Currently the EncodedChunkMetadata dictionary includes SvcOutputMetadata, which only supports temporal scalability (temporalLayerId).

However, within the Encoded-Transform API, RTCEncodedFrameMetadata includes its own (incompatible) SVC metadata.

Here is a comparison of the two approaches:
https://docs.google.com/presentation/d/1lFAUSvApbBYfBNJH_xcRW0YjD0aF5T1ZqjyyDJMesJw/edit#slide=id.g1a4ac56601a_3_0

Can we define the complete set of SVC metadata in WebCodecs and then have it inherited by Encoded Transform?

Related: w3c/webrtc-encoded-transform#170