echoReturnLoss

media-sourceoutboundaudio

ERL value for a microphone where echo cancellation is applied.

Description

Real number; in decibels

MUST NOT exist for video (this is audio only).

Only exists when the MediaStreamTrack is sourced from a microphone where echo cancellation is applied.

If multiple audio channels are used, the channel of the least audio energy is considered for any sample.

The calculation taken here is defined in G.168 section 3.14:

  • The attenuation of a signal from the receive-out port (Rout) to the send-in port (Sin) of an echo canceller, due to transmission and hybrid loss, i.e., the loss in the (cancelled-end) echo path
  • NOTE – ERL is not the same as echo loss defined in clause 2.2 of [ITU-T G.122] since echo loss is a weighted integral of the loss/frequency function over the band 300-3400 Hz, and so has a fixed value for any particular echo path characteristic
  • Also, echo loss applies to loss of the a-t-b path viewed from the virtual switching point of the international circuit
  • The echo canceller may be located closer to the echo reflection point

See also