android audio概念大全

1.audio stream type(10類audio stream類型）

這些類型代表了android系統中所有的聲音種類，通過不同的stream标志，可以精确的控制這些audio stream。

public static final int STREAM_VOICE_CALL = 0;

public static final int STREAM_SYSTEM = 1;

public static final int STREAM_RING = 2;

public static final int STREAM_MUSIC = 3;

public static final int STREAM_ALARM = 4;

public static final int STREAM_NOTIFICATION = 5;

public static final int STREAM_BLUETOOTH_SCO = 6;

public static final int STREAM_SYSTEM_ENFORCED = 7;

public static final int STREAM_DTMF = 8;

public static final int STREAM_TTS = 9;

還有兩個用于統計stream的數量：

// Expose only the getter method publicly so we can change it in the future

private static final int NUM_STREAM_TYPES = 10;

public static final int getNumStreamTypes() { return NUM_STREAM_TYPES; }

2.采樣率：

// sample rate, note these values are subject to change

if ( (sampleRateInHz < 4000) || (sampleRateInHz > 48000) ) {

loge("getMinBufferSize(): " + sampleRateInHz +"Hz is not a supported sample rate.");

return AudioTrack.ERROR_BAD_VALUE;

}

int size = native_get_min_buff_size(sampleRateInHz, channelCount, audioFormat);

if ((size == -1) || (size == 0)) {

loge("getMinBufferSize(): error querying hardware");

return AudioTrack.ERROR;

}

else {

return size;

}

從以上代碼可以看出android audio采樣率在4k<=ampleRateInHz<=48K之間，其他的就認為是錯誤值，

這個在android中直接關系到buffersize的大小，

3.聲道數：

private int mChannelCount = 1;

預設值是1.

4.采樣精度：

有以下audioformat.java檔案，可以看出audio的格式定義.

package android.media;

public class AudioFormat {

//---------------------------------------------------------

// Constants

//--------------------

public static final int ENCODING_INVALID = 0;

public static final int ENCODING_DEFAULT = 1;

// These two values must be kept in sync with JNI code for AudioTrack, AudioRecord

public static final int ENCODING_PCM_16BIT = 2; //采樣精度8bit, 一個位元組

public static final int ENCODING_PCM_8BIT = 3; //采樣精度8bit, 一個位元組

@Deprecated public static final int CHANNEL_CONFIGURATION_INVALID = 0;

@Deprecated public static final int CHANNEL_CONFIGURATION_DEFAULT = 1;

@Deprecated public static final int CHANNEL_CONFIGURATION_MONO = 2;

@Deprecated public static final int CHANNEL_CONFIGURATION_STEREO = 3;

public static final int CHANNEL_INVALID = 0;

public static final int CHANNEL_OUT_DEFAULT = 1;

//以上是關于CHANNEL的定義。

// Channel mask definitions below are translated to the native values defined in

// in /system/core/include/system/audio.h in the JNI code of AudioTrack

public static final int CHANNEL_OUT_FRONT_LEFT = 0x4;

public static final int CHANNEL_OUT_FRONT_RIGHT = 0x8;

public static final int CHANNEL_OUT_FRONT_CENTER = 0x10;

public static final int CHANNEL_OUT_LOW_FREQUENCY = 0x20;

public static final int CHANNEL_OUT_BACK_LEFT = 0x40;

public static final int CHANNEL_OUT_BACK_RIGHT = 0x80;

public static final int CHANNEL_OUT_FRONT_LEFT_OF_CENTER = 0x100;

public static final int CHANNEL_OUT_FRONT_RIGHT_OF_CENTER = 0x200;

public static final int CHANNEL_OUT_BACK_CENTER = 0x400;

public static final int CHANNEL_OUT_SIDE_LEFT = 0x800;

public static final int CHANNEL_OUT_SIDE_RIGHT = 0x1000;

public static final int CHANNEL_OUT_TOP_CENTER = 0x2000;

public static final int CHANNEL_OUT_TOP_FRONT_LEFT = 0x4000;

public static final int CHANNEL_OUT_TOP_FRONT_CENTER = 0x8000;

public static final int CHANNEL_OUT_TOP_FRONT_RIGHT = 0x10000;

public static final int CHANNEL_OUT_TOP_BACK_LEFT = 0x20000;

public static final int CHANNEL_OUT_TOP_BACK_CENTER = 0x40000;

public static final int CHANNEL_OUT_TOP_BACK_RIGHT = 0x80000;

public static final int CHANNEL_OUT_MONO = CHANNEL_OUT_FRONT_LEFT;

public static final int CHANNEL_OUT_STEREO = (CHANNEL_OUT_FRONT_LEFT | CHANNEL_OUT_FRONT_RIGHT);

public static final int CHANNEL_OUT_QUAD = (CHANNEL_OUT_FRONT_LEFT | CHANNEL_OUT_FRONT_RIGHT |

