Surround Sound handling by folding 5 channels down to stereo.

media/audio/audio_util_unittest.cc

Index: media/audio/audio_util_unittest.cc
===================================================================
--- media/audio/audio_util_unittest.cc	(revision 21354)
+++ media/audio/audio_util_unittest.cc	(working copy)
@@ -50,6 +50,19 @@
   EXPECT_EQ(0, expected_test);
 }
 
+TEST(AudioUtilTest, AdjustVolume_s16_one) {
+  // Test AdjustVolume() on 16 bit samples.
+  int16 samples_s16[kNumberOfSamples] = { -4, 0x40, -32768, 123 };
+  int16 expected_s16[kNumberOfSamples] = { -4, 0x40, -32768, 123 };
+  bool result_s16 = media::AdjustVolume(samples_s16, sizeof(samples_s16),
+                                        2,  // channels.
+                                        sizeof(samples_s16[0]),
+                                        1.0f);
+  EXPECT_EQ(true, result_s16);
+  int expected_test = memcmp(samples_s16, expected_s16, sizeof(expected_s16));
+  EXPECT_EQ(0, expected_test);
+}
+
 TEST(AudioUtilTest, AdjustVolume_s32) {
   // Test AdjustVolume() on 32 bit samples.
   int32 samples_s32[kNumberOfSamples] = { -4, 0x40, -32768, 123 };
@@ -63,4 +76,62 @@
   EXPECT_EQ(0, expected_test);
 }
 
+TEST(AudioUtilTest, FoldChannels_u8) {
+  // Test AdjustVolume() on 16 bit samples.
+  uint8 samples_u8[6] = { 130, 100, 150, 70, 130, 170 };
+  uint8 expected_u8[2] = { 43, 153 };
+  bool result_u8 = media::FoldChannels(samples_u8, sizeof(samples_u8),
+                                        6,  // channels.
+                                        sizeof(samples_u8[0]),
+                                        1.0f);
+  EXPECT_EQ(true, result_u8);
+  int expected_test = memcmp(samples_u8, expected_u8, sizeof(expected_u8));
+  EXPECT_EQ(0, expected_test);
+}
+
+TEST(AudioUtilTest, FoldChannels_s16) {
+  // Test AdjustVolume() on 16 bit samples.
+  int16 samples_s16[6] = { 12, 1, 3, 7, 13, 17 };
+  int16 expected_s16[2] = { static_cast<int16>(12 * .707 + 1 + 7),
+                            static_cast<int16>(12 * .707 + 3 + 13) };
+  bool result_s16 = media::FoldChannels(samples_s16, sizeof(samples_s16),
+                                        6,  // channels.
+                                        sizeof(samples_s16[0]),
+                                        1.00f);
+  EXPECT_EQ(true, result_s16);
+  int expected_test = memcmp(samples_s16, expected_s16, sizeof(expected_s16));
+  EXPECT_EQ(0, expected_test);
+}
+
+TEST(AudioUtilTest, FoldChannels_s32) {
+  // Test AdjustVolume() on 16 bit samples.
+  int32 samples_s32[6] = { 12, 1, 3, 7, 13, 17 };
+  int32 expected_s32[2] = { static_cast<int16>(12 * .707 + 1 + 7),
+                            static_cast<int16>(12 * .707 + 3 + 13) };
+  bool result_s32 = media::FoldChannels(samples_s32, sizeof(samples_s32),
+                                        6,  // channels.
+                                        sizeof(samples_s32[0]),
+                                        1.00f);
+  EXPECT_EQ(true, result_s32);
+  int expected_test = memcmp(samples_s32, expected_s32, sizeof(expected_s32));
+  EXPECT_EQ(0, expected_test);
+}
+
+// This mimics 1 second of audio at 48000 samples per second.
+// Running the unittest will produce timing.
+TEST(AudioUtilTest, FoldChannels_s16_benchmark) {
+  const int kBufferSize = 1024 * 6;
+  // Test AdjustVolume() on 16 bit samples.
+  for (int i = 0; i < 48000; ++i) {
+    int16 samples_s16[kBufferSize];
+    for (int j = 0; j < kBufferSize; ++j)
+      samples_s16[j] = j;
+
+    bool result_s16 = media::FoldChannels(samples_s16, sizeof(samples_s16),
+                                          6,  // channels.
+                                          sizeof(samples_s16[0]),
+                                          0.5f);
+    EXPECT_EQ(true, result_s16);
+  }
+}
 }  // namespace media