Add default values and a static Create() function that determines the parameters to use based on the specified codec and potential field trial overrides. Bug: chromium:328598314 Change-Id: I7a9331a1fd0ed4bd258788760592ea84e535e43b Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/355903 Reviewed-by: Ilya Nikolaevskiy <ilnik@webrtc.org> Reviewed-by: Markus Handell <handellm@google.com> Commit-Queue: Johannes Kron <kron@webrtc.org> Cr-Commit-Position: refs/heads/main@{#42567}