CHANNEL_OUT_BACK_LEFT | CHANNEL_OUT_BACK_RIGHT);

public static final int CHANNEL_OUT_SURROUND = (CHANNEL_OUT_FRONT_LEFT | CHANNEL_OUT_FRONT_RIGHT |

CHANNEL_OUT_FRONT_CENTER | CHANNEL_OUT_BACK_CENTER);

public static final int CHANNEL_OUT_5POINT1 = (CHANNEL_OUT_FRONT_LEFT | CHANNEL_OUT_FRONT_RIGHT |

CHANNEL_OUT_FRONT_CENTER | CHANNEL_OUT_LOW_FREQUENCY | CHANNEL_OUT_BACK_LEFT | CHANNEL_OUT_BACK_RIGHT);

public static final int CHANNEL_OUT_7POINT1 = (CHANNEL_OUT_FRONT_LEFT | CHANNEL_OUT_FRONT_RIGHT |

CHANNEL_OUT_FRONT_CENTER | CHANNEL_OUT_LOW_FREQUENCY | CHANNEL_OUT_BACK_LEFT | CHANNEL_OUT_BACK_RIGHT |

CHANNEL_OUT_FRONT_LEFT_OF_CENTER | CHANNEL_OUT_FRONT_RIGHT_OF_CENTER);

public static final int CHANNEL_OUT_7POINT1_SURROUND = (

CHANNEL_OUT_FRONT_LEFT | CHANNEL_OUT_FRONT_CENTER | CHANNEL_OUT_FRONT_RIGHT |

CHANNEL_OUT_SIDE_LEFT | CHANNEL_OUT_SIDE_RIGHT |

CHANNEL_OUT_BACK_LEFT | CHANNEL_OUT_BACK_RIGHT |

CHANNEL_OUT_LOW_FREQUENCY);

//輸出到各個輸出到裝置的定義：

public static final int CHANNEL_IN_DEFAULT = 1;

public static final int CHANNEL_IN_LEFT = 0x4;

public static final int CHANNEL_IN_RIGHT = 0x8;

public static final int CHANNEL_IN_FRONT = 0x10;

public static final int CHANNEL_IN_BACK = 0x20;

public static final int CHANNEL_IN_LEFT_PROCESSED = 0x40;

public static final int CHANNEL_IN_RIGHT_PROCESSED = 0x80;

public static final int CHANNEL_IN_FRONT_PROCESSED = 0x100;

public static final int CHANNEL_IN_BACK_PROCESSED = 0x200;

public static final int CHANNEL_IN_PRESSURE = 0x400;

public static final int CHANNEL_IN_X_AXIS = 0x800;

public static final int CHANNEL_IN_Y_AXIS = 0x1000;

public static final int CHANNEL_IN_Z_AXIS = 0x2000;

public static final int CHANNEL_IN_VOICE_UPLINK = 0x4000;

public static final int CHANNEL_IN_VOICE_DNLINK = 0x8000;

public static final int CHANNEL_IN_MONO = CHANNEL_IN_FRONT;

public static final int CHANNEL_IN_STEREO = (CHANNEL_IN_LEFT | CHANNEL_IN_RIGHT);

//CHANNEL_IN的定義：

}

5.audio資料加載模式：

MODE_STREAM ：一次次以buffersize大小把音頻檔案write到audiotrack中。

MODE_STATIC：一次性把音頻檔案write到audiotrack中。

6.audio devices:

