media/base/audio_hash_unittest.cc

   1 // Copyright 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "base/logging.h"
   6 #include "media/base/audio_bus.h"
   7 #include "media/base/audio_hash.h"
   8 #include "media/base/fake_audio_render_callback.h"
   9 #include "testing/gtest/include/gtest/gtest.h"
  10
  11 namespace media {
  12
  13 static const int kChannelCount = 2;
  14 static const int kFrameCount = 1024;
  15
  16 class AudioHashTest : public testing::Test {
  17  public:
  18   AudioHashTest()
  19       : bus_one_(AudioBus::Create(kChannelCount, kFrameCount)),
  20         bus_two_(AudioBus::Create(kChannelCount, kFrameCount)),
  21         fake_callback_(0.01) {
  22
  23     // Fill each channel in each bus with unique data.
  24     GenerateUniqueChannels(bus_one_.get());
  25     GenerateUniqueChannels(bus_two_.get());
  26   }
  27
  28   void GenerateUniqueChannels(AudioBus* audio_bus) {
  29     // Use an AudioBus wrapper to avoid an extra memcpy when filling channels.
  30     scoped_ptr<AudioBus> wrapped_bus = AudioBus::CreateWrapper(1);
  31     wrapped_bus->set_frames(audio_bus->frames());
  32
  33     // Since FakeAudioRenderCallback generates only a single channel of unique
  34     // audio data, we need to fill each channel manually.
  35     for (int ch = 0; ch < audio_bus->channels(); ++ch) {
  36       wrapped_bus->SetChannelData(0, audio_bus->channel(ch));
  37       fake_callback_.Render(wrapped_bus.get(), 0);
  38     }
  39   }
  40
  41   virtual ~AudioHashTest() {}
  42
  43  protected:
  44   scoped_ptr<AudioBus> bus_one_;
  45   scoped_ptr<AudioBus> bus_two_;
  46   FakeAudioRenderCallback fake_callback_;
  47
  48   DISALLOW_COPY_AND_ASSIGN(AudioHashTest);
  49 };
  50
  51 // Ensure the same data hashes the same.
  52 TEST_F(AudioHashTest, Equivalence) {
  53   AudioHash hash_one;
  54   hash_one.Update(bus_one_.get(), bus_one_->frames());
  55
  56   AudioHash hash_two;
  57   hash_two.Update(bus_one_.get(), bus_one_->frames());
  58
  59   EXPECT_EQ(hash_one.ToString(), hash_two.ToString());
  60 }
  61
  62 // Ensure sample order matters to the hash.
  63 TEST_F(AudioHashTest, SampleOrder) {
  64   AudioHash original_hash;
  65   original_hash.Update(bus_one_.get(), bus_one_->frames());
  66
  67   // Swap a sample in the bus.
  68   std::swap(bus_one_->channel(0)[0], bus_one_->channel(0)[1]);
  69
  70   AudioHash swapped_hash;
  71   swapped_hash.Update(bus_one_.get(), bus_one_->frames());
  72
  73   EXPECT_NE(original_hash.ToString(), swapped_hash.ToString());
  74 }
  75
  76 // Ensure channel order matters to the hash.
  77 TEST_F(AudioHashTest, ChannelOrder) {
  78   AudioHash original_hash;
  79   original_hash.Update(bus_one_.get(), bus_one_->frames());
  80
  81   // Reverse channel order for the same sample data.
  82   const int channels = bus_one_->channels();
  83   scoped_ptr<AudioBus> swapped_ch_bus = AudioBus::CreateWrapper(channels);
  84   swapped_ch_bus->set_frames(bus_one_->frames());
  85   for (int i = channels - 1; i >= 0; --i)
  86     swapped_ch_bus->SetChannelData(channels - (i + 1), bus_one_->channel(i));
  87
  88   AudioHash swapped_hash;
  89   swapped_hash.Update(swapped_ch_bus.get(), swapped_ch_bus->frames());
  90
  91   EXPECT_NE(original_hash.ToString(), swapped_hash.ToString());
  92 }
  93
  94 // Ensure bus order matters to the hash.
  95 TEST_F(AudioHashTest, BusOrder) {
  96   AudioHash original_hash;
  97   original_hash.Update(bus_one_.get(), bus_one_->frames());
  98   original_hash.Update(bus_two_.get(), bus_two_->frames());
  99
 100   AudioHash reordered_hash;
 101   reordered_hash.Update(bus_two_.get(), bus_two_->frames());
 102   reordered_hash.Update(bus_one_.get(), bus_one_->frames());
 103
 104   EXPECT_NE(original_hash.ToString(), reordered_hash.ToString());
 105 }
 106
 107 // Ensure bus order matters to the hash even with empty buses.
 108 TEST_F(AudioHashTest, EmptyBusOrder) {
 109   bus_one_->Zero();
 110   bus_two_->Zero();
 111
 112   AudioHash one_bus_hash;
 113   one_bus_hash.Update(bus_one_.get(), bus_one_->frames());
 114
 115   AudioHash two_bus_hash;
 116   two_bus_hash.Update(bus_one_.get(), bus_one_->frames());
 117   two_bus_hash.Update(bus_two_.get(), bus_two_->frames());
 118
 119   EXPECT_NE(one_bus_hash.ToString(), two_bus_hash.ToString());
 120 }
 121
 122 // Where A = [0, n], ensure hash(A[0:n/2]), hash(A[n/2:n]) and hash(A) result
 123 // in the same value.
 124 TEST_F(AudioHashTest, HashIgnoresUpdateOrder) {
 125   AudioHash full_hash;
 126   full_hash.Update(bus_one_.get(), bus_one_->frames());
 127
 128   AudioHash half_hash;
 129   half_hash.Update(bus_one_.get(), bus_one_->frames() / 2);
 130
 131   // Create a new bus representing the second half of |bus_one_|.
 132   const int half_frames = bus_one_->frames() / 2;
 133   const int channels = bus_one_->channels();
 134   scoped_ptr<AudioBus> half_bus = AudioBus::CreateWrapper(channels);
 135   half_bus->set_frames(half_frames);
 136   for (int i = 0; i < channels; ++i)
 137     half_bus->SetChannelData(i, bus_one_->channel(i) + half_frames);
 138
 139   half_hash.Update(half_bus.get(), half_bus->frames());
 140   EXPECT_EQ(full_hash.ToString(), half_hash.ToString());
 141 }
 142
 143 // Ensure approximate hashes pass verification.
 144 TEST_F(AudioHashTest, VerifySimilarHash) {
 145   AudioHash hash_one;
 146   hash_one.Update(bus_one_.get(), bus_one_->frames());
 147
 148   // Twiddle the values inside the first bus.
 149   float* channel = bus_one_->channel(0);
 150   for (int i = 0; i < bus_one_->frames(); i += bus_one_->frames() / 64)
 151     channel[i] += 0.0001f;
 152
 153   AudioHash hash_two;
 154   hash_two.Update(bus_one_.get(), bus_one_->frames());
 155
 156   EXPECT_EQ(hash_one.ToString(), hash_two.ToString());
 157
 158   // Twiddle the values too much...
 159   for (int i = 0; i < bus_one_->frames(); ++i)
 160     channel[i] += 0.0001f;
 161
 162   AudioHash hash_three;
 163   hash_three.Update(bus_one_.get(), bus_one_->frames());
 164   EXPECT_NE(hash_one.ToString(), hash_three.ToString());
 165 }
 166
 167 }  // namespace media