WebRTC 1.0 Improvements and testing


  • Goals
    • Improve browsers support for Simulcast 1.0,
      • evaluated by the number of passing compliance tests,
    • interoperate better with other browser,
    • and for simulcast 1.0 specifically with SFUs
      • evaluated by the number of passing KITE tests.
    • Evaluate tests Scenario for the SVC spec and for AV1
    • Enable H.265 HW acceleration in libwebrtc.
  • Champion(s)
    • Harald Alvestrand <harald at>,
    • "Dr Alex" Gouaillard <alex.gouaillard at>
  • Browser vendors with Staff on site to fix on-the-fly
    • Google (Harald, ... )
    • Apple (Youenn F.)
    • Mozilla (Nils O., ...) TBC
    • Microsoft (Bernard A., ...) TBC
  • SFU Vendors with staff on site to fix on-the-fly
    • Janus (lorenzo)
    • Jitsi (Jonathan is on-site but might not be always at the webrtc table, see RMCAT proposal) TBC
    • meedoze (Sergio)
    • INTEL OpenWebRTC and Visual Cloud (Lai)
    • others ?
  • Project(s)
    • Simulcast and WEBRTC 1.0 tests
      • Add more tests to the Web Platform Tests suite for webrtc 1.0 Simulcast API Compliance
      • Add more tests to the KITE webrtc 1.0 simulcast interop test suite
      • Specifically Test browser interoperability with SFUs and MCUs in Simulcast Mode
      • FIx browsers, rince, repeat
      • fix SFUs, rince repeat
    • AV1 in WebRTC
      • update for those interested
      • Testing scenarios and test beds proposal
    • H.265 hardware acceleration in libwebrtc m78+
      • Bring in INTEL implementation,
      • Write enough unit test to make it acceptable by google upstream
      • Add support for MacOS
      • Prepare a webkit version and test it with safari
      • do interop testing,
        • android, iOS, macOS, win
        • p2p with appRTC / PeerConnection? Client ?
        • with SFU/MCU using INTEL's
    • RMCAT: new BWE/CC in jitsi

KITE Test Bed for all

Specifically for this event, we created a gitHub repository with two automated kite interoperability tests.

One test is a "typical" SFU test: KITE-Janus-Test is provided, which can be easily adapted to test any SFU, and should be the starting point for SFU developers wanting to automatically test against all the browser configuration CoSMo will provide for testing that week end.

SFU Tests

CoSMo's Meedoze - The reference implementation to test Simulcast Again

One test, "KITE-Simulcast-Test", was specifically developed to test browser compliance. An app which sends simulcast to a special SFU based on meedoze, and receives back a given stream back depending on interaction with the UI is provided. It allows to test in loopback mode with a single browser (since simulcast is only sender side anyway), and all stream selection logic is made through UI button which makes it easily instrumented through KITE. The different simulcast features are not tested directly but indirectly (if I can select and receive a stream at a specific configuration it means the SFU receives them well and can differentiate them). The medooze simulcast loopback page, used by e.g. Apple for testing is hosted here:

Meetecho's Janus

There are a couple of demo pages available:

By default, no simulcast is used. To use simulcast, you need to add a query string attribute to those urls:

  • ?simulcast=true enables simulcast via SDP munging
  • ?simulcast2=true enables rid-based simulcast (Chrome only)
  • ?vcodec=h264 tries to force H.264 instead of the default (vp8)

For Firefox, always use the first one (will use rid but using the legacy API).

Lorenzo will be in the room and host a local Janus instance for testing as well: easier to tweak and update when doing interoperability testing.


Even if not attending, Inaki, tech lead of media soup, prepared some test for us.

To test Mediasoup, one can use

Some global variables in the browser console for debugging:

  • PC1: the Peer Connection that sends mic/webcam.
  • PC2: the Peer Connection that receives remote audio/video tracks using BUNDLE.
  • CLIENT._micProducer and CLIENT._webcamProducer: mediasoup Producers, useful to check their rtpParameteres that have been signaled to the SFU.
  • sendSdps(): prints the local and remote SDP of the sending Peer Connection (PC1).
  • recvSdps(): prints the local and remote SDP of the sending Peer Connection (PC2).

8x8's Jitsi Media server

Jonathan Lennox has been working on modifying the Jitsi Videobridge to make it easy to adapt it for alternate bandwidth estimation algorithms, hoping it could be a good environment to make running-code RMCAT testing and comparisons possible. The API he's created is hopefully clean and simple, modelled on the one in the ns3-rmcat repo with some changes. The code is written in Kotlin, so Kotlin and Java should work with it immediately, and native (C or C++) should be able to work through JNI. The interface can be seen at

Interesting links and prerequisite reading

Last modified 3 months ago Last modified on Oct 29, 2019, 2:20:49 PM