6.1Input輸入裝置定義：

// input devices

public static final int DEVICE_IN_COMMUNICATION = 0x10000;

public static final int DEVICE_IN_AMBIENT = 0x20000;

public static final int DEVICE_IN_BUILTIN_MIC1 = 0x40000;

public static final int DEVICE_IN_BUILTIN_MIC2 = 0x80000;

public static final int DEVICE_IN_MIC_ARRAY = 0x100000;

public static final int DEVICE_IN_BLUETOOTH_SCO_HEADSET = 0x200000;

public static final int DEVICE_IN_WIRED_HEADSET = 0x400000;

public static final int DEVICE_IN_AUX_DIGITAL = 0x800000;

public static final int DEVICE_IN_DEFAULT = 0x80000000;

6.2Output:輸出裝置定義：

// output devices, be sure to update AudioManager.java also

public static final int DEVICE_OUT_EARPIECE = 0x1;

public static final int DEVICE_OUT_SPEAKER = 0x2;

public static final int DEVICE_OUT_WIRED_HEADSET = 0x4;

public static final int DEVICE_OUT_WIRED_HEADPHONE = 0x8;

public static final int DEVICE_OUT_BLUETOOTH_SCO = 0x10;

public static final int DEVICE_OUT_BLUETOOTH_SCO_HEADSET = 0x20;

public static final int DEVICE_OUT_BLUETOOTH_SCO_CARKIT = 0x40;

public static final int DEVICE_OUT_BLUETOOTH_A2DP = 0x80;

public static final int DEVICE_OUT_BLUETOOTH_A2DP_HEADPHONES = 0x100;

public static final int DEVICE_OUT_BLUETOOTH_A2DP_SPEAKER = 0x200;

public static final int DEVICE_OUT_AUX_DIGITAL = 0x400;

public static final int DEVICE_OUT_ANLG_DOCK_HEADSET = 0x800;

public static final int DEVICE_OUT_DGTL_DOCK_HEADSET = 0x1000;

public static final int DEVICE_OUT_USB_ACCESSORY = 0x2000;

public static final int DEVICE_OUT_USB_DEVICE = 0x4000;

public static final int DEVICE_OUT_DEFAULT = 0x8000;

public static final int DEVICE_OUT_ALL = (DEVICE_OUT_EARPIECE |

DEVICE_OUT_SPEAKER |

DEVICE_OUT_WIRED_HEADSET |

DEVICE_OUT_WIRED_HEADPHONE |

DEVICE_OUT_BLUETOOTH_SCO |

DEVICE_OUT_BLUETOOTH_SCO_HEADSET |

DEVICE_OUT_BLUETOOTH_SCO_CARKIT |

DEVICE_OUT_BLUETOOTH_A2DP |

DEVICE_OUT_BLUETOOTH_A2DP_HEADPHONES |

DEVICE_OUT_BLUETOOTH_A2DP_SPEAKER |

DEVICE_OUT_AUX_DIGITAL |

DEVICE_OUT_ANLG_DOCK_HEADSET |

DEVICE_OUT_DGTL_DOCK_HEADSET |

DEVICE_OUT_USB_ACCESSORY |

DEVICE_OUT_USB_DEVICE |

DEVICE_OUT_DEFAULT);

public static final int DEVICE_OUT_ALL_A2DP = (DEVICE_OUT_BLUETOOTH_A2DP |

DEVICE_OUT_BLUETOOTH_A2DP_HEADPHONES |

DEVICE_OUT_BLUETOOTH_A2DP_SPEAKER);

public static final int DEVICE_OUT_ALL_SCO = (DEVICE_OUT_BLUETOOTH_SCO |

DEVICE_OUT_BLUETOOTH_SCO_HEADSET |

DEVICE_OUT_BLUETOOTH_SCO_CARKIT);

public static final int DEVICE_OUT_ALL_USB = (DEVICE_OUT_USB_ACCESSORY |

DEVICE_OUT_USB_DEVICE);

7.聲道路由：

聲音輸出的通道：

@Deprecated public static final int ROUTE_EARPIECE = (1 << 0);

@Deprecated public static final int ROUTE_SPEAKER = (1 << 1);

@Deprecated public static final int ROUTE_BLUETOOTH = (1 << 2);

@Deprecated public static final int ROUTE_BLUETOOTH_SCO = (1 << 2);

@Deprecated public static final int ROUTE_HEADSET = (1 << 3);

@Deprecated public static final int ROUTE_BLUETOOTH_A2DP = (1 << 4);

@Deprecated public static final int ROUTE_ALL = 0xFFFFFFFF;

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