Re: [webrtc-encoded-transform] Add description of an API for controlling SDP codec negotiation (#186)

> > 1. Enable media agnostic RTP payload formats like SFrame.
> 
> Do you mean any other types here, or just SFrame? Do you have an example?

You heard the SCIP (NATO) format being mentioned on the call. That's one.
A payload format to replace Google's nonstandard a=packetization-mode:raw would be another.

> 
> > For 1, we assume the UA implements the RTP payload format.
> > setCodecPreferences can be used if the UA does not negotiate it by default.
> 
> What would that look like? Would it multiply the payload types in `RTCRtpSender.getCapabilities("video")`?
> 

It would look like the API described in https://developer.mozilla.org/en-US/docs/Web/API/RTCRtpTransceiver/setCodecPreferences

> > 2. Allow the application to select one of these RTP payload formats as part of a RTCRtpSender transform.
> 
> Do you mean a RTCRtpScriptTransform here? What would that look like?

From the explainer:
```
    metadata = frame.metadata();
    metadata.pt = options.payloadType;
    frame.setMetadata(metadata);
```


> 
> > ```
> > partial interface RTCEncodedVideoFrame {
> >    attribute DOMString rtpPayloadFormat;
> > ```
> 
> What's the advantage or use case for choosing this per frame?
> 

I believe Youenn described this case in details on the call; I added this FAQ question specifically to address his use case.

From the explainer:

1.  Q: My application wants to send frames with multiple packetizers. How do I accomplish that?

    A: Use multiple payload types. Each will be assigned a payload type. Mark each frame with the payload type they need to be packetized as.
 
> Apps can already specify SFrame ahead of negotiation, so doesn't the UA have all it needs to negotiate sframe?

I particularly mentioned on the call (and have said in every presentation that I've given on it) that I want an interface that is able to support the existing, deployed, Javascript-based sframe format, which is not the same as the sframe transform that is supposed to use the (still not final) IETF SFrame format draft, *or any other transform*.
 



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Received on Sunday, 15 October 2023 22:56:34 UTC