[webrtc-pc] Codec filter in SDP should consider lower level-id as subsets of greater level-id (#3020)

henbos has just created a new issue for https://github.com/w3c/webrtc-pc:

== Codec filter in SDP should consider lower level-id as subsets of greater level-id ==
If you are capable of level-id=X then you are also capable of level-id=Y where Y<X, assuming mimeType and profile is the same. I.e.
- If I can send H265 level-id=180 and receive level-id=156 that means I can sendrecv 156.
- If I can receive H265 level-id=156 and send level-id=180 that means I can sendrecv 156.

Today's filter seems to assume that every unique combination of codec, profile and level-id is included in the list:
> If transceiver.[direction](https://w3c.github.io/webrtc-pc/#dom-rtcrtptransceiver-direction) is "[sendonly](https://w3c.github.io/webrtc-pc/#dom-rtcrtptransceiverdirection-sendonly)" or "[sendrecv](https://w3c.github.io/webrtc-pc/#dom-rtcrtptransceiverdirection-sendrecv)", exclude any codecs not included in the [list of implemented send codecs](https://w3c.github.io/webrtc-pc/#dfn-list-of-implemented-send-codecs) for kind.
>
> If transceiver.[direction](https://w3c.github.io/webrtc-pc/#dom-rtcrtptransceiver-direction) is "[recvonly](https://w3c.github.io/webrtc-pc/#dom-rtcrtptransceiverdirection-recvonly)" or "[sendrecv](https://w3c.github.io/webrtc-pc/#dom-rtcrtptransceiverdirection-sendrecv)", exclude any codecs not included in the [list of implemented receive codecs](https://w3c.github.io/webrtc-pc/#dfn-list-of-implemented-receive-codecs) for kind.

But in reality, user agents only list the highest level-id they support. Such as 180, rather than all possible values between 0 and 180 as separate codec values.

Let's update this filter to use a comparison step as opposed to "not included" match which implies ==

Please view or discuss this issue at https://github.com/w3c/webrtc-pc/issues/3020 using your GitHub account


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Received on Tuesday, 12 November 2024 10:01:05 UTC