pulseaudio之pacmd命令

如何使用pacmd来选择输出设备
(由HDMI输出或LineOut输出)

如何设置输出设备

來源: PulseAudio/Examples

Set the default output source
先使用pacmd list-sinks-inputs，找出有那些sink index
再使用pacmd set-default-sink 0 或 pacmd set-default-sink 名字(name)
1 2
# pacmd set-default-sink 0 # pacmd set-default-sink alsa_output.pci-0000_00_1f.3.iec958-stereo

# pacmd list-sinks-inputs

1 sink input(s) available.index: 0driver: <protocol-native.c>flags: state: DRAINEDsink: 0 <alsa_output.pci-0000_00_1f.3.iec958-stereo>volume: mono: 65536 / 100% / 0.00 dBbalance 0.00muted: nocurrent latency: 0.00 msrequested latency: 125.00 mssample spec: s16le 1ch 8000Hzchannel map: monoMonoresample method: speex-float-1module: 11client: 0 <ALSA plug-in [nvr]>properties:media.name = "ALSA Playback"application.name = "ALSA plug-in [nvr]"native-protocol.peer = "UNIX socket client"native-protocol.version = "30"application.process.id = "823"application.process.user = "root"application.process.host = "localhost.localdomain"application.process.binary = "nvr"application.language = "en_US.UTF-8"window.x11.display = ":0"application.process.machine_id = "591ae69f060143d296b3ab64faea41e1"module-stream-restore.id = "sink-input-by-application-name:ALSA plug-in [nvr]"

Pulseaudio

What Is PulseAudio?
PulseAudio is a sound system for POSIX OSes, meaning that it is a proxy for your sound applications.

來源：PulseAudio

pulseaudio為一個audio service
- OSS sink表示输出音源部分
  从PulseAudio要转到声音设备的介面
- OSS source表示输入音源部分
  任何需要进入到PulseAudio的声音，都会经由source介面

PulseAudio服务软件架构
- 将来自各个不同的音源转到正确的窗口
- 针对不同的应用程式做音量的调整
- 接受多个音源的输入（source）或是输出（sink）

command

pactl命令可以修改伺服器的设置以及配置，但pactl命令仅限于局限的范围
若要完整的功能，就必須要回归到最基本的指令pacmd,通过pacmd指令
才可以完全的控制PulseAudio的服务核心。

fedora24提供下列指令
- pulseaudio - The PulseAudio Sound System
- pactl - Control a running PulseAudio sound server
- pacmd - Reconfigure a PulseAudio sound server during runtime

# pactl info

Server String: /tmp/pulse-9S2nAsoQttCY/native
Library Protocol Version: 30
Server Protocol Version: 30
Is Local: yes
Client Index: 8
Tile Size: 65472
User Name: root
Host Name: localhost.localdomain
Server Name: pulseaudio
Server Version: 8.0
Default Sample Specification: s16le 2ch 44100Hz
Default Channel Map: front-left,front-right
Default Sink: alsa_output.pci-0000_00_1f.3.iec958-stereo
Default Source: alsa_input.pci-0000_00_1f.3.analog-stereo
Cookie: fca1:256c

# pactl list
查看周边，可知目前只有1个source

Sink #0State: RUNNINGName: alsa_output.pci-0000_00_1f.3.iec958-stereoDescription: Built-in Audio Digital Stereo (IEC958)Driver: module-alsa-card.cSample Specification: s16le 2ch 48000HzChannel Map: front-left,front-rightOwner Module: 6Mute: yesVolume: front-left: 65536 / 100% / 0.00 dB,   front-right: 65536 / 100% / 0.00 dBbalance 0.00
Base Volume: 65536 / 100% / 0.00 dB

ALSA