Examples pipe multiple streams into a single writable

[jan-ivar]

The examples won't work as written for more than one sender:

const rtpTransport = pc.createRtpTransport();
pc.getSenders().forEach((sender) => {
  pc.createEncodedStreams().readable.
      pipeThrough(createPacketizingTransformer()).pipeTo(rtpTransport.writable);
});

...because multiple streams cannot be piped into a single writable.

It's not super-clear what a single "transport" is meant to be scoped to.

1. Is there one for the entire peer connection?
2. Is there one per transceiver?
3. Is there one per sender and receiver?
4. Is there one per transform?
5. Can apps create as many as they wish?

Is it just a packetizer sink? — In #14 I end up with number 4.

Conceptually, is this just be some option on a transform to change expected inputs and outputs? E.g. on the sender:

1. encodedFrame → encodedFrame (default, e.g. e2ee)
2. encodedFrame → packet (e.g adding metadata)
3. Frame → encodedFrame (JS encoder)
4. Frame → packet (hold my beer)

If so, this proposal may be closer to @alvestrand's than I previously appreciated.

[aboba]

The example has multiple problems:

• Multiple streams are piped into a single writable.
• The examples uses the legacy accessor API instead of the standardized API.
• The example uses the legacy accessor API incorrectly.

So there is a lot to fix.

[dontcallmedom-bot]

This issue was mentioned in WEBRTCWG-2023-12-05 (Page 62)