用BlueZ A2DP Profile播放音乐
Bluetooth支持两种Profiles来播放音乐，分别是HSP和A2DP。HSP(handset profile)是单声道的，A2DP是双声道的。本文主要介绍如何在Linux下用A2DP来播放音乐。
准备
1. 一个蓝牙耳机和一台Linux机器，Linux上默认会安装BlueZ和PulseAudio。
2. 下载一段时间较长的wav格式的音频文件，测试时会用到。
3. 确保你的蓝牙耳机和PC已经配对成功。如果没有的话，可以通过bluetooth-applet界面查找耳机并配对。
配置
1. 在/etc/pulse/default.pa，注释掉以下两行
bluetooth-discover
module-suspend-on-idle
2. 播放一段较长的wav格式音乐。
paplay 75.wav
3. 用pacmd查看该input的index，在下面的例子中index是2。
xxx@xxx:~/$ pacmd
>>> list-sink-inputs
1 sink input(s) available.
index: 2
driver:
flags:
state: RUNNING
sink: 1
volume: 0: 100% 1: 100%
0: 0.00 dB 1: 0.00 dB
balance 0.00
muted: no
current latency: 1997.28 ms
requested latency: 39.51 ms
sample spec: aLaw 2ch 44100Hz
channel map: front-left,front-right
Stereo
resample method: copy
module: 7
client: 6
properties:
media.format = "WAV (Microsoft)"
application.name = "paplay"
media.name = "75.wav"
native-protocol.peer = "UNIX socket client"
native-protocol.version = "16"
application.process.id = "6509"
application.process.user = "xxx"
application.process.host = "xxx-host"
application.process.binary = "pacat"
application.language = "en_US.utf8"
window.x11.display = ":0.0"
application.process.machine_id = "aed85c03e5ef20ad3d980db14b34d474"
application.process.session_id = "aed85c03e5ef20ad3d980db14b34d474-1283675281.437759-895707289"
module-stream-restore.id = "sink-input-by-application-name:paplay"
4. 用test-audio脚本连接耳机。在下面的例子中，耳机的地址（bdaddr）是00:16:44:21:8D:91。
cd bluez/test;
~bluez/test$ ./test-audio connect 00:16:44:21:8D:91
5. 在pulseaudio console下load module-bluetooth-device模块
>>> load-module module-bluetooth-device profile="a2dp" address="00:16:44:21:8D:91"
在上面的例子中，我们用了A2DP profile加载bluetooth模块，要使用hsp的话，替换参数成profile=”hsp”即可。
6. 在pulseaudio console下list-sink，能够显示出bluetooth的device来。在下面的例子中，index是1。
>>>list-sinks
index: 1
name:
driver:
flags: HARDWARE DECIBEL_VOLUME LATENCY
state: RUNNING
suspend cause:
priority: 9030
volume: 0: 7% 1: 7%
0: -70.57 dB 1: -70.57 dB
balance 0.00
base volume: 100%
0.00 dB
volume steps: 65537
muted: no
current latency: 44.27 ms
max request: 2 KiB
max rewind: 0 KiB
monitor source: 2
sample spec: s16le 2ch 44100Hz
channel map: front-left,front-right
Stereo
used by: 1
linked by: 1
fixed latency: 39.51 ms
card: 1
module: 16
properties:
bluetooth.protocol = "a2dp"
device.description = "DELL BH200"
device.string = "00:16:44:21:8D:91"
device.api = "bluez"
device.class = "sound"
device.bus = "bluetooth"
device.form_factor = "headset"
bluez.path = "/org/bluez/5373/hci0/dev_00_16_44_21_8D_91"
bluez.class = "0x640404"
bluez.name = "DELL BH200"
device.icon_name = "audio-headset-bluetooth"
7. 在pulseaudio console下，用move-sink-input 即可将声音导到蓝牙耳机上。
>>> move-sink-input 2 1
好了，你应该能从蓝牙耳机上听到音乐了。；-）