Introduce AudioOutputResampler for browser side resampling.

media/base/multi_channel_resampler_unittest.cc

 // Copyright (c) 2012 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 <cmath>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 30 matching lines @@
   virtual ~MultiChannelResamplerTest() {}
 
   void InitializeAudioData(int channels, int frames) {
     frames_ = frames;
     audio_bus_ = AudioBus::Create(channels, frames);
   }
 
   // MultiChannelResampler::MultiChannelAudioSourceProvider implementation, just
   // fills the provided audio_data with |kFillValue|.
   virtual void ProvideInput(AudioBus* audio_bus) {
+    float fill_value = fill_junk_values_ ? (1 / kFillValue) : kFillValue;
     EXPECT_EQ(audio_bus->channels(), audio_bus_->channels());
     for (int i = 0; i < audio_bus->channels(); ++i)
       for (int j = 0; j < audio_bus->frames(); ++j)
-        audio_bus->channel(i)[j] = kFillValue;
+        audio_bus->channel(i)[j] = fill_value;
   }
 
   void MultiChannelTest(int channels, int frames, double expected_max_rms_error,
                         double expected_max_error) {
     InitializeAudioData(channels, frames);
     MultiChannelResampler resampler(
         channels, kScaleFactor, base::Bind(
             &MultiChannelResamplerTest::ProvideInput,
             base::Unretained(this)));
+    // First prime the resampler with some junk data, so we can verify Flush().
+    fill_junk_values_ = true;
+    resampler.Resample(audio_bus_.get(), 1);
+    resampler.Flush();
+    fill_junk_values_ = false;
+    // If Flush() didn't work, the rest of the tests will fail.
     resampler.Resample(audio_bus_.get(), frames);
     TestValues(expected_max_rms_error, expected_max_error);
   }
 
   void HighLatencyTest(int channels) {
     MultiChannelTest(channels, kHighLatencySize, kHighLatencyMaxRMSError,
                      kHighLatencyMaxError);
   }
 
   void LowLatencyTest(int channels) {
@@ skipping 18 matching lines @@
 
     double rms_error = sqrt(
         sum_of_squares / (frames_ * audio_bus_->channels()));
 
     EXPECT_LE(rms_error, expected_max_rms_error);
     EXPECT_LE(max_error, expected_max_error);
   }
 
  protected:
   int frames_;
+  bool fill_junk_values_;
   scoped_ptr<AudioBus> audio_bus_;
 
   DISALLOW_COPY_AND_ASSIGN(MultiChannelResamplerTest);
 };
 
 TEST_P(MultiChannelResamplerTest, HighLatency) {
   HighLatencyTest(GetParam());
 }
 
 TEST_P(MultiChannelResamplerTest, LowLatency) {
   LowLatencyTest(GetParam());
 }
 
 // Test common channel layouts: mono, stereo, 5.1, 7.1.
 INSTANTIATE_TEST_CASE_P(
     MultiChannelResamplerTest, MultiChannelResamplerTest,
     testing::Values(1, 2, 6, 8));
 
 }  // namespace media