enable folding code for 6.1 and 7.1 surround sound.

BUG=54423
TEST=audio unittest and http://fbarchard0-w.ad.corp.google.com/testmatrix/gromit/gromit8.webm

Review URL: http://codereview.chromium.org/3353022

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@59224 0039d316-1c4b-4281-b951-d872f2087c98

5 files changed, 25 insertions, 12 deletions

diff --git a/media/audio/audio_util.cc b/media/audio/audio_util.cc
index 9f4e6da..e3e94cd 100644
--- a/media/audio/audio_util.cc
+++ b/media/audio/audio_util.cc
@@ -59,9 +59,9 @@ static int AddChannel(int val,
 
 template<class Format, class Fixed, int min_value, int max_value, int bias>
 static void FoldChannels(Format* buf_out,
-                  int sample_count,
-                  const float volume,
-                  int channels) {
+                         int sample_count,
+                         const float volume,
+                         int channels) {
   Format* buf_in = buf_out;
   const int center_volume = static_cast<int>(volume * 0.707f * 65536);
   const int fixed_volume = static_cast<int>(volume * 65536);
@@ -100,7 +100,7 @@ bool AdjustVolume(void* buf,
     memset(buf, 0, buflen);
     return true;
   }
-  if (channels > 0 && channels <= 6 && bytes_per_sample > 0) {
+  if (channels > 0 && channels <= 8 && bytes_per_sample > 0) {
     int sample_count = buflen / bytes_per_sample;
     const int fixed_volume = static_cast<int>(volume * 65536);
     if (bytes_per_sample == 1) {
@@ -130,7 +130,7 @@ bool FoldChannels(void* buf,
                   float volume) {
   DCHECK(buf);
   DCHECK(volume >= 0.0f && volume <= 1.0f);
-  if (channels >= 5 && channels <= 6 && bytes_per_sample > 0) {
+  if (channels > 2 && channels <= 8 && bytes_per_sample > 0) {
     int sample_count = buflen / (channels * bytes_per_sample);
     if (bytes_per_sample == 1) {
       FoldChannels<uint8, int32, -128, 127, 128>(
diff --git a/media/audio/audio_util_unittest.cc b/media/audio/audio_util_unittest.cc
index 6d5ad74..ae653c6 100644
--- a/media/audio/audio_util_unittest.cc
+++ b/media/audio/audio_util_unittest.cc
@@ -123,6 +123,21 @@ TEST(AudioUtilTest, FoldChannels_s32) {
   EXPECT_EQ(0, expected_test);
 }
 
+// Fold 7.1
+TEST(AudioUtilTest, FoldChannels71_s16) {
+  // Test FoldChannels() on 16 bit samples.
+  int16 samples_s16[8] = { 1, 3, 12, 7, 13, 17, 30, 40 };
+  int16 expected_s16[2] = { static_cast<int16>(12 * .707 + 1),
+                            static_cast<int16>(12 * .707 + 3) };
+  bool result_s16 = media::FoldChannels(samples_s16, sizeof(samples_s16),
+                                        8,  // 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);
+}
+
 // This mimics 1 second of audio at 48000 samples per second.
 // Running the unittest will produce timing.
 TEST(AudioUtilTest, DISABLED_FoldChannels_s16_benchmark) {
diff --git a/media/audio/linux/alsa_output.cc b/media/audio/linux/alsa_output.cc
index 422f91ba..98eaf14 100644
--- a/media/audio/linux/alsa_output.cc
+++ b/media/audio/linux/alsa_output.cc
@@ -771,12 +771,12 @@ snd_pcm_t* AlsaPcmOutputStream::AutoSelectDevice(unsigned int latency) {
 
   // For the kDefaultDevice device, we can only reliably depend on 2-channel
   // output to have the correct ordering according to Lennart.  For the channel
-  // formats that we know how to downmix from (5 channel to 6 channel), setup
+  // formats that we know how to downmix from (3 channel to 8 channel), setup
   // downmixing.
   //
   // TODO(ajwong): We need a SupportsFolding() function.
   uint32 default_channels = channels_;
-  if (default_channels >= 5 && default_channels <= 6) {
+  if (default_channels > 2 && default_channels <= 8) {
     should_downmix_ = true;
     default_channels = 2;
   }
diff --git a/media/audio/win/audio_manager_win.cc b/media/audio/win/audio_manager_win.cc
index 2e65879..3d5c137 100644
--- a/media/audio/win/audio_manager_win.cc
+++ b/media/audio/win/audio_manager_win.cc
@@ -17,12 +17,10 @@
 
 namespace {
 
-// Up to 6 channels can be passed to the driver.
+// Up to 8 channels can be passed to the driver.
 // This should work, given the right drivers, but graceful error handling is
 // needed.
-// In theory 7.1 could also be supported, but it has not been tested.
-// TODO(sergeyu): Test that 7.1 audio works.
-const int kWinMaxChannels = 6;
+const int kWinMaxChannels = 8;
 
 const int kWinMaxInputChannels = 2;
 const int kMaxSamplesPerPacket = media::Limits::kMaxSampleRate;
diff --git a/media/audio/win/waveout_output_win.h b/media/audio/win/waveout_output_win.h
index 7b87e4e..7bee81e 100644
--- a/media/audio/win/waveout_output_win.h
+++ b/media/audio/win/waveout_output_win.h
@@ -89,7 +89,7 @@ class PCMWaveOutAudioOutputStream : public AudioOutputStream {
   // Volume level from 0 to 1.
   float volume_;
 
-  // Channels from 0 to 6.
+  // Channels from 0 to 8.
   const int channels_;
 
   // Number of bytes yet to be played in the hardware buffer.