Intent to Implement & Ship: RTCRtpTransceiver.stop()

[Henrik Boström]

Contact emails

gui...@chromium.org, hb...@chromium.org

Spec

https://w3c.github.io/webrtc-pc/#dom-rtcrtptransceiver-stop

Summary

Transceivers allow the sending and/or receiving of media in WebRTC. These are negotiated with SDP, and once negotiated a port is allocated for the transceiver. Stopping a transceiver makes it permanently inactive, which means the port is freed.

Motivation

Stopping a transceiver releases the network port and allows the browser to release any encoder or decoder resources. It also allows recycling m= section in the SDP so that future transceivers (future media) can be negotiated over this session without the list of m= section growing indefinitely. This API is important to reduce resources used by transceivers and to limit the amount of bloat signaled in the SDP, which is important when you have a large number of them in a session. Use cases: large video conference or long-lasting sessions where media is repeatedly added and removed.

Risks

Interoperability and Compatibility

Low, this is already shipped in Firefox and Safari and all major browsers have positive signals towards it.

Ergonomics

"Could the default usage of this API make it hard for Chrome to maintain good performance?" No, but *not* supporting it could lead to performance issues; if thousands of transceivers are allocated but never stopped this could lead to OOM crashes unless special optimization logic is implemented.

Activation

N/A

Will this feature be supported on all six Blink platforms (Windows, Mac, Linux, Chrome OS, Android, and Android WebView)?

Yes.

Link to entry on the feature dashboard

https://www.chromestatus.com/feature/5410592384876544

Requesting approval to ship?

Yes.

[Yoav Weiss]

LGTM1

I'm assuming there's a WPT suite for the feature. Is that assumption correct?

 

Link to entry on the feature dashboard

https://www.chromestatus.com/feature/5410592384876544

Requesting approval to ship?

Yes.

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[Guido Urdaneta]

Yes, there is a WPT suite. See 

https://cs.chromium.org/chromium/src/third_party/blink/web_tests/external/wpt/webrtc/, specifically  

https://cs.chromium.org/chromium/src/third_party/blink/web_tests/external/wpt/webrtc/RTCRtpTransceiver-stop.html

[Alex Russell]

LGTM2

LGTM1

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[Chris Harrelson]

LGTM3

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[Philip Jägenstedt]

LGTM3, thanks for closing the gap to what's already shipped in other browsers!

I see in https://wpt.fyi/results/webrtc/RTCRtpTransceiver-stop.html?run_id=6249223892762624&run_id=5147192360697856&run_id=4847630303625216&run_id=5169585615536128 that one test is failing in Firefox. Can you look into that if it ends up passing on Chrome?

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[Boris Zbarsky]

On 4/11/19 3:21 PM, Philip Jägenstedt wrote:
> I see in
> https://wpt.fyi/results/webrtc/RTCRtpTransceiver-stop.html?run_id=6249223892762624&run_id=5147192360697856&run_id=4847630303625216&run_id=5169585615536128 that
> one test is failing in Firefox. Can you look into that if it ends up
> passing on Chrome?

Note that as far as we can tell this test is buggy. See
https://bugzilla.mozilla.org/show_bug.cgi?id=1531914 which has a change
to the test waiting for review.

It might be good to figure out whether that diagnosis is correct (and it
seems plausible to me, given the mismatch between the test's description
and what it's actually testing) and if so why Safari is passing it...

-Boris

[Harald Alvestrand]

FYI (resurrecting a very old thread):
I've finally gotten around to finishing this implementation. It is available as an experimental feature (behind a flag) in M86; I intend to enable it by default in M87.