Make it possible to change the amplitude of the pulses generated by PulsedNoiseCapturer.

This adds a SetCapturer function to testing::FakeAudioDevice::PulsedNoiseCapturer
that can be used to update the volume of the generated audio mid-call. It also modifies
CreatePulsedNoiseCapturer to use PulsedNoiseCapturer's type directly so that its new
function is visible for the callers.

Bug: webrtc:8666
Change-Id: I47726e242ccf221f5511e2797b2954ce035ba371
Reviewed-on: https://webrtc-review.googlesource.com/34650
Reviewed-by: Patrik Höglund <phoglund@webrtc.org>
Reviewed-by: Danil Chapovalov <danilchap@webrtc.org>
Commit-Queue: Erik Varga <erikvarga@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#21521}

test/fake_audio_device.cc

@@ -15,7 +15,6 @@
 
 #include "common_audio/wav_file.h"
 #include "rtc_base/checks.h"
-#include "rtc_base/random.h"
 #include "system_wrappers/include/event_wrapper.h"
 
 namespace webrtc {
@@ -25,45 +24,6 @@ namespace {
 constexpr int kFrameLengthMs = 10;
 constexpr int kFramesPerSecond = 1000 / kFrameLengthMs;
 
-// Assuming 10ms audio packets..
-class PulsedNoiseCapturer final : public test::FakeAudioDevice::Capturer {
- public:
-  PulsedNoiseCapturer(int16_t max_amplitude, int sampling_frequency_in_hz)
-      : sampling_frequency_in_hz_(sampling_frequency_in_hz),
-        fill_with_zero_(false),
-        random_generator_(1),
-        max_amplitude_(max_amplitude) {
-    RTC_DCHECK_GT(max_amplitude, 0);
-  }
-
-  int SamplingFrequency() const override {
-    return sampling_frequency_in_hz_;
-  }
-
-  bool Capture(rtc::BufferT<int16_t>* buffer) override {
-    fill_with_zero_ = !fill_with_zero_;
-    buffer->SetData(
-        test::FakeAudioDevice::SamplesPerFrame(sampling_frequency_in_hz_),
-        [&](rtc::ArrayView<int16_t> data) {
-      if (fill_with_zero_) {
-        std::fill(data.begin(), data.end(), 0);
-      } else {
-        std::generate(data.begin(), data.end(), [&]() {
-          return random_generator_.Rand(-max_amplitude_, max_amplitude_);
-        });
-      }
-      return data.size();
-    });
-    return true;
-  }
-
- private:
-  int sampling_frequency_in_hz_;
-  bool fill_with_zero_;
-  Random random_generator_;
-  const int16_t max_amplitude_;
-};
-
 class WavFileReader final : public test::FakeAudioDevice::Capturer {
  public:
   WavFileReader(std::string filename, int sampling_frequency_in_hz)
@@ -194,14 +154,53 @@ class DiscardRenderer final : public test::FakeAudioDevice::Renderer {
 }  // namespace
 namespace test {
 
+// Assuming 10ms audio packets.
+FakeAudioDevice::PulsedNoiseCapturer::PulsedNoiseCapturer(
+    int16_t max_amplitude,
+    int sampling_frequency_in_hz)
+    : sampling_frequency_in_hz_(sampling_frequency_in_hz),
+      fill_with_zero_(false),
+      random_generator_(1),
+      max_amplitude_(max_amplitude) {
+  RTC_DCHECK_GT(max_amplitude, 0);
+}
+
+bool FakeAudioDevice::PulsedNoiseCapturer::Capture(
+    rtc::BufferT<int16_t>* buffer) {
+  fill_with_zero_ = !fill_with_zero_;
+  int16_t max_amplitude;
+  {
+    rtc::CritScope cs(&lock_);
+    max_amplitude = max_amplitude_;
+  }
+  buffer->SetData(FakeAudioDevice::SamplesPerFrame(sampling_frequency_in_hz_),
+                  [&](rtc::ArrayView<int16_t> data) {
+                    if (fill_with_zero_) {
+                      std::fill(data.begin(), data.end(), 0);
+                    } else {
+                      std::generate(data.begin(), data.end(), [&]() {
+                        return random_generator_.Rand(-max_amplitude,
+                                                      max_amplitude);
+                      });
+                    }
+                    return data.size();
+                  });
+  return true;
+}
+
+void FakeAudioDevice::PulsedNoiseCapturer::SetMaxAmplitude(int16_t amplitude) {
+  rtc::CritScope cs(&lock_);
+  max_amplitude_ = amplitude;
+}
+
 size_t FakeAudioDevice::SamplesPerFrame(int sampling_frequency_in_hz) {
   return rtc::CheckedDivExact(sampling_frequency_in_hz, kFramesPerSecond);
 }
 
