commit f4e99dba4190066880848acad1e0216c98d4ef9f
author Christian Schuldt <cschuldt@webrtc.org> Thu Mar 01 11:32:50 2018 +0100
committer Commit Bot <commit-bot@chromium.org> Thu Mar 01 11:21:12 2018 +0000
tree a40e985297d423047ef2664fb43519566ba688fc
parent b12e434d4cce7c79a457b0d898035ea0e3bd04ae

Update AEC3 echo tail estimation.

Note: estimation is turned OFF if config_.ep_strength.default_len
is set >= 0 (in this case config_.ep_strength.default_len defines a
constant echo decay factor), and hence turned ON if < 0. In case the
echo tail estimation is turned ON, -config_.ep_strength.default_len is
the starting point for the estimator.

The estimation is done in two passes; first we go through all "sections"
(corresponding to chunks of length kFftLengthBy2) of the filter impulse
response to determine which sections correspond to a "stable" decay",
and then the second pass we go through each stable decay section and
estimate the decay. The actual decay estimation is based on linear
regression of the log magnitude of the squared impulse response.
A bunch of sanity checks are also performed continuously to avoid
estimation error during e.g., filter adaptation.

Bug: webrtc:8924
Change-Id: I686ce3f3e8b6b472348f8d6e01fb44c31e25145d
Reviewed-on: https://webrtc-review.googlesource.com/48440
Commit-Queue: Christian Schuldt <cschuldt@webrtc.org>
Reviewed-by: Per Åhgren <peah@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#22247}