Make AEC3 recover more quickly for lost capture data

webrtc/modules/audio_processing/aec3/render_delay_controller.cc

 /*
  *  Copyright (c) 2017 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 #include "webrtc/modules/audio_processing/aec3/render_delay_controller.h"
@@ skipping 41 matching lines @@
 size_t ComputeNewBufferDelay(size_t current_delay,
                              size_t echo_path_delay_samples) {
   // The below division is not exact and the truncation is intended.
   const int echo_path_delay_blocks = echo_path_delay_samples / kBlockSize;
   constexpr int kDelayHeadroomBlocks = 1;
 
   // Compute the buffer delay increase required to achieve the desired latency.
   size_t new_delay = std::max(echo_path_delay_blocks - kDelayHeadroomBlocks, 0);
 
   // Add hysteresis.
-  if (new_delay == current_delay + 1 || new_delay + 1 == current_delay) {
+  if (new_delay == current_delay + 1) {
     new_delay = current_delay;
   }
 
   return new_delay;
 }
 
 int RenderDelayControllerImpl::instance_count_ = 0;
 
 RenderDelayControllerImpl::RenderDelayControllerImpl(int sample_rate_hz)
     : data_dumper_(
           new ApmDataDumper(rtc::AtomicOps::Increment(&instance_count_))),
       delay_estimator_(data_dumper_.get()) {
   RTC_DCHECK(ValidFullBandRate(sample_rate_hz));
 }
 
 RenderDelayControllerImpl::~RenderDelayControllerImpl() = default;
 
 void RenderDelayControllerImpl::Reset() {
-  delay_ = 0;
+  delay_ = kMinEchoPathDelayBlocks;
   blocks_since_last_delay_estimate_ = 300000;
   echo_path_delay_samples_ = 0;
   align_call_counter_ = 0;
   headroom_samples_ = rtc::Optional<size_t>();
 
   delay_estimator_.Reset();
 }
 
 void RenderDelayControllerImpl::SetDelay(size_t render_delay) {
   if (delay_ != render_delay) {
@@ skipping 40 matching lines @@
   return delay_;
 }
 
 }  // namespace
 
 RenderDelayController* RenderDelayController::Create(int sample_rate_hz) {
   return new RenderDelayControllerImpl(sample_rate_hz);
 }
 
 }  // namespace webrtc