Add MultiChannelResampler wrapper for SincResampler.

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"
+#include "media/base/multi_channel_resampler.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace media {
+
+// Just test a basic resampling case.  The SincResampler unit test will take
+// care of accuracy testing; we just need to check that multichannel works as
+// expected within some tolerance.
+static const float kScaleFactor = 44100.0f / 48000.0f;
+
+// Simulate large and small sample requests used by the different audio paths.
+static const int kHighLatencySize = 8192;
+// Low latency buffers show a larger error than high latency ones.  Which makes
+// sense since each error represents a larger portion of the total request.
+static const int kLowLatencySize = 128;
+
+// Test fill value.
+static const float kFillValue = 0.1f;
+
+// Chosen arbitrarily based on what each resampler reported during testing.
+static const double kLowLatencyMaxRMSError = 0.001;
+static const double kLowLatencyMaxError = 0.0068;
+static const double kHighLatencyMaxRMSError = 0.00013;
+static const double kHighLatencyMaxError = 0.0068;
+
+class MultiChannelResamplerTestCase
+    : public testing::TestWithParam<int> {
+ public:
+  MultiChannelResamplerTestCase() {}
+  virtual ~MultiChannelResamplerTestCase() {
+    if (!audio_data_.empty()) {
+      for (size_t i = 0; i < audio_data_.size(); ++i)
+        delete [] audio_data_[i];
+      audio_data_.clear();
+    }
+  }
+
+  void InitializeAudioData(int channels, int frames) {
+    frames_ = frames;
+    audio_data_.reserve(channels);
+    for (int i = 0; i < channels; ++i) {
+      audio_data_.push_back(new float[frames]);
+
+      // Zero initialize so we can be sure every value has been provided.
+      memset(audio_data_[i], 0, sizeof(*audio_data_[i]) * frames);
+    }
+  }
+
+  // MultiChannelResampler::MultiChannelAudioSourceProvider implementation, just
+  // fills the provided audio_data with |kFillValue|.
+  virtual void ProvideInput(const std::vector<float*>& audio_data,
+                            int number_of_frames) {
+    EXPECT_EQ(audio_data.size(), audio_data_.size());
+    for (size_t i = 0; i < audio_data.size(); ++i)
+      for (int j = 0; j < number_of_frames; ++j)
+        audio_data[i][j] = kFillValue;
+  }
+
+  void MultiChannelTest(int channels, int frames, double expected_max_rms_error,
+                        double expected_max_error) {
+    InitializeAudioData(channels, frames);
+    MultiChannelResampler resampler(
+        channels, kScaleFactor, base::Bind(
+            &MultiChannelResamplerTestCase::ProvideInput,
+            base::Unretained(this)));
+    resampler.Resample(audio_data_, frames);
+    TestValues(expected_max_rms_error, expected_max_error);
+  }
+
+  void HighLatencyTest(int channels) {
+    MultiChannelTest(channels, kHighLatencySize, kHighLatencyMaxRMSError,
+                     kHighLatencyMaxError);
+  }
+
+  void LowLatencyTest(int channels) {
+    MultiChannelTest(channels, kLowLatencySize, kLowLatencyMaxRMSError,
+                     kLowLatencyMaxError);
+  }
+
+  void TestValues(double expected_max_rms_error, double expected_max_error ) {
+    // Calculate Root-Mean-Square-Error for the resampling.
+    double max_error = 0.0;
+    double sum_of_squares = 0.0;
+    for (size_t i = 0; i < audio_data_.size(); ++i) {
+      for (int j = 0; j < frames_; ++j) {
+        // Ensure all values are accounted for.
+        ASSERT_NE(audio_data_[i][j], 0);
+
+        double error = fabs(audio_data_[i][j] - kFillValue);
+        max_error = std::max(max_error, error);
+        sum_of_squares += error * error;
+      }
+    }
+
+    double rms_error = sqrt(
+        sum_of_squares / (frames_ * audio_data_.size()));
+
+    EXPECT_LE(rms_error, expected_max_rms_error);
+    EXPECT_LE(max_error, expected_max_error);
+  }
+
+ protected:
+  int frames_;
+  std::vector<float*> audio_data_;
+
+  DISALLOW_COPY_AND_ASSIGN(MultiChannelResamplerTestCase);
+};
+
+TEST_P(MultiChannelResamplerTestCase, HighLatency) {
+  HighLatencyTest(GetParam());
+}
+
+TEST_P(MultiChannelResamplerTestCase, LowLatency) {
+  LowLatencyTest(GetParam());
+}
+
+// Test common channel layouts: mono, stereo, 5.1, 7.1.
+INSTANTIATE_TEST_CASE_P(
+    MultiChannelResamplerTest, MultiChannelResamplerTestCase,
+    testing::Values(1, 2, 6, 8));
+
+}  // namespace media