1 // Copyright (c) 2012 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 #ifndef MEDIA_AUDIO_AUDIO_PARAMETERS_H_ 6 #define MEDIA_AUDIO_AUDIO_PARAMETERS_H_ 7 8 #include "base/basictypes.h" 9 #include "base/time/time.h" 10 #include "media/base/channel_layout.h" 11 #include "media/base/media_export.h" 12 13 namespace media { 14 15 struct MEDIA_EXPORT AudioInputBufferParameters { 16 double volume; 17 uint32 size; 18 bool key_pressed; 19 }; 20 21 // Use a struct-in-struct approach to ensure that we can calculate the required 22 // size as sizeof(AudioInputBufferParameters) + #(bytes in audio buffer) without 23 // using packing. 24 struct MEDIA_EXPORT AudioInputBuffer { 25 AudioInputBufferParameters params; 26 int8 audio[1]; 27 }; 28 29 class MEDIA_EXPORT AudioParameters { 30 public: 31 // TODO(miu): Rename this enum to something that correctly reflects its 32 // semantics, such as "TransportScheme." 33 enum Format { 34 AUDIO_PCM_LINEAR = 0, // PCM is 'raw' amplitude samples. 35 AUDIO_PCM_LOW_LATENCY, // Linear PCM, low latency requested. 36 AUDIO_FAKE, // Creates a fake AudioOutputStream object. 37 AUDIO_LAST_FORMAT // Only used for validation of format. 38 }; 39 40 enum { 41 // Telephone quality sample rate, mostly for speech-only audio. 42 kTelephoneSampleRate = 8000, 43 // CD sampling rate is 44.1 KHz or conveniently 2x2x3x3x5x5x7x7. 44 kAudioCDSampleRate = 44100, 45 }; 46 47 // Bitmasks to determine whether certain platform (typically hardware) audio 48 // effects should be enabled. 49 enum PlatformEffectsMask { 50 NO_EFFECTS = 0x0, 51 ECHO_CANCELLER = 0x1, 52 DUCKING = 0x2, // Enables ducking if the OS supports it. 53 KEYBOARD_MIC = 0x4, 54 }; 55 56 AudioParameters(); 57 AudioParameters(Format format, ChannelLayout channel_layout, 58 int sample_rate, int bits_per_sample, 59 int frames_per_buffer); 60 AudioParameters(Format format, ChannelLayout channel_layout, 61 int input_channels, 62 int sample_rate, int bits_per_sample, 63 int frames_per_buffer, int effects); 64 AudioParameters(Format format, ChannelLayout channel_layout, 65 int channels, int input_channels, 66 int sample_rate, int bits_per_sample, 67 int frames_per_buffer, int effects); 68 69 void Reset(Format format, ChannelLayout channel_layout, 70 int channels, int input_channels, 71 int sample_rate, int bits_per_sample, 72 int frames_per_buffer); 73 74 // Checks that all values are in the expected range. All limits are specified 75 // in media::Limits. 76 bool IsValid() const; 77 78 // Returns size of audio buffer in bytes. 79 int GetBytesPerBuffer() const; 80 81 // Returns the number of bytes representing one second of audio. 82 int GetBytesPerSecond() const; 83 84 // Returns the number of bytes representing a frame of audio. 85 int GetBytesPerFrame() const; 86 87 // Returns the duration of this buffer as calculated from frames_per_buffer() 88 // and sample_rate(). 89 base::TimeDelta GetBufferDuration() const; 90 format()91 Format format() const { return format_; } channel_layout()92 ChannelLayout channel_layout() const { return channel_layout_; } sample_rate()93 int sample_rate() const { return sample_rate_; } bits_per_sample()94 int bits_per_sample() const { return bits_per_sample_; } frames_per_buffer()95 int frames_per_buffer() const { return frames_per_buffer_; } channels()96 int channels() const { return channels_; } input_channels()97 int input_channels() const { return input_channels_; } effects()98 int effects() const { return effects_; } 99 100 // Comparison with other AudioParams. 101 bool operator==(const AudioParameters& other) const { 102 return format_ == other.format() && 103 sample_rate_ == other.sample_rate() && 104 channel_layout_ == other.channel_layout() && 105 channels_ == other.channels() && 106 input_channels_ == other.input_channels() && 107 bits_per_sample_ == other.bits_per_sample() && 108 frames_per_buffer_ == other.frames_per_buffer() && 109 effects_ == other.effects(); 110 } 111 112 private: 113 // These members are mutable to support entire struct assignment. They should 114 // not be mutated individually. 115 Format format_; // Format of the stream. 116 ChannelLayout channel_layout_; // Order of surround sound channels. 117 int sample_rate_; // Sampling frequency/rate. 118 int bits_per_sample_; // Number of bits per sample. 119 int frames_per_buffer_; // Number of frames in a buffer. 120 121 int channels_; // Number of channels. Value set based on 122 // |channel_layout|. 123 int input_channels_; // Optional number of input channels. 124 // Normally 0, but can be set to specify 125 // synchronized I/O. 126 int effects_; // Bitmask using PlatformEffectsMask. 127 }; 128 129 // Comparison is useful when AudioParameters is used with std structures. 130 inline bool operator<(const AudioParameters& a, const AudioParameters& b) { 131 if (a.format() != b.format()) 132 return a.format() < b.format(); 133 if (a.channels() != b.channels()) 134 return a.channels() < b.channels(); 135 if (a.input_channels() != b.input_channels()) 136 return a.input_channels() < b.input_channels(); 137 if (a.sample_rate() != b.sample_rate()) 138 return a.sample_rate() < b.sample_rate(); 139 if (a.bits_per_sample() != b.bits_per_sample()) 140 return a.bits_per_sample() < b.bits_per_sample(); 141 return a.frames_per_buffer() < b.frames_per_buffer(); 142 } 143 144 } // namespace media 145 146 #endif // MEDIA_AUDIO_AUDIO_PARAMETERS_H_ 147