commit b1fc54d33e109b9bab10114b3aa0d47eb90b799d
author peah <peah@webrtc.org> Thu May 12 12:08:45 2016
committer Commit bot <commit-bot@chromium.org> Thu May 12 12:08:53 2016
tree ecc3e98dd13f03c8a1e574660047f63f41c6c1db
parent 50b5c3be844ef571a28b2681c549443a26735d72

Corrected the delay agnostic AEC behavior during periods of silent farend signal.
Added conditional updating of the statistics and the delay estimate so that
updates are only done when the farend is non-stationary.

The reason for this is that all the values that go into the updating of the
statistics, and that in turn are also used to update the delay, are frozen
when the farend signal is non-stationary. Therefore, when the farend signal
is silent (stationary), the last estimates present before the silent (stationary)
period began are used to continue to update the statistics. This is a problem as
the updating is done in a manner that assumes that the estimates continue
to be updated.

This CL conditions the updating based on stationarity instead of silence
as both are treated in the same manner in the delay agnostic AEC.
This makes sense theoretically as the delay agnostic AEC operates on
analyzing power deviations (in bands) from a slowly updated average power and
therefore for a stationary signal will have no such deviations to base its analysis
on.

BUG=webrtc:5875, chromium:576624

NOTRY=True

Review-Url: https://codereview.webrtc.org/1967033002
Cr-Commit-Position: refs/heads/master@{#12700}