PSA: Deprecated "track" and "stream" stats are unshipped in Canary at 50% in M109

[Henrik Boström]

Hello,

As previously announced, in M107 the deprecated stats dictionaries, RTCMediaStreamTrackStats and RTCMediaStreamStats, were prefixed with the id "DEPRECATED_".

Now, in M109, these stats objects are being unshipped behind a flag, currently rolled out to 50% Canary. Apps that still depend on these legacy metrics will need to migrate their parsers to obtain the relevant metrics from the RTCOutboundRtpStreamStats (type: "outbound-rtp") and RTCInboundRtpStreamStats (type: "inbound-rtp") dictionaries instead.

For receiving and sending singlecast this should be straightforward since generally the same "track" metrics are also available in the RTP stats objects. However for sending simulcast, note that one "outbound-rtp" is produced per simulcast layer. Compare this to legacy "track" stats, which aggregated the metrics from all layers. If the app wants aggregated simulcast metrics, the app will need to sum up the metrics from all the relevant "outbound-rtp" stats objects into a single aggregated stats object.

Currently the unshipping of these metrics only affect Canary (M109+). Stay tuned for further announcements about when we'll advance the "unship deprecated stats" experiment to Beta and Stable channels.

The combination of unshipping legacy metrics and less codecs stats in M108 means that the RTCStatsReport is a lot slimmer today. Compare the size of the report in a one-way video-only call in M106 Stable with M109 Canary and you'll notice only 12 stats objects instead of 65, and improvement that scales with meeting size:

[Henrik Boström]

Correction: the "DEPRECATED_" prefix happened in M106, as seen as the screenshot, then the stats IDs were made a lot more compact in M107, also reducing report size.

[Henrik Boström]

In addition to this, [[deprecated]] was just added to the relevant C++ layer classes (CL).

[Henrik Boström]

Courtesy of Philipp Hancke, these legacy metrics are now rendered red in the chrome://webrtc-internals/ page:

As you can see, the relevant metrics and more are already available in outbound-rtp:

And trackIdentifier is available via the mediaSourceId reference.

[Philipp Hancke]

please also note that webrtc-internals no longer shows the statistics in a

  id (type)

fashion but switched to

 type (some information considered useful, id)

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