The WebRTC getStats API exposes the encoder and decoder implementation
names for outbound and inbound video:

https://w3c.github.io/webrtc-stats/#dom-rtcoutboundrtpstreamstats-encoderimplementation

It will no longer provide the value “unknown” in cases where statistics are
queried before a video frame was encoded or decoded. Instead, the
dictionary member will be omitted which follows the general pattern not to
return meaningless information described in

https://w3c.github.io/webrtc-stats/#guidelines-for-implementing-stats-objects

The stats collector implementation actually checks for the empty string
<https://source.chromium.org/chromium/chromium/src/+/main:third_party/webrtc/pc/rtc_stats_collector.cc;l=822?q=rtc_stats_collector.cc>
but the underlying data source has a default value of "unknown".

Similarly, the datachannel statistics dataChannelIdentifier

https://w3c.github.io/webrtc-stats/#dom-rtcdatachannelstats-datachannelidentifier

is currently being set to -1 before the DTLS connection is established.

This is being guarded against in the “legacy stats
<https://source.chromium.org/chromium/chromium/src/+/main:third_party/webrtc/pc/legacy_stats_collector.cc;l=1312;drc=f9e13f8813ebb6c69cf88aada787336244cf8be9>”
but not the spec stats sadly.

Both properties are not available in Firefox or Safari yet as can be seen
in WPT
<https://wpt.fyi/results/webrtc-stats/supported-stats.html?label=experimental&label=master&aligned>
so applications should be prepared for this already.

For more details see the respectives changes [1
<https://webrtc-review.googlesource.com/c/src/+/293600>, 2
<https://webrtc-review.googlesource.com/c/src/+/300483>] in libwebrtc.

Chromestatus feature links:

https://chromestatus.com/feature/5072770423062528

https://chromestatus.com/feature/5088165401985024

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