Subject: Re: [linux-audio-dev] BruteFIR + jack = crackling noise?
From: Martijn Sipkema (msipkema_AT_sipkema-digital.com)
Date: Tue Feb 25 2003 - 18:10:43 EET
[...]
> I'm a newbie to LAD, but I have some years of experience of developing
> and using a system similar to JACK for routing blocks of samples to
> DSP modules of a digital satellite control receiver and transmitter
> system running on Solaris (we are talking about some megasamples per
> second here).
>
> IMHO, the only sensible way for a system like JACK to operate is by
> using a constant blocksize.
IMHO the hardware should dictate the blocksize. For most audio
interfaces this will be constant. For some it is not.
> Anyway, if you have several HW interfaces
> each using their own blocksize or interrupt frequency then this is the
> only sane option.
This is another issue. JACK doesn't not support more than one device
nor should it. If an application wants to use more than one device the
extra buffering and possibly synchronisation is up the the application.
> If this means an extra buffering layer, then so be it. That's the
> price you pay for sloppy HW design.
I really don't think that hardware that doesn't provide a constant
number of samples per interrupt is sloppy HW design and I think
the audio framework and applications should handle this without
adding unnecessary buffering.
> BTW, can JACK handle several HW interface using different blocksizes
> at a time (assuming sample frequencies are coherent) ?
No, but you could run several instances of JACK.
--ms
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