session sample rate vs. jack sample rate

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haszari
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I recently replace my motherboard, and the new sound hardware seems only happy running at 48kHz (ok, separate issue), whereas I used to run at 44.1kHz. I.e. when JACK starts up it uses 48kHz no matter what sample rate was specified.

The problem is that I have Ardour sessions which were recorded at 44.1kHz, and these don't play back correctly anymore (crackly and incorrect speed as far as I can tell).

So, is there a "session sample rate", and where can I set/change it? Or does it depend entirely on the JACK sample rate?

Has anyone else experienced this problem?

paul
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Joined: 2006-03-16
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there is no session sample rate. ardour uses whatever sample rate JACK is using. this is by analogy with hardware setups where there is a single master clock and everything else syncs to it - devices don't just arbitrarily choose to run at one sample rate, since that messes up their integration with everything else.

you are apparently using one of the new breed of audio interfaces that are absolutely, terminally, certifiably not designed for use to make and record music on. they cannot run at 44.1kHz, and rely on software resampling to handle anything except 48kHz. this is really unacceptable, not to mention stupid and entirely predictable behaviour by tech manufacturers.

if you really must use this device, then go into qjackctl and switch the device name from hw:0 to plughw:0. this will force ALSA (the device driver layer) to resample, and will allow you to request (and get) 44.1kHz for JACK operation.

haszari
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Thanks, that explains it. A real pity especially since the video hw on the new motherboard is much better supported in linux! Also ironic because the previous mobo sound chip was working great (realtek I think, this new one uses VIA).

I can use a different cheapo audio card I have lying around... I was hoping to use the 6 output channels of the onboard but software resampling is not a handy feature.

zrhzrh
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Joined: 2011-01-24
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Because of the same question, I Google it and discovery this page...
Finally, I found that it's couldn't work to choose "plughw:0" but to choose "hw:0,0(ALC 269 Anolog)".