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Input resampling with PipeWire

1 January, 2025 - 13:26 — frank246

Hi and a happy new year,

not sure if this is a Qtractor or PipeWire problem, I am trying to use PipeWires resampling for recording. Here is my setup:

  • My band recordings use wav files with 48000 as a sample rate
  • I use an 48000 audio interface for playback (sc48000)
  • But my keyboard workstation for recording has a fixed sample rate using 44100 (sc44100)
  • I force PipeWires sample rate to 48000: "pw-metadata -n settings 0 clock.force-rate 48000" and start Qtractor
  • Then I import all wav files and start playback, no problem

As soon as I connect the Qtractors master input with sc44100, the the whole graph changes its speed and the playback sounds wrong. I would like to record from sc44100 with PipeWires resampling into an 48000 project.

Is this even possible or in general a bad idea? Is this a Qtractor issue or PipeWires?

Thanks a lot for some insights.

Frank

Forums: 
qtractor
1 January, 2025 - 15:16 — G3N-es

However, Qtractor allows you to import audios in 48000, even if the audio engine is working in 44100.
In options > audio > conversion type, set them to "sync best".

Test to see if the conversion is unnoticeable and does not produce artifacts or background noise.

In any case, according to my experience, the best option is always to convert them with specialized software and have a 44100 version of those audios.

Maybe someone else can shed some light on this matter.

1 January, 2025 - 16:59 — frank246

Thanks for the quick reply, but I have to create 48000 tracks for my band so I would have to resample twice.

1 January, 2025 - 17:08 — G3N-es

Work in Qtractor with PipeWire on 44100, and import the audios on 48000.
Remember:
In options > audio > conversion type, set them to "sync better".

It's a real-time conversion, which is more resource intensive, but it might do the job.

1 January, 2025 - 17:45 — G3N-es

Issuing that "forced" command prevents it.
Maybe this tool will allow you what you want:
https://github.com/pkunk/pwrate

I haven't tried it.

Here is some info on how to do it by hand
https://linuxmusicians.com/viewtopic.php?p=156371#p156371

1 Reset force:
pw-metadata -n settings 0 clock.force-rate 0

2 Default samplerate
pw-metadata -n settings 0 clock.rate <value>

3 Range value
pw-metadata -n settings 0 clock.allowed-rates [ <value1> <value2> ... ]

1 January, 2025 - 18:58 — rncbc
rncbc's picture

Frank, if you force PW to do 48k sample-rate all the way you'll certainly get batshit when interfacing with h/w devices that are stuck or only support 44k1.

You'll better check your pipewire.conf, to allow 44k1 and 48k, then pipewire/jack.conf for possibly have only 48k for jack applications and forget the metadata global trickery to 48k.

hth. cheers && happy ny.

1 January, 2025 - 19:35 — frank246

Thanks for the hints. Now I allowed both sample rates in PipeWire and force 48000 for Jack clients. As soon as I connect the sc44100 with Qtractors master input, PipeWire switches the output(!) to sc44100, too. Now I try to disable the sink (not the device) from sc44100 or disable the automatic switching from sound cards. No luck so far using search engines, any hints where to look?

1 January, 2025 - 19:54 — rncbc
rncbc's picture

now that's probably a question for you to raise at the PW fora (dead latin forum plural:))...

cheers

1 January, 2025 - 21:58 — bluebell
bluebell's picture

With the perspective of being in them I think of foris (ablative, 5th case).

2 January, 2025 - 16:24 — rncbc
rncbc's picture

dead latin aka. erudite latin...

vulgar latin is what evolved, or better said in some vernacular slang, f*cked up into the modern italian, french, castillian, (galician-)portuguese and way some more ;)

not willing to make a lecture here, just my 2c.

1 January, 2025 - 21:52 — frank246

Who would have thunk? Learning latin at school finally paid off :-)

2 January, 2025 - 12:45 — frank246

PipeWire per default allows only 48000 and claims to resample anything else: https://gitlab.freedesktop.org/pipewire/pipewire/-/wikis/Guide-Rates

It does not work for me. I removed sc44100s output from the graph and forced 48000 for Jack and Pipewire and still: as soon as I connect sc44100 with the input from qtractor, the playback speed changes. Anyway, I think this is a PipeWire problem, another DAW stumbles over sc44100, too.

2 January, 2025 - 12:52 — windowsrefund

Just throwing it out there that Ubuntu ships with a very old version. I happen to be running 1.0.5. Not sure if an upgrade is needed or if it will solve your issue but wanted to mention it.

Assuming you have super apt powers...

sudo add-apt-repository ppa:pipewire-debian/pipewire-upstream
sudo apt upgrade
sudo apt -y install pipewire
2 January, 2025 - 13:10 — frank246

Thanks, I am running the actual PipeWire 1.2.7 (and Qtractor 1.5.1) on Linux Mint using this PPA: https://launchpad.net/~savoury1/+archive/ubuntu/pipewire

2 January, 2025 - 13:54 — G3N-es

I don't know if you have it that way, but Pipewire's default fuck should be 44100.
default.clock.rate = 44100
default.clock.allowed-rates = [ 44100 48000 88200 96000 192000 ]

And Jack 48000

Thus, everything will be converted to 44100 when entering or leaving, and allows Jack to work internally at 48000.
But that is just what I have believed to understand about PW, maybe I am wrong.

2 January, 2025 - 15:55 — frank246

Interesting thought, I gave it a test:

update: id:0 key:'log.level' value:'2' type:''
update: id:0 key:'clock.rate' value:'44100' type:''
update: id:0 key:'clock.allowed-rates' value:'[ 44100, 48000 ]' type:''
update: id:0 key:'clock.quantum' value:'1024' type:''
update: id:0 key:'clock.min-quantum' value:'32' type:''
update: id:0 key:'clock.max-quantum' value:'2048' type:''
update: id:0 key:'clock.force-quantum' value:'0' type:''
update: id:0 key:'clock.force-rate' value:'48000' type:''

It is as strange as frustrating: as soon as I connect sc44100 the speed changes and when I disconnect everything goes back to normal.

2 January, 2025 - 16:11 — rncbc
rncbc's picture

while you're at it,

please try asking on the oftc pipewire irc, there might be well more knowledge people in there ;)

once again, cheers

2 January, 2025 - 17:24 — frank246

Yeah, I joined their matrix room, with little success so far.

2 January, 2025 - 21:26 — G3N-es

Try Audacity in ALSA mode.
To keep the connections open you have to press pause and record.
If it works, use Audacity (or another alsa application) as an intermediary converter.

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