This CL partly restores the changes that were introduced in https://webrtc-review.googlesource.com/c/src/+/344681 The predefined SdpVideoFormat for AV1 causes some backwards compatibility issues with downstream projects that are using the preliminary codec name AV1X. Bug: b/333007070 Change-Id: I2d4df241d47b399b0012e6095dd6c2445e60e2c1 Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/345941 Commit-Queue: Johannes Kron <kron@webrtc.org> Reviewed-by: Harald Alvestrand <hta@webrtc.org> Cr-Commit-Position: refs/heads/main@{#42011}