Added a kEchoCancellation constraint to turn off the audio processing.

content/renderer/media/media_stream_audio_processor.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/renderer/media/media_stream_audio_processor.h"
 
 #include "base/command_line.h"
 #include "base/debug/trace_event.h"
 #include "base/metrics/field_trial.h"
 #include "base/metrics/histogram.h"
@@ skipping 262 matching lines @@
   stats->typing_noise_detected =
       (base::subtle::Acquire_Load(&typing_detected_) != false);
   GetAecStats(audio_processing_.get(), stats);
 }
 
 void MediaStreamAudioProcessor::InitializeAudioProcessingModule(
     const blink::WebMediaConstraints& constraints, int effects,
     MediaStreamType type) {
   DCHECK(!audio_processing_);
 
-  RTCMediaConstraints native_constraints(constraints);
-
   // Audio mirroring can be enabled even though audio processing is otherwise
   // disabled.
   audio_mirroring_ = GetPropertyFromConstraints(
-      &native_constraints, webrtc::MediaConstraintsInterface::kAudioMirroring);
+      constraints, kGoogAudioMirroring, effects, type);
 
   if (!IsAudioTrackProcessingEnabled()) {
     RecordProcessingState(AUDIO_PROCESSING_IN_WEBRTC);
     return;
   }
 
-  // Only apply the fixed constraints for gUM of MEDIA_DEVICE_AUDIO_CAPTURE.
-  DCHECK(IsAudioMediaType(type));
-  if (type == MEDIA_DEVICE_AUDIO_CAPTURE)
-    ApplyFixedAudioConstraints(&native_constraints);
-
-  if (effects & media::AudioParameters::ECHO_CANCELLER) {
-    // If platform echo canceller is enabled, disable the software AEC.
-    native_constraints.AddMandatory(
-        MediaConstraintsInterface::kEchoCancellation,
-        MediaConstraintsInterface::kValueFalse, true);
-  }
+  const bool echo_calcellation = GetPropertyFromConstraints(

[perkj_chrome, 2014/04/08 10:28:12]

nit: move to where its used.

[tommi (sloooow) - chröme, 2014/04/08 10:49:30]

echo_cancellation  (not calcellation)

Actually, I'm not sure this is the desired behavior.

We want echo cancellation to be turned on by default.  If this constraint is
missing, the echo_cancellation will be set to false which is incorrect.

[no longer working on chromium, 2014/04/11 08:56:30]

Added code to return immediately when the echo_cancellation is false.

[no longer working on chromium, 2014/04/11 08:56:30]

Done.
echo_cancellation will be true if the constraint is missing. The default value
is specified in
media_stream_audio_processor_options.cc::kDefaultAudioConstraints

+      constraints, kEchoCancellation, effects, type);
 
 #if defined(OS_IOS)
   // On iOS, VPIO provides built-in AEC and AGC.
   const bool enable_aec = false;
   const bool enable_agc = false;
 #else
   const bool enable_aec = GetPropertyFromConstraints(

[tommi (sloooow) - chröme, 2014/04/08 10:49:30]

can you change the name of this variable to e.g. goog_aec or
goog_echo_cancellation to properly distinguish it from the variable above?

Do we actually need to call GetPropertyFromConstraints if echo_cancellation is
false?

It feels like this could be:
const bool enable_aec = echo_cancellation && GetPropertyFromConstraints(...);

[no longer working on chromium, 2014/04/11 08:56:30]

Done.
kGoogEchoCancellation can go away if we don't support disabling AEC while
enabling other components. Otherwise we will have to keep it.
what do you think here?
We can't do this until our client (M*) specify kEchoCancellation to be false in
studio mode, I added a TODO to remind it.

-      &native_constraints, MediaConstraintsInterface::kEchoCancellation);
+      constraints, kGoogEchoCancellation, effects, type);
   const bool enable_agc = GetPropertyFromConstraints(

[tommi (sloooow) - chröme, 2014/04/08 10:49:30]

same here and below.

