From f4d2bd1a5d2919eb503fe461419b763f67308a99 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sebastian=20Dr=C3=B6ge?= <sebastian@centricular.com>
Date: Thu, 28 Nov 2024 23:11:20 +0200
Subject: [PATCH] webrtcsink: Set caps-change-mode=delayed on encoder
 capsfilter

Otherwise when changing the target caps (e.g. for reducing quality)
there is a race condition between buffers between the converter elements
and renegotiation.

For example, videoconvertscale might've output a 1920x1080 buffer, then
the capsfilter is configured to 1280x720, the buffer arrives in
videorate, videorate notices that renegotiation is pending, tries to
renegotiate and ends up with EMPTY caps because it can only change the
framerate but not the resolution.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-rs/-/merge_requests/1949>
---
 net/webrtc/src/utils.rs | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/webrtc/src/utils.rs b/net/webrtc/src/utils.rs
index 4f9a1e3e..8620d808 100644
--- a/net/webrtc/src/utils.rs
+++ b/net/webrtc/src/utils.rs
@@ -716,6 +716,7 @@ impl Codec {
 
         gst::ElementFactory::make("capsfilter")
             .property("caps", &caps)
+            .property_from_str("caps-change-mode", "delayed")
             .build()
             .with_context(|| "Creating capsfilter caps")
     }