1481725 - re-evaluate minimum bitrate for 640xsomething resolution

Status: RESOLVED FIXED

(Core :: WebRTC: Audio/Video, defect, P2)

Description

[Philipp Hancke [:fippo]]

Attachment: 125kbps bitrate limit in firefox nightly

followup on https://bugzilla.mozilla.org/show_bug.cgi?id=1474661#c22

I think the minimum bitrate should not be 300kbps but 150kbps, same as in webrtc.org. Otherwise there is a gap between the maximum bitrate the 320x180 layer is going to send (150kbps) and where the 640x360 layer starts encoding.
And the maximum REMB estimate one can get from these 150kbps is around 260kbps which means one can get "stuck" in the low-resolution layer.

From what I can see this does not seem to affect non-simulcast streams, https://webrtc.github.io/samples/src/content/peerconnection/bandwidth/ works fine (when modified to use 640x360) even at 125kbps.

Comment 1

[Philipp Hancke [:fippo]]

Attachment: minbitrate.patch

Comment 2

[Byron Campen [:bwc]]

Comment on attachment 8998454 [details] [diff] [review]
minbitrate.patch

Review of attachment 8998454 [details] [diff] [review]:
-----------------------------------------------------------------

::: media/webrtc/signaling/src/media-conduit/VideoConduit.cpp
@@ +1634,1 @@
>    {tl::Max<MB_OF(400, 240), MB_OF(352, 288)>::value, KBPS(200), KBPS(300), KBPS(1300)}, // VGA, WVGA

The min for 480x270 is lower than the min for the next resolution down.

Comment 3

[Philipp Hancke [:fippo]]

Attachment: minbitrate2.patch

also moved the WVGA a bit. Not sure if 125k is a good minimum bitrate but afaics the min bitrate seems unused for non-simulcast. Maybe it is only used with googSuspendBelowMinBitrate as described in http://www.rtcbits.com/2016/11/controlling-bandwidth-usage-in-webrtc.html ?

Comment 4

[Byron Campen [:bwc]]

Comment on attachment 8998779 [details] [diff] [review]
minbitrate2.patch

Review of attachment 8998779 [details] [diff] [review]:
-----------------------------------------------------------------

This seems to work ok.

Comment 5

[Philipp Hancke [:fippo]]

bwc: can you help me land that please?

Comment 6

[Byron Campen [:bwc]]

https://treeherder.mozilla.org/#/jobs?repo=try&revision=e31b37f92ce1d757c11cc13bc8fdeb69129b886e

Comment 7

[Byron Campen [:bwc]]

https://treeherder.mozilla.org/#/jobs?repo=try&revision=239d1633e48c6ee2a509c0edfea96d8f95cd022c

Comment 8

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/dc2b23ed78c7
change minimum bitrate for VGA to 150kbps r=bwc

Comment 9

[Cosmin Sabou [:CosminS]]

https://hg.mozilla.org/mozilla-central/rev/dc2b23ed78c7