[pulseaudio-discuss] Recipe: recording sound card input and output
Hi folks, I just spent a while figuring out how to solve a particular need and want to save it in the mailing list for posterity. I'm an amateur radio operator, and we make extensive use of external sound cards for interfacing computers with radios for digital communication modes. I was experiencing a problem where I really wanted to record received audio (RX) to the left channel of a file, and transmitted audio (TX) to the right channel. Doing so would let me hear exactly what the modem program heard and sent. After much fussing, I found an arrangement that worked: set up a null-sink to represent the rx-tx stream I wanted, then use two loopbacks, one each for RX and TX. Once that was set up, recording the file was simple. # BurrBrown chipset used in SignaLink USB SOUND_CARD="BurrBrown" RADIO_RX=$(pacmd list-sources | egrep "input.*$SOUND_CARD" | grep -oP "<\K[^ >]+") RADIO_TX=$(pacmd list-sources | egrep "output.*$SOUND_CARD.*monitor" | grep -oP "<\K[^ >]+") pactl load-module module-null-sink sink_name=rxtx sink_properties=device.description=RXTX pactl load-module module-loopback source=$RADIO_RX sink=rxtx channels=1 channel_map=left pactl load-module module-loopback source=$RADIO_TX sink=rxtx channels=1 channel_map=right [image: Radio Interface Source_Sink.jpg] Hopefully this will help someone in the future looking to record both the input and output to a sound card! Chris Keller, K0SWE
Re: [pulseaudio-discuss] Start condition failed - ConditionUser=!root not met
Hi Colin! On Thu, 2021-10-14 at 13:18 +0100, Colin Guthrie wrote: > Tanu Kaskinen wrote on 13/10/2021 20:25: > > On Wed, 2021-10-13 at 14:51 +, Joel wrote: > > > Tanu - > > > > > > Thank you. I made the changes you suggested (removed > > > pulseaudio.socket from two locations where I found the file: > > > /etc/systemd/system/and /etc/systemd/system/sockets.targets.wants. > > > In the file pulseaudio.service, I commented out the lines > > > "Requires=pulseaudio.socket"; "ConditionUser=!root" and > > > "Also=pulseaudio.socket". Please note that there also two > > > occurrences of this file: /etc/systemd/system/and > > > /etc/systemd/system/multi-user.targets.wants. Perhaps the second > > > occurrences are system-generated. > > > > > > I then had sound from the web browser! VLC was still providing sound > > > as before (but I gather not using pulsesaudio). After logging out > > > then logging back in (not rebooting), there was no web browser sound > > > and a new error: Failed to load module "module-x11-publish". This > > > also occurred after rebooting and booting from a cold start. After > > > the reboot, a further error arose: Error opening PCM device front:0: > > > Device or resource busy. Also, the /var/run/.pulse cookie does > > > exist. The systemctl status reports in full are at > > > https://susepaste.org/99540079 . I'm unable to determine what I did > > > to cause these errors. > > > > The module-x11-publish error is probably caused by > > /etc/xdg/autostart/pulseaudio.desktop, which is loaded on login, > > causing /usr/bin/start-pulseaudio-x11 to be run. You could try removing > > the pulseaudio.desktop file (take a backup if you want). You shouldn't > > lose any essential functionality by doing that (and since PulseAudio > > was unable to connect to X11, whatever PulseAudio wanted to do didn't > > succeed anyway). > > > > If you see "Device or resource busy", something else is using the ALSA > > device. You can check with "lsof /dev/snd/*" what programs are using > > the ALSA devices. > > Forgive my ignorance since it's been *years* since I did any PA hacking > (just a drive by message on the list as I clicked on the folder in my > email client!) but do you really want your system-wide PA instance > running as root (that's what the systemd unit files suggests!) > > Wouldn't you want a User=pulse in there in the system unit (and make > sure the user pulse can access the audio devices via suitable ACLs/group > ownerships) PulseAudio does the user switch from root to pulse by itself, I don't know if PulseAudio can handle it if you start it directly as the pulse user. > It would be fine to have a system-wide pulseaudio.socket here that > started up the system-wide pulseaudio.service? Yes, it would be fine, if you configure it right. > Or have things changed so much that the system-wide pulseaudio instance > no longer runs as the pulse user? Nope, I don't think there has been much changes to the system-wide mode at all :) -- Tanu
Re: [pulseaudio-discuss] Start condition failed - ConditionUser=!root not met
Tanu Kaskinen wrote on 13/10/2021 20:25: On Wed, 2021-10-13 at 14:51 +, Joel wrote: Tanu - Thank you. I made the changes you suggested (removed pulseaudio.socket from two locations where I found the file: /etc/systemd/system/and /etc/systemd/system/sockets.targets.wants. In the file pulseaudio.service, I commented out the lines "Requires=pulseaudio.socket"; "ConditionUser=!root" and "Also=pulseaudio.socket". Please note that there also two occurrences of this file: /etc/systemd/system/and /etc/systemd/system/multi-user.targets.wants. Perhaps the second occurrences are system-generated. I then had sound from the web browser! VLC was still providing sound as before (but I gather not using pulsesaudio). After logging out then logging back in (not rebooting), there was no web browser sound and a new error: Failed to load module "module-x11-publish". This also occurred after rebooting and booting from a cold start. After the reboot, a further error arose: Error opening PCM device front:0: Device or resource busy. Also, the /var/run/.pulse cookie does exist. The systemctl status reports in full are at https://susepaste.org/99540079 . I'm unable to determine what I did to cause these errors. The module-x11-publish error is probably caused by /etc/xdg/autostart/pulseaudio.desktop, which is loaded on login, causing /usr/bin/start-pulseaudio-x11 to be run. You could try removing the pulseaudio.desktop file (take a backup if you want). You shouldn't lose any essential functionality by doing that (and since PulseAudio was unable to connect to X11, whatever PulseAudio wanted to do didn't succeed anyway). If you see "Device or resource busy", something else is using the ALSA device. You can check with "lsof /dev/snd/*" what programs are using the ALSA devices. Forgive my ignorance since it's been *years* since I did any PA hacking (just a drive by message on the list as I clicked on the folder in my email client!) but do you really want your system-wide PA instance running as root (that's what the systemd unit files suggests!) Wouldn't you want a User=pulse in there in the system unit (and make sure the user pulse can access the audio devices via suitable ACLs/group ownerships) It would be fine to have a system-wide pulseaudio.socket here that started up the system-wide pulseaudio.service? Or have things changed so much that the system-wide pulseaudio instance no longer runs as the pulse user? Col
