Field trial support to whenever possible turn off the AGC and HPF

webrtc/media/engine/webrtcvoiceengine.cc

 /*
  *  Copyright (c) 2004 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.
  */
 
@@ skipping 318 matching lines @@
     const AudioOptions& options) {
   RTC_DCHECK(worker_thread_checker_.CalledOnValidThread());
   return new WebRtcVoiceMediaChannel(this, config, options, call);
 }
 
 bool WebRtcVoiceEngine::ApplyOptions(const AudioOptions& options_in) {
   RTC_DCHECK(worker_thread_checker_.CalledOnValidThread());
   LOG(LS_INFO) << "WebRtcVoiceEngine::ApplyOptions: " << options_in.ToString();
   AudioOptions options = options_in;  // The options are modified below.
 
+  // Set and adjust echo canceller options.
   // kEcConference is AEC with high suppression.
   webrtc::EcModes ec_mode = webrtc::kEcConference;
   if (options.aecm_generate_comfort_noise) {
     LOG(LS_VERBOSE) << "Comfort noise explicitly set to "
                     << *options.aecm_generate_comfort_noise
                     << " (default is false).";
   }
 
 #if defined(WEBRTC_IOS)
-  // On iOS, VPIO provides built-in EC, NS and AGC.
+  // On iOS, VPIO provides built-in EC.
   options.echo_cancellation = rtc::Optional<bool>(false);
-  options.auto_gain_control = rtc::Optional<bool>(false);
-  options.noise_suppression = rtc::Optional<bool>(false);
-  LOG(LS_INFO)
-      << "Always disable AEC, NS and AGC on iOS. Use built-in instead.";
+  options.extended_filter_aec = rtc::Optional<bool>(false);
+  LOG(LS_INFO) << "Always disable AEC on iOS. Use built-in instead.";
 #elif defined(ANDROID)
   ec_mode = webrtc::kEcAecm;
-#endif
-
-#if defined(WEBRTC_IOS) || defined(ANDROID)
-  options.typing_detection = rtc::Optional<bool>(false);
-  options.experimental_agc = rtc::Optional<bool>(false);
   options.extended_filter_aec = rtc::Optional<bool>(false);
-  options.experimental_ns = rtc::Optional<bool>(false);
 #endif
 
   // Delay Agnostic AEC automatically turns on EC if not set except on iOS
   // where the feature is not supported.
   bool use_delay_agnostic_aec = false;
 #if !defined(WEBRTC_IOS)
   if (options.delay_agnostic_aec) {
     use_delay_agnostic_aec = *options.delay_agnostic_aec;
     if (use_delay_agnostic_aec) {
       options.echo_cancellation = rtc::Optional<bool>(true);
       options.extended_filter_aec = rtc::Optional<bool>(true);
       ec_mode = webrtc::kEcConference;
     }
   }
 #endif
 
+// Set and adjust noise suppressor options.

[henrika_webrtc, 2017/05/12 09:27:31]

It is not clear to me what you change here. Is it more than only things based on
the field-trial flag?

[peah-webrtc, 2017/05/12 09:54:07]

The actual changes related to the field trial are present on lines 394-407.

The rest of the changes are re-arranging the hardcoded effects for the Android
and iOS platforms by the effect applied.
That part is not necessary for this code, but as the changes in this CL adds
further platform specific behavior I was concerned that just adding that to the
former code would cause it to be more messy.

One example is the AEC settings:
Before the change:
-Line 349 turns off the AEC for IOS
-Line 355 hardcodes AECM to be used for Android.
-Line 361 turns off the extended filter AEC for IOS and Android
-Line 373 turns on the extended filter if delay agnostic AEC is used and the
platform is not IOS.

That is a lot of logic which is bundled with a lot of platform specific logic
for setting the NS and AGC effects. As the new code on 394-406 affects all of
the set AEC, NS, AGC settings, I thought it made sense to make the preceeding
logic more clear.

Please let me know if you think those changes make sense, otherwise I'd be happy
to revert them.

[henrika_webrtc, 2017/05/17 07:32:59]

The new code looks less bad ;-)

[peah-webrtc, 2017/05/22 21:47:19]

:-) That is a step in the right direction. 

+#if defined(WEBRTC_IOS)
+  // On iOS, VPIO provides built-in NS.
+  options.noise_suppression = rtc::Optional<bool>(false);
+  options.typing_detection = rtc::Optional<bool>(false);
+  options.experimental_ns = rtc::Optional<bool>(false);
+  LOG(LS_INFO) << "Always disable NS on iOS. Use built-in instead.";
+#elif defined(ANDROID)
+  options.typing_detection = rtc::Optional<bool>(false);
+  options.experimental_ns = rtc::Optional<bool>(false);
+#endif
+
+// Set and adjust gain control options.
+#if defined(WEBRTC_IOS)
+  // On iOS, VPIO provides built-in AGC.
+  options.auto_gain_control = rtc::Optional<bool>(false);
+  options.experimental_agc = rtc::Optional<bool>(false);
+  LOG(LS_INFO) << "Always disable AGC on iOS. Use built-in instead.";
+#elif defined(ANDROID)
+  options.experimental_agc = rtc::Optional<bool>(false);
+#endif
+
+#if defined(WEBRTC_IOS) || defined(WEBRTC_ANDROID)

[henrika_webrtc, 2017/05/12 12:20:47]

Please add some comments here about what you intend to test using this field
trial. And add link to bug as well.

[peah-webrtc, 2017/05/22 21:47:19]

Done.

+  // Turn off the gain control if specified by the field trial.
+  if (webrtc::field_trial::IsEnabled(
+          "WebRTC-Audio-MinimizeResamplingOnMobile")) {
+    options.auto_gain_control = rtc::Optional<bool>(false);
+    LOG(LS_INFO) << "Disable AGC according to field trial.";
+    if (!(options.noise_suppression.value_or(false) or
+          options.echo_cancellation.value_or(false))) {
+      // If possible, turn off the high-pass filter.
+      LOG(LS_INFO) << "Disable high-pass filter in response to field trial.";
+      options.highpass_filter = rtc::Optional<bool>(false);
+    }
+  }
+#endif
+
 #if (WEBRTC_INTELLIGIBILITY_ENHANCER == 0)
   // Hardcode the intelligibility enhancer to be off.
   options.intelligibility_enhancer = rtc::Optional<bool>(false);
 #endif
 
   if (options.echo_cancellation) {
     // Check if platform supports built-in EC. Currently only supported on
     // Android and in combination with Java based audio layer.
     // TODO(henrika): investigate possibility to support built-in EC also
     // in combination with Open SL ES audio.
@@ skipping 1938 matching lines @@
                       ssrc);
   if (it != unsignaled_recv_ssrcs_.end()) {
     unsignaled_recv_ssrcs_.erase(it);
     return true;
   }
   return false;
 }
 }  // namespace cricket
 
 #endif  // HAVE_WEBRTC_VOICE