Enable float audio output on L+ Android devices.

media/audio/android/opensles_output.h

 // 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.
 
 #ifndef MEDIA_AUDIO_ANDROID_OPENSLES_OUTPUT_H_
 #define MEDIA_AUDIO_ANDROID_OPENSLES_OUTPUT_H_
 
 #include <SLES/OpenSLES.h>
 #include <SLES/OpenSLES_Android.h>
 #include <stddef.h>
 #include <stdint.h>
 
 #include <memory>
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "base/synchronization/lock.h"
 #include "base/threading/thread_checker.h"
 #include "media/audio/android/opensles_util.h"
 #include "media/audio/audio_io.h"
 #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;
 
 // Implements PCM audio output support for Android using the OpenSLES API.
 // This class is created and lives on the Audio Manager thread but recorded
 // audio buffers are given to us from an internal OpenSLES audio thread.
 // All public methods should be called on the Audio Manager thread.
 class OpenSLESOutputStream : public AudioOutputStream {
  public:
@@ skipping 60 matching lines @@
   media::ScopedSLObjectItf engine_object_;
   media::ScopedSLObjectItf player_object_;
   media::ScopedSLObjectItf output_mixer_;
 
   SLPlayItf player_;
 
   // Buffer queue recorder interface.
   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_;
 
   // Volume control coming from hardware. It overrides |volume_| when it's
   // true. Otherwise, use |volume_| for scaling.
   // This is needed because platform voice volume never goes to zero in
   // COMMUNICATION mode on Android.
   bool muted_;
 
   // Volume level from 0 to 1.
   float volume_;
 
   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_;
 
   // Container for retrieving data from AudioSourceCallback::OnMoreData().
   std::unique_ptr<AudioBus> audio_bus_;
 
   DISALLOW_COPY_AND_ASSIGN(OpenSLESOutputStream);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_AUDIO_ANDROID_OPENSLES_OUTPUT_H_