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Re: [webrtc-stats] RTCMediaStreamTrackStats.audioLevel clarification

From: Harald Alvestrand via GitHub <sysbot+gh@w3.org>
Date: Wed, 25 Oct 2017 12:15:06 +0000
To: public-webrtc-logs@w3.org
Message-ID: <issue_comment.created-339310231-1508933704-sysbot+gh@w3.org>
We have totalAudioEnergy defined now, which is computable. Is it possible to define audioLevel in terms of a computation over totalAudioEnergy?

I worry about audioLevel since it's inherently a "windowing" operator - instantaneous audioLevel doesn't make much sense at all. We could leave it implementation-defined, but that will give implementation variance. https://webrtc.github.io/samples/src/content/getusermedia/volume/ gives a JS implementation that shows two versions of exponential-decay calculation.

"Linear" kind of makes sense if you think that each halving of audio level should represent another 6 dBSPL change (0.25 = -12dB compared to 0 dBov). There are many other curves that could go through the other two defined points (0 dBov and -6 dBov) if the word "linear" is dropped. Suggestions for clearer description?


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