[LAU] pros and cons for audio backends of 2nd sound card

[david]

On 2/8/21 1:58 PM, Len Ovens wrote:
> On Mon, 8 Feb 2021, Athanasios Silis wrote:
>
>> Which audio adapter do you use to use a 2ndary sound card in jack?
>> 1.jacl_load audioadapter
>> 2. alsa_[in | out] ?
>> 3. zita_[a2j | j2a] ?
>
> zita-ajbridge
>
>> why do you use the one you use? What are its advantages ? Have you
>> identified or do you know of any disadvantages for each of the above ?
>
> alsa_in/out must run at the same parameters as jack, takes more cpu.
>
> I stay away from internals because the internal can bring jack down. I 
> don't know if you can run more than one internal at a time.
>
> So I use zita-ajbridge because it uses less cpu, sounds good, allows 
> the second card to run at whatever SR it supports, Allows hard sync if 
> the cards are synced (there will be an offset), allows setup of more 
> than one extra device. I can handle USB device (un)plug on the fly 
> with other code.
>
> All of these things are important because I deploy the setup where I 
> do not know what the user will try (some users have 3 or 4 of those 
> horrible USB mics).
>
>> Do you have preferred options to minimize xruns ?
>
> It seems that if the jack master is stable that makes a lot of 
> difference. Other than that... the same as for any jack master. 
> prioritize irq handler(s) (jack master should probably be highest), 
> don't share the irq with other stuff, don't share the USB bus with 
> other stuff, raise buffer size as required.

My main laptop setup is to have everything going through JACK to use the 
external USB soundcard, with PulseAudio set to use JACK as its back end. 
I have the built-in audio disabled. I found that much simpler. The 
external card feeds an external mixer and amp, the card has hardware 
monitoring and a headphone jack. And a lovely volume control wheel. :)

The old Intel Atom-based netbook is for playing music/videos, so it just 
uses PulseAudio with the built-in audio hardware.

The desktop system has no audio - the motherboard audio has never worked 
and the few times I tried the USB sound card on it, I couldn't get that 
working, either. So I removed all the pro audio stuff from it, it just 
has Debian's default PulseAudio setup on it.

-- 
David W. Jones
gnome at hawaii.rr.com
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