media/base/audio_hardware_config.cc

   1 // Copyright (c) 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 "media/base/audio_hardware_config.h"
   6
   7 #include <algorithm>
   8
   9 #include "base/logging.h"
  10 #include "build/build_config.h"
  11
  12 using base::AutoLock;
  13 using media::AudioParameters;
  14
  15 namespace media {
  16
  17 #if defined(OS_LINUX) || defined(OS_MACOSX)
  18 #define HIGH_LATENCY_AUDIO_SUPPORT 1
  19 #endif
  20
  21 #if defined(HIGH_LATENCY_AUDIO_SUPPORT)
  22 // Taken from "Bit Twiddling Hacks"
  23 // http://graphics.stanford.edu/~seander/bithacks.html#RoundUpPowerOf2
  24 static uint32_t RoundUpToPowerOfTwo(uint32_t v) {
  25   v--;
  26   v |= v >> 1;
  27   v |= v >> 2;
  28   v |= v >> 4;
  29   v |= v >> 8;
  30   v |= v >> 16;
  31   v++;
  32   return v;
  33 }
  34 #endif
  35
  36 AudioHardwareConfig::AudioHardwareConfig(
  37     const AudioParameters& input_params,
  38     const AudioParameters& output_params)
  39     : input_params_(input_params),
  40       output_params_(output_params) {}
  41
  42 AudioHardwareConfig::~AudioHardwareConfig() {}
  43
  44 int AudioHardwareConfig::GetOutputBufferSize() const {
  45   AutoLock auto_lock(config_lock_);
  46   return output_params_.frames_per_buffer();
  47 }
  48
  49 int AudioHardwareConfig::GetOutputSampleRate() const {
  50   AutoLock auto_lock(config_lock_);
  51   return output_params_.sample_rate();
  52 }
  53
  54 ChannelLayout AudioHardwareConfig::GetOutputChannelLayout() const {
  55   AutoLock auto_lock(config_lock_);
  56   return output_params_.channel_layout();
  57 }
  58
  59 int AudioHardwareConfig::GetOutputChannels() const {
  60   AutoLock auto_lock(config_lock_);
  61   return output_params_.channels();
  62 }
  63
  64 int AudioHardwareConfig::GetInputSampleRate() const {
  65   AutoLock auto_lock(config_lock_);
  66   return input_params_.sample_rate();
  67 }
  68
  69 ChannelLayout AudioHardwareConfig::GetInputChannelLayout() const {
  70   AutoLock auto_lock(config_lock_);
  71   return input_params_.channel_layout();
  72 }
  73
  74 int AudioHardwareConfig::GetInputChannels() const {
  75   AutoLock auto_lock(config_lock_);
  76   return input_params_.channels();
  77 }
  78
  79 media::AudioParameters
  80 AudioHardwareConfig::GetInputConfig() const {
  81   AutoLock auto_lock(config_lock_);
  82   return input_params_;
  83 }
  84
  85 media::AudioParameters
  86 AudioHardwareConfig::GetOutputConfig() const {
  87   AutoLock auto_lock(config_lock_);
  88   return output_params_;
  89 }
  90
  91 void AudioHardwareConfig::UpdateInputConfig(
  92     const AudioParameters& input_params) {
  93   AutoLock auto_lock(config_lock_);
  94   input_params_ = input_params;
  95 }
  96
  97 void AudioHardwareConfig::UpdateOutputConfig(
  98     const AudioParameters& output_params) {
  99   AutoLock auto_lock(config_lock_);
 100   output_params_ = output_params;
 101 }
 102
 103 int AudioHardwareConfig::GetHighLatencyBufferSize() const {
 104   AutoLock auto_lock(config_lock_);
 105 #if defined(HIGH_LATENCY_AUDIO_SUPPORT)
 106   // Empirically, use the nearest higher power of two buffer size corresponding
 107   // to 20 ms worth of samples.  For a given sample rate, this works out to:
 108   //
 109   //     <= 3200   : 64
 110   //     <= 6400   : 128
 111   //     <= 12800  : 256
 112   //     <= 25600  : 512
 113   //     <= 51200  : 1024
 114   //     <= 102400 : 2048
 115   //     <= 204800 : 4096
 116   //
 117   // On Linux, the minimum hardware buffer size is 512, so the lower calculated
 118   // values are unused.  OSX may have a value as low as 128.  Windows is device
 119   // dependent but will generally be sample_rate() / 100.
 120   const int high_latency_buffer_size =
 121       RoundUpToPowerOfTwo(2 * output_params_.sample_rate() / 100);
 122   return std::max(output_params_.frames_per_buffer(), high_latency_buffer_size);
 123 #else
 124   return output_params_.frames_per_buffer();
 125 #endif
 126 }
 127
 128 }  // namespace media