WebRTC 1.0 Interoperability Tests Results

Summary - December 2020

Every feature not marked at risk of the WebRTC 1.0 specification has been demonstrably and independently implemented in two browsers, except for:

• A few mandatory-to-implement stats which have not been implemented, but are not critical to real-world interoperability and which implementors are committed to provide in the upcoming weeks.
• The RTCSctpTransport and RTCIceTransport interfaces have been implemented in only one current browser; other browser vendors have indicated their intent to eventually ship these, and these interfaces have also received implementation experience outside of current browsers (in the old Edge Spartan, in orclib, in the Medooze server).
• RTCRtpSender.setStreams() is implemented in a single browser, but is expected to land in more browsers in the near future.
• The closing event for RTCDataChannel is implemented in only one browser, but is expected to land in more browsers in the near future.
• The way browsers report errors occuring during WebRTC operations is not yet fully conformant with the specification.

Given the implementors commitment for these features and given their relative low real-world interoperability impact, the Working Group is confident that these implementation gaps are unlikely to require substantive changes to the specification as implementations catch up. Should this prove necessary, the Working Group will take advantage of the 2020 W3C Process for normative correction of bugs.

As a result of this implementation analysis, the WebRTC Working Group estimates that the implementations of the current WebRTC 1.0 are sufficient to proceed with publication as a W3C Recommendation under the 2020 W3C Process.

Detailed Implementation issues

Gaps

No implementation

voiceActivityFlag in SSRC (marked "at risk")

No implementation (CR, FF)

MTI Stats (CR, full support planned in Safari)

No implementation of

• RTCReceivedRtpStreamStats's packetsDiscarded (CR, FF),
• RTCInboundRtpStreamStats's receiverId,
• RTCOutboundRtpStreamStats's senderId,
• RTCMediaHandlerStats's trackIdentifier,
• RTCIceCandidateStats's url (CR, FF),

Only one implementation

RTCDataChannel.onclosing

Missing in FF (low difficulty) & planned in Safari (webkit)

RTCRtpSender.setStreams()

Not implemented in FF (low difficulty), planned in Safari

RTCDtlsTransport.getRemoteCertificates

Missing from FF impl of RTCDtlsTransport; Safari doesn't implement RTCDtlsTransport

RTCIceTransport interface

Missing in FF; Available in SecureContext only in Chromium? missing component attribute in Chromium; missing most attributes/methods in Safari

onicecandidateerror

Not available in Firefox, Safari

sctp transport

Missing in FF, Safari

RTCError, RTCErrorEvent

Not implemented in Firefox, No plan for Safari (OperationError fallback test?); bug in RTCErrorEvent constructor (cf idlharness test)

RTCPeerConnectionIceEvent url attribute

Missing in FF, Chromium

validation of rid values in addTransceiver

Missing in FF, planned in Safari

RTCPeerConnectionIceErrorEvent

Missing in FF, Safari; address, port missing in Chromium

MTI Stats (single impl)

Full support planned in Safari, Currently only one implementation of RTCReceivedRtpStreamStats's framesDropped, RTCInboundRtpStreamStats's remoteId, RTCInboundRtpStreamStats's framesReceived, RTCInboundRtpStreamStats's totalAudioEnergy,RTCInboundRtpStreamStats's totalSamplesDuration,RTCOutboundRtpStreamStats's framesSent, RTCRemoteOutboundRtpStreamStats's localId, RTCRemoteOutboundRtpStreamStats's remoteTimestamp, RTCPeerConnectionStats's dataChannelsOpened, RTCPeerConnectionStats's dataChannelsClosed, RTCAudioSourceStats's totalAudioEnergy, RTCAudioSourceStats's totalSamplesDuration, RTCVideoSourceStats's width, RTCVideoSourceStats's height, RTCVideoSourceStats's framesPerSecond, RTCTransportStats's bytesSent, RTCTransportStats's bytesReceived, RTCTransportStats's selectedCandidatePairId, RTCTransportStats's localCertificateId, RTCTransportStats's remoteCertificateId, RTCIceCandidateStats's address

Gap in single browser that affect test suite because of dependencies

blob argument for RTCDataChannel.send()

Missing in Chromium (CR2276)

setConfiguration

Missing in Firefox

Bugs

Stats lifecycle

Chromium lifecyle for presence of RTCInboundRtpStreamStats, RTCRemoteInboundRtpStreamStats, RTCOutboundRtpStreamStats, RTCRemoteOutboundRtpStreamStats, RTCDataChannelStats?
FF lifecycle for presence of RTCIceCandidatePairStats.state, currentRoundTripTime. RTCCodecStats, RTCInboundRtpStreamStats, RTCRemoteInboundRtpStreamStats, RTCOutboundRtpStreamStats, RTCRemoteOutboundRtpStreamStats, RTCDataChannelStats, RTCMediaHandlerStats, RTCTransportStats, RTCCertificateStats?

RTCPeerConnection.addIceCandidate()

Supports for zero-argument in Safari

RTCPeerConnection.setLocalDescription()

Supports for zero-argument in Safari

readonly attributes in RTCSessionDescription (type, sdp)

writable in FF, Chromium

restartIce survives remote offer containing partial restart

Not implemented in FF, Chromium

createOffer

Chromium Safari fails "When media stream is added when createOffer() is running in parallel, the result offer should contain the new media stream"

setLocalDescription() with offer not created by own createOffer() should reject with InvalidModificationError

Fails in Chromium, Safari

getSynchronizationSources

returns empty array on audio track in Chromium (?); misses rtpTimestamp, voiceActivityFlag in Safari; doesn't work on video track in FF, which also lacks voiceActivityFlag

mute/unmute timing

Buggy in Chrome, Safari

Test suite issues

Bugs

• In general, some tests are https-only, but not clear if this is always justified
• test for bufferedAmount depends on blob sending (but not implemented in Chromium yet)

Annotated WPT results

MTI Stats

Static results as of 30 september 2020 (based on mandatory stats test)