[no longer working on chromium, 2014/04/11 08:56:30]

Done.

-      &native_constraints, webrtc::MediaConstraintsInterface::kAutoGainControl);
+      constraints, kGoogAutoGainControl, effects, type);
 #endif
 
 #if defined(OS_IOS) || defined(OS_ANDROID)
   const bool enable_experimental_aec = false;
   const bool enable_typing_detection = false;
 #else
   const bool enable_experimental_aec = GetPropertyFromConstraints(
-      &native_constraints,
-      MediaConstraintsInterface::kExperimentalEchoCancellation);
+      constraints, kGoogExperimentalEchoCancellation, effects, type);
   const bool enable_typing_detection = GetPropertyFromConstraints(
-      &native_constraints, MediaConstraintsInterface::kTypingNoiseDetection);
+      constraints, kGoogTypingNoiseDetection, effects, type);
 #endif
 
   const bool enable_ns = GetPropertyFromConstraints(
-      &native_constraints, MediaConstraintsInterface::kNoiseSuppression);
+      constraints, kGoogNoiseSuppression, effects, type);
   const bool enable_experimental_ns = GetPropertyFromConstraints(
-        &native_constraints,
-        MediaConstraintsInterface::kExperimentalNoiseSuppression);
+        constraints, kGoogExperimentalNoiseSuppression, effects, type);
   const bool enable_high_pass_filter = GetPropertyFromConstraints(
-      &native_constraints, MediaConstraintsInterface::kHighpassFilter);
+      constraints, kGoogHighpassFilter, effects, type);
 
-  // Return immediately if no audio processing component is enabled.
-  if (!enable_aec && !enable_experimental_aec && !enable_ns &&
-      !enable_high_pass_filter && !enable_typing_detection && !enable_agc &&
-      !enable_experimental_ns) {
+  // |echo_calcellation| is used as a master control on enabling/disabling

[tommi (sloooow) - chröme, 2014/04/08 10:49:30]

fix typo here as well

[no longer working on chromium, 2014/04/11 08:56:30]

Done.

+  // the audio processing. Another way to disable the audio processing is to
+  // turn off all the goog* constraints explicitly.
+  if (!echo_calcellation ||

[no longer working on chromium, 2014/04/08 10:02:53]

The main change is here, echo_calcellation is true by default, if it is  false,
we turn off the audio processing.

[perkj_chrome, 2014/04/08 10:28:12]

fix name echo_calcellation

[tommi (sloooow) - chröme, 2014/04/08 10:49:30]

I think that we're unnecessarily querying all the properties in the case where
echo_cancellation is false.  However, there's also a bug above which sets
echo_cancellation to false if the constraint is not present.

[no longer working on chromium, 2014/04/11 08:56:30]

Done.

[no longer working on chromium, 2014/04/11 08:56:30]

Done with avoid querying the constraints when echo_cancellation is false.

FYI, the previous code was to avoid duplicating
RecordProcessingState(AUDIO_PROCESSING_DISABLED).

+      (!enable_aec && !enable_experimental_aec && !enable_ns &&
+       !enable_high_pass_filter && !enable_typing_detection &&
+       !enable_agc && !enable_experimental_ns)) {
     RecordProcessingState(AUDIO_PROCESSING_DISABLED);
     return;
   }
 
   // Create and configure the webrtc::AudioProcessing.
   audio_processing_.reset(webrtc::AudioProcessing::Create(0));
 
   // Enable the audio processing components.
   if (enable_aec) {
     EnableEchoCancellation(audio_processing_.get());
@@ skipping 159 matching lines @@
 }
 
 bool MediaStreamAudioProcessor::IsAudioTrackProcessingEnabled() const {
   const std::string group_name =
       base::FieldTrialList::FindFullName("MediaStreamAudioTrackProcessing");
   return group_name == "Enabled" || CommandLine::ForCurrentProcess()->HasSwitch(
       switches::kEnableAudioTrackProcessing);
 }
 
 }  // namespace content