commit 00f11224fd7289d94785ca92368bf238550842fa
author Harald Alvestrand <hta@webrtc.org> Fri Jul 21 07:23:01 2023
committer WebRTC LUCI CQ <webrtc-scoped@luci-project-accounts.iam.gserviceaccount.com> Sat Jul 22 21:47:08 2023
tree 58a6a0f84f7723553630f5654fa9d7ea8c7d6d7a
parent f58c8181488013a782480be6b9a891fe4fe9f6bb

Remove extra usage of video-content-type header extension

This extension is documented to carry one bit: Screenshare.
It's been used for carrying simulcast layers and experiment IDs.
This CL removes that usage.

Bug: webrtc:15383
Change-Id: I048b283cde59bf1f607d8abdd53ced07a7add6f8
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/312420
Commit-Queue: Harald Alvestrand <hta@webrtc.org>
Reviewed-by: Ilya Nikolaevskiy <ilnik@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#40457}

modules/rtp_rtcp/source/rtp_header_extensions.cc

diff --git a/modules/rtp_rtcp/source/rtp_header_extensions.cc b/modules/rtp_rtcp/source/rtp_header_extensions.cc
index 81961c6..75e3e3c 100644
--- a/modules/rtp_rtcp/source/rtp_header_extensions.cc
+++ b/modules/rtp_rtcp/source/rtp_header_extensions.cc
@@ -462,7 +462,11 @@
                                       VideoContentType* content_type) {
   if (data.size() == 1 &&
       videocontenttypehelpers::IsValidContentType(data[0])) {
-    *content_type = static_cast<VideoContentType>(data[0]);
+    // Only the lowest bit of ContentType has a defined meaning.
+    // Due to previous, now removed, usage of 5 more bits, values with
+    // those bits set are accepted as valid, but we mask them out before
+    // converting to a VideoContentType.
+    *content_type = static_cast<VideoContentType>(data[0] & 0x1);
     return true;
   }
   return false;