-std::unique_ptr<FakeAudioDevice::Capturer>
-    FakeAudioDevice::CreatePulsedNoiseCapturer(
-        int16_t max_amplitude, int sampling_frequency_in_hz) {
-  return std::unique_ptr<FakeAudioDevice::Capturer>(
+std::unique_ptr<FakeAudioDevice::PulsedNoiseCapturer>
+FakeAudioDevice::CreatePulsedNoiseCapturer(int16_t max_amplitude,
+                                           int sampling_frequency_in_hz) {
+  return std::unique_ptr<FakeAudioDevice::PulsedNoiseCapturer>(
       new PulsedNoiseCapturer(max_amplitude, sampling_frequency_in_hz));
 }
 

test/fake_audio_device.h

@@ -20,6 +20,7 @@
 #include "rtc_base/criticalsection.h"
 #include "rtc_base/event.h"
 #include "rtc_base/platform_thread.h"
+#include "rtc_base/random.h"
 #include "typedefs.h"  // NOLINT(build/include)
 
 namespace webrtc {
@@ -59,6 +60,26 @@ class FakeAudioDevice : public FakeAudioDeviceModule {
     virtual bool Render(rtc::ArrayView<const int16_t> data) = 0;
   };
 
+  // A fake capturer that generates pulses with random samples between
+  // -max_amplitude and +max_amplitude.
+  class PulsedNoiseCapturer final : public Capturer {
+   public:
+    PulsedNoiseCapturer(int16_t max_amplitude, int sampling_frequency_in_hz);
+
+    int SamplingFrequency() const override { return sampling_frequency_in_hz_; }
+
+    bool Capture(rtc::BufferT<int16_t>* buffer) override;
+
+    void SetMaxAmplitude(int16_t amplitude);
+
+   private:
+    int sampling_frequency_in_hz_;
+    bool fill_with_zero_;
+    Random random_generator_;
+    rtc::CriticalSection lock_;
+    int16_t max_amplitude_ RTC_GUARDED_BY(lock_);
+  };
+
   // Creates a new FakeAudioDevice. When capturing or playing, 10 ms audio
   // frames will be processed every 10ms / |speed|.
   // |capturer| is an object that produces audio data. Can be nullptr if this
@@ -74,8 +95,9 @@ class FakeAudioDevice : public FakeAudioDeviceModule {
   // Returns a Capturer instance that generates a signal where every second
   // frame is zero and every second frame is evenly distributed random noise
   // with max amplitude |max_amplitude|.
-  static std::unique_ptr<Capturer> CreatePulsedNoiseCapturer(
-      int16_t max_amplitude, int sampling_frequency_in_hz);
+  static std::unique_ptr<PulsedNoiseCapturer> CreatePulsedNoiseCapturer(
+      int16_t max_amplitude,
+      int sampling_frequency_in_hz);
 
   // Returns a Capturer instance that gets its data from a file.
   static std::unique_ptr<Capturer> CreateWavFileReader(

test/fake_audio_device_unittest.cc

@@ -127,5 +127,31 @@ TEST(BoundedWavFileWriterTest, EndSilenceCutoff) {
   RunTest(kInputSamples, kExpectedSamples, 8);
 }
 
+TEST(PulsedNoiseCapturerTest, SetMaxAmplitude) {
+  const int16_t kAmplitude = 50;
+  std::unique_ptr<FakeAudioDevice::PulsedNoiseCapturer> capturer =
+      FakeAudioDevice::CreatePulsedNoiseCapturer(
+          kAmplitude, /*sampling_frequency_in_hz=*/8000);
+  rtc::BufferT<int16_t> recording_buffer;
+
+  // Verify that the capturer doesn't create entries louder than than
+  // kAmplitude. Since the pulse generator alternates between writing
+  // zeroes and actual entries, we need to do the capturing twice.
+  capturer->Capture(&recording_buffer);
+  capturer->Capture(&recording_buffer);
+  int16_t max_sample =
+      *std::max_element(recording_buffer.begin(), recording_buffer.end());
+  EXPECT_LE(max_sample, kAmplitude);
+
+  // Increase the amplitude and verify that the samples can now be louder
+  // than the previous max.
+  capturer->SetMaxAmplitude(kAmplitude * 2);
+  capturer->Capture(&recording_buffer);
+  capturer->Capture(&recording_buffer);
+  max_sample =
+      *std::max_element(recording_buffer.begin(), recording_buffer.end());
+  EXPECT_GT(max_sample, kAmplitude);
+}
+
 }  // namespace test
 }  // namespace webrtc