The totalInterFrameDelay property of the RTCInboundRtpStreamStats dictionary indicates the total accumulated time between consecutively rendered frames, in seconds. It is recorded after each frame is rendered.
The inter-frame delay variance can be calculated from totalInterFrameDelay, totalSquaredInterFrameDelay , and framesRendered according to the formula: (totalSquaredInterFrameDelay - totalInterFrameDelay^2/ framesRendered)/framesRendered.
Note: The property is undefined for audio streams.
A positive number, in seconds.