Re: Reusing a transceiver to send a new track with different encodings (WANNA DIE)

> On 28 Jan 2019, at 16:29, Iñaki Baz Castillo <ibc@aliax.net> wrote:
> 
> Hi,
> 
> It seems that reusing a transceiver is a pain. Use case:
> 
> 1) Create a transceiver for sending video.
> 
> 2) Pass 3 encodings in the `addTransceiver()` call or later in
> `transceiver.sender.setParameters()`.
> 
> 3) Later "stop" the sender by stopping the track and calling
> transceiver.sender.replaceTrack(null) and transceiver.direction =
> "inactive".
> 
> 4) Reuse the transceiver to send a new video, now without simulcast.
> Do it via transceiver.sender.replaceTrack(newTrack),
> transceiver.direction = "sendonly" and
> transceiver.sender.setParameters(newEncodings), where `newEncodings`
> is an array with just one encoding (no simulcast desired).
> 
> According to the spec [*] this is not valid:
> 
> [*] https://www.w3.org/TR/webrtc/#dom-rtcrtpsender-setparameters
> 
>> 6.3 Let N be the number of RTCRtpEncodingParameters stored in sender's internal
>>      [[SendEncodings]] slot.
>>      If any of the following conditions are met, return a promise rejected with a newly
>>      createdInvalidModificationError:
>> 
>> 6.4 encodings.length is different from N.  <==== THIS
> 
> 
> So reusing a transceiver is just a pain because having to reuse
> previous encodings is not friendly at all.
> 
> Yes, of course, I could initially set 20 encodings and set
> active=false in most of them, so later I can switch them on/off
> individually to get the "desired" behavior. No. This is a pint.
> 
> 
> Can we please move to WebRTC 2.0 and get rid of SDP semantics and
> artificial limitations due to the nature of SDP?

+1 
I’ve just wasted a morning trying to upgrade a recvonly audio connection to a sendrcv one
using transceivers - Not being ‘Unified Plan’ it doesn’t work.

So, guess what, I’m munging the SDP and _locally_ faking an offer-answer exchange.

T

> 
> 
> -- 
> Iñaki Baz Castillo
> <ibc@aliax.net>
>

Received on Monday, 28 January 2019 17:20:06 UTC