android 耳机系统笔记2 --多媒体设备各种状态

frameworks\base\include\media\AudioSystem.h中定义
===================================================================
device:
enum audio_devices {
        // output devices
        DEVICE_OUT_EARPIECE = 0x1,
        DEVICE_OUT_SPEAKER = 0x2,
        DEVICE_OUT_WIRED_HEADSET = 0x4,
        DEVICE_OUT_WIRED_HEADPHONE = 0x8,
        DEVICE_OUT_BLUETOOTH_SCO = 0x10,
        DEVICE_OUT_BLUETOOTH_SCO_HEADSET = 0x20,
        DEVICE_OUT_BLUETOOTH_SCO_CARKIT = 0x40,
        DEVICE_OUT_BLUETOOTH_A2DP = 0x80,
        DEVICE_OUT_BLUETOOTH_A2DP_HEADPHONES = 0x100,
        DEVICE_OUT_BLUETOOTH_A2DP_SPEAKER = 0x200,
        DEVICE_OUT_AUX_DIGITAL = 0x400,
        DEVICE_OUT_DEFAULT = 0x8000,
        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_DEFAULT),
        DEVICE_OUT_ALL_A2DP = (DEVICE_OUT_BLUETOOTH_A2DP | DEVICE_OUT_BLUETOOTH_A2DP_HEADPHONES |
                DEVICE_OUT_BLUETOOTH_A2DP_SPEAKER),

        // input devices
        DEVICE_IN_COMMUNICATION = 0x10000,
        DEVICE_IN_AMBIENT = 0x20000,
        DEVICE_IN_BUILTIN_MIC = 0x40000,
        DEVICE_IN_BLUETOOTH_SCO_HEADSET = 0x80000,
        DEVICE_IN_WIRED_HEADSET = 0x100000,
        DEVICE_IN_AUX_DIGITAL = 0x200000,
        DEVICE_IN_VOICE_CALL = 0x400000,
        DEVICE_IN_BACK_MIC = 0x800000,
        DEVICE_IN_DEFAULT = 0x80000000,

        DEVICE_IN_ALL = (DEVICE_IN_COMMUNICATION | DEVICE_IN_AMBIENT | DEVICE_IN_BUILTIN_MIC |
                DEVICE_IN_BLUETOOTH_SCO_HEADSET | DEVICE_IN_WIRED_HEADSET | DEVICE_IN_AUX_DIGITAL |
                DEVICE_IN_VOICE_CALL | DEVICE_IN_BACK_MIC | DEVICE_IN_DEFAULT)
    };

====================================================================
mode:
enum audio_mode {
        MODE_INVALID = -2,
        MODE_CURRENT = -1,
        MODE_NORMAL = 0,
        MODE_RINGTONE,
        MODE_IN_CALL,
        NUM_MODES  // not a valid entry, denotes end-of-list
    };
=====================================================================
channel:
enum audio_channels {
        // output channels
        CHANNEL_OUT_FRONT_LEFT = 0x4,
        CHANNEL_OUT_FRONT_RIGHT = 0x8,
        CHANNEL_OUT_FRONT_CENTER = 0x10,
        CHANNEL_OUT_LOW_FREQUENCY = 0x20,
        CHANNEL_OUT_BACK_LEFT = 0x40,
        CHANNEL_OUT_BACK_RIGHT = 0x80,
        CHANNEL_OUT_FRONT_LEFT_OF_CENTER = 0x100,
        CHANNEL_OUT_FRONT_RIGHT_OF_CENTER = 0x200,
        CHANNEL_OUT_BACK_CENTER = 0x400,
        CHANNEL_OUT_MONO = CHANNEL_OUT_FRONT_LEFT,
        CHANNEL_OUT_STEREO = (CHANNEL_OUT_FRONT_LEFT | CHANNEL_OUT_FRONT_RIGHT),
        CHANNEL_OUT_QUAD = (CHANNEL_OUT_FRONT_LEFT | CHANNEL_OUT_FRONT_RIGHT |
                CHANNEL_OUT_BACK_LEFT | CHANNEL_OUT_BACK_RIGHT),
        CHANNEL_OUT_SURROUND = (CHANNEL_OUT_FRONT_LEFT | CHANNEL_OUT_FRONT_RIGHT |
                CHANNEL_OUT_FRONT_CENTER | CHANNEL_OUT_BACK_CENTER),
        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),
        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),
        CHANNEL_OUT_ALL = (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 | CHANNEL_OUT_BACK_CENTER),

        // input channels
        CHANNEL_IN_LEFT = 0x4,
        CHANNEL_IN_RIGHT = 0x8,
        CHANNEL_IN_FRONT = 0x10,
        CHANNEL_IN_BACK = 0x20,
        CHANNEL_IN_LEFT_PROCESSED = 0x40,
        CHANNEL_IN_RIGHT_PROCESSED = 0x80,
        CHANNEL_IN_FRONT_PROCESSED = 0x100,
        CHANNEL_IN_BACK_PROCESSED = 0x200,
        CHANNEL_IN_PRESSURE = 0x400,
        CHANNEL_IN_X_AXIS = 0x800,
        CHANNEL_IN_Y_AXIS = 0x1000,
        CHANNEL_IN_Z_AXIS = 0x2000,
        CHANNEL_IN_VOICE_UPLINK = 0x4000,
        CHANNEL_IN_VOICE_DNLINK = 0x8000,
        CHANNEL_IN_MONO = CHANNEL_IN_FRONT,
        CHANNEL_IN_STEREO = (CHANNEL_IN_LEFT | CHANNEL_IN_RIGHT),
        CHANNEL_IN_ALL = (CHANNEL_IN_LEFT | CHANNEL_IN_RIGHT | CHANNEL_IN_FRONT | CHANNEL_IN_BACK|
                CHANNEL_IN_LEFT_PROCESSED | CHANNEL_IN_RIGHT_PROCESSED | CHANNEL_IN_FRONT_PROCESSED | CHANNEL_IN_BACK_PROCESSED|
                CHANNEL_IN_PRESSURE | CHANNEL_IN_X_AXIS | CHANNEL_IN_Y_AXIS | CHANNEL_IN_Z_AXIS |
                CHANNEL_IN_VOICE_UPLINK | CHANNEL_IN_VOICE_DNLINK)
    };

=====================================================================
connection_state:
enum device_connection_state {
        DEVICE_STATE_UNAVAILABLE,
        DEVICE_STATE_AVAILABLE,
        NUM_DEVICE_STATES
    };