Enable float audio output on L+ Android devices.

media/audio/android/opensles_output.h

Index: media/audio/android/opensles_output.h
diff --git a/media/audio/android/opensles_output.h b/media/audio/android/opensles_output.h
index 671dbdec4a337c0a28856a08955b2f3b7daefae5..80d8929769a68f7cd46ed1afeef117ff5838346d 100644
--- a/media/audio/android/opensles_output.h
+++ b/media/audio/android/opensles_output.h
@@ -21,6 +21,25 @@
 #include "media/base/audio_parameters.h"
 #include "media/base/audio_timestamp_helper.h"
 
+// On L+, we want to use floating point output for better fidelity.
+#if __ANDROID_API__ < 21
+#define SL_ANDROID_PCM_REPRESENTATION_SIGNED_INT ((SLuint32)0x00000001)
+#define SL_ANDROID_PCM_REPRESENTATION_UNSIGNED_INT ((SLuint32)0x00000002)
+#define SL_ANDROID_PCM_REPRESENTATION_FLOAT ((SLuint32)0x00000003)
+#define SL_ANDROID_DATAFORMAT_PCM_EX ((SLuint32)0x00000004)
+
+typedef struct SLAndroidDataFormat_PCM_EX_ {
+  SLuint32 formatType;
+  SLuint32 numChannels;
+  SLuint32 sampleRate;
+  SLuint32 bitsPerSample;
+  SLuint32 containerSize;
+  SLuint32 channelMask;
+  SLuint32 endianness;
+  SLuint32 representation;
+} SLAndroidDataFormat_PCM_EX;
+#endif
+
 namespace media {
 
 class AudioManagerAndroid;
@@ -101,14 +120,13 @@ class OpenSLESOutputStream : public AudioOutputStream {
   SLAndroidSimpleBufferQueueItf simple_buffer_queue_;
 
   SLDataFormat_PCM format_;
+  SLAndroidDataFormat_PCM_EX float_format_;
 
   // Audio buffers that are allocated during Open() based on parameters given
   // during construction.
   uint8_t* audio_data_[kMaxNumOfBuffersInQueue];
 
   int active_buffer_index_;
-  int bytes_per_frame_;
-  size_t buffer_size_bytes_;
 
   bool started_;
 
@@ -123,6 +141,12 @@ class OpenSLESOutputStream : public AudioOutputStream {
 
   int samples_per_second_;
 
+  // On Android 5.0+ we can output directly to float instead of in integer.
+  bool have_float_output_;
+
+  int bytes_per_frame_;
+  size_t buffer_size_bytes_;
+
   // Used to calculate the delay value for each OnMoreData() call.
   AudioTimestampHelper delay_calculator_;