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openvidu-browser: simulcast default 3 layers and 4:2:1 scaling 

Leaves maxBitrate undefined so the browser chooses which are the best
values.
pull/648/head
Juan Navarro 2021-07-02 15:05:45 +02:00
parent 08b0742163
commit e66c5d1070
1 changed files with 30 additions and 13 deletions
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43
openvidu-browser/src/OpenViduInternal/WebRtcPeer/WebRtcPeer.ts
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@ -47,29 +47,46 @@ let platform: PlatformUtils;
* | 640x360 | 700 | 2 |
* | 480x270 | 450 | 2 |
* | 320x180 | 200 | 1 |
*
* Firefox will send as many layers as we request, but there are some limits on
* their bitrate:
*
* | Size (px) | Min bitrate (bps) | Start bitrate (bps) | Max bitrate (bps) | Comments |
* |----------:|------------------:|--------------------:|------------------:|---------------:|
* | 1920x1200 | 1500 | 2000 | 10000 | >HD (3K, 4K) |
* | 1280x720 | 1200 | 1500 | 5000 | HD ~1080-1200 |
* | 800x480 | 200 | 800 | 2500 | HD ~720 |
* | 480x270 | 150 | 500 | 2000 | WVGA |
* | 400x240 | 125 | 300 | 1300 | VGA |
* | 176x144 | 100 | 150 | 500 | WQVGA, CIF |
* | 0 | 40 | 80 | 250 | QCIF and below |
*
* Docs for `RTCRtpEncodingParameters`: https://www.w3.org/TR/webrtc/#dom-rtcrtpencodingparameters
* Most interesting members are `maxBitrate` and `scaleResolutionDownBy`.
*
* `scaleResolutionDownBy` is specified as 4:2:1 which is the same that the default.
* The WebRTC spec says this (https://www.w3.org/TR/webrtc/#dom-rtcpeerconnection-addtransceiver):
* > If the scaleResolutionDownBy attributes of sendEncodings are still undefined, initialize
* > each encoding's scaleResolutionDownBy to 2^(length of sendEncodings - encoding index
* > - 1). This results in smaller-to-larger resolutions where the last encoding has no scaling
* > applied to it, e.g. 4:2:1 if the length is 3.
* However, Firefox doesn't seem to implement this default yet. Mediasoup never gets to select
* an output layer.
*
* `maxBitrate` is left unspecified, to let the client decide based on its own
* bandwidth limit detection.
*/
const simulcastVideoEncodings: RTCRtpEncodingParameters[] = [
{
rid: "r0",
maxBitrate: 700000,
// TODO: Remove for final version; leave the browser decide:
// https://w3c.github.io/webrtc-pc/#dom-rtcpeerconnection-addtransceiver
// > If the scaleResolutionDownBy attribues of sendEncodings are still
// > undefined, initialize each encoding's scaleResolutionDownBy to
// > 2^(length of sendEncodings - encoding index - 1). This results in
// > smaller-to-larger resolutions where the last encoding has no scaling
// > applied to it, e.g. 4:2:1 if the length is 3.
scaleResolutionDownBy: 16,
scaleResolutionDownBy: 4,
},
{
rid: "r1",
maxBitrate: 800000,
scaleResolutionDownBy: 8,
scaleResolutionDownBy: 2,
},
{
rid: "r2",
maxBitrate: 900000,
scaleResolutionDownBy: 1,
},
];