commit 906f4030882ad6b7f31658e43a15e6165f3431d0
author peah <peah@webrtc.org> Thu Sep 08 16:49:42 2016
committer Commit bot <commit-bot@chromium.org> Thu Sep 08 16:49:50 2016
tree 003903b22c884acd1e6663e1cb97c361b2bc994b
parent 0e62f2bebeb09f4c952009922a7ce46b63db8648

This CL refactors the buffering of the incoming near-end signal inside
the AEC. This solves the following issues:
-Even though the buffering was previously done using ringbuffers, those
  were inefficiently used which caused a lot of hidden memcopys.
-The ringbuffers wasted a lot of space in the AEC state as they were too
  long.
-The lowest and two upper bands were decoupled in the buffering, which
  required extra code to handle.
-On top of the ringbuffers there was a second linear buffer that was
  stored in the state which caused even more data to be stored on the
  state.
-The incoming nearend frames were passed to the functions in the form
  of buffers on the state, which made the code harder to read as it was
  not immediately clear where the nearend signal was used, and when it
  was modified.

The CL addresses this by replacing all the buffers by two linear buffers:
-One buffer before the AEC processing for producing nearend
  blocks of size 64 that can be processed by the AEC.
-One inside the AEC processing that buffers the current
  nearend block until the next block is processed.

The changes have been tested to be bitexact.
This CL will be followed by several other CLs, that refactor the other
buffers in the AEC.

BUG=webrtc:5298, webrtc:6018

Review-Url: https://codereview.webrtc.org/2311833002
Cr-Commit-Position: refs/heads/master@{#14141}