work fine) and moves to next frame and always uses it. This helps
to keep the current_frame_ in sync for the caller / capturer and
the capturer will then always see the video moving forward.

On the same machine, these screencasts were taken:
Without this fix: https://youtu.be/7Toi8dL5eYw
With this fix: https://youtu.be/LOE8Si5iOuQ

Bug: chromium:1291247
Change-Id: I51d3d700d3417d31371b12a94f445fc7b530cf73
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/278700
Reviewed-by: Alexander Cooper <alcooper@chromium.org>
Commit-Queue: Salman Malik <salmanmalik@chromium.org>
Cr-Commit-Position: refs/heads/main@{#38342}
This commit is contained in:
Salman Malik
2022-10-10 18:13:02 +00:00
committed by WebRTC LUCI CQ
parent 8d92c04a6d
commit b2ab0d7d04
1 changed files with 2 additions and 7 deletions
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7
modules/desktop_capture/linux/wayland/shared_screencast_stream.cc
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@ -796,14 +796,9 @@ void SharedScreenCastStreamPrivate::ProcessBuffer(pw_buffer* buffer) {
webrtc::MutexLock lock(&queue_lock_);
// Move to the next frame if the current one is being used and shared
if (queue_.current_frame() && queue_.current_frame()->IsShared()) {
queue_.MoveToNextFrame();
if (queue_.current_frame() && queue_.current_frame()->IsShared()) {
RTC_LOG(LS_WARNING)
<< "Failed to process PipeWire buffer: no available frame";
return;
}
RTC_DLOG(LS_WARNING) << "Overwriting frame that is still shared";
}
if (!queue_.current_frame() ||