So the question is,
Details
I have 4 sound input sources on my linux device. Here is the result of pactl list sources:
1 alsa_input.pci-0000_00_1b.0.analog-stereo module-alsa-card.c s16le 2ch 44100Hz SUSPENDED
2 alsa_input.usb-Generic_Rmoncam_HD_720P_200901010001-02.analog-stereo module-alsa-card.c s16le 2ch 48000Hz SUSPENDED
3 alsa_input.usb-Generic_Rmoncam_HD_720P_200901010001-02.analog-stereo.2 module-alsa-card.c s16le 2ch 48000Hz SUSPENDED
5 alsa_output.pci-0000_00_1b.0.hdmi-stereo.monitor module-alsa-card.c s16le 2ch 44100Hz SUSPENDED
I tried to set the source 1 alsa_input.pci-0000_00_1b.0.analog-stereo as my default source by several ways:
1.change /etc/pulse/client.conf, add following lines:
default-sink = alsa_output.pci-0000_00_1b.0.hdmi-stereo
default-source = alsa_input.pci-0000_00_1b.0.analog-stereo
2.change /etc/pulse/default.pa, add following lines:
### Make some devices default
set-default-source alsa_input.pci-0000_00_1b.0.analog-stereo
After configuration complete, I tried pulseaudio -D and reboot the device, but the config take no effect. I don't know how to list the current default source and sink, so I use following command to verify:
$> pactl load-module module-loopback latency_msec=500
$> pactl list sources short | grep RUNNING
3 alsa_input.usb-Generic_Rmoncam_HD_720P_200901010001-02.analog-stereo.2 module-alsa-card.c s16le 2ch 48000Hz RUNNING
The pactl still use my usb camera's microphone as its default source.
System Info
Linux kernel:
Linux D2-A109 4.15.0-55-generic #60-Ubuntu SMP Tue Jul 2 18:22:20 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux
PulseAudio version:
$> pulseaudio --version
11.1
Any advice is welcome!
Finally..I find it's just caused by the microphone "unplugged"... And the way to set the default source is correct.
And I find the answer of Q2."How can I list the current default source?":
$> pacmd list-sources | grep -e 'index:' -e device.string -e 'name:' -e 'available'
* index: 1
name: <alsa_input.pci-0000_00_1b.0.analog-stereo>
device.string = "front:0"
analog-input-front-mic: Front Microphone (priority 8500, latency offset 0 usec, available: no)
analog-input-rear-mic: Rear Microphone (priority 8200, latency offset 0 usec, available: yes)
analog-input-linein: Line In (priority 8100, latency offset 0 usec, available: no)
index: 2
name: <alsa_input.usb-Generic_Rmoncam_HD_720P_200901010001-02.analog-stereo>
device.string = "plug:front:1"
analog-input-mic: Microphone (priority 8700, latency offset 0 usec, available: unknown)
index: 3
name: <alsa_input.usb-Generic_Rmoncam_HD_720P_200901010001-02.analog-stereo.2>
device.string = "plug:front:2"
analog-input-mic: Microphone (priority 8700, latency offset 0 usec, available: unknown)
index: 7
name: <alsa_output.pci-0000_00_1b.0.hdmi-stereo.monitor>
device.string = "0"
Corresponding to PulseAudio wiki, The * in front of the index indicates the current default input.
To avoid someone being stupit as me, we can determine if the microphone(source) is plugged, by checking 'available' in the printing result of sources.