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Message
From: mikem at opencores.org<mikem@o...>
Date: Thu May 13 04:38:43 CEST 2004
Subject: FireWire + Re: [oc] Audio DSP PCI Card for mobile studio
Perhaps we should take it offline...> If audio stream don't circulate throughout PCI-driver-OS we don't
> have problem with long and _unpredictable_ interrupt latencies.
That's right, but this still has nothing to do with the FPGA vs. DSP
thing. Besides, if we are talking about latency during monitoring then
you don't need most of those DSP algorithms for this purpose.
> But FPGA will do faster some dsp
> functions than specialised DSP processors. And yes, this
> will be harder job for programmer... for audio applications we
> don't need this
Don't need what?
> >2. I don't want to start a flame here, but 200 kHz is a stupid
> overkill
> >driven by marketing departments. 96 kHz has plenty of margin.
> >
> I don't think so. Some people hear differences, probably therefore
> antialiasing brickwall filter at half of sample frequency have
> smaller impact to phase characteristic in high frequencies. But I
> don't hear any diference :)
This is a fact. If you don't beleive me try to find archives of the pro
audio mailing list. This issue has been beaten to death there. Those who
hear either think they hear or hear different effects.
> This is not hard work for fpga, and 192kHz is one of the number of
> sampling frequencies... will we disable it? If yes, why?
Of course 192 kHz in itself is not a hard work, but processing at this
rate is, especially processing of multiple channels. Basically, at this
point I don't really care whether it will be enabled or disabled. I am
simply saying that it doesn't make sense, especially for a free product.
Those market driven are looking for big numbers for their ads to make
people buy new hardware and make it look like whatever they have is
obsolete.
> Yes, you are right, but we don't have usable software tools for DSP
> chips freely available. This is main reason for choosing FPGA.
I am afraid this is a bad reason. FPGAs are good for fixed processing,
but not well suited for developing complex and flexible DSP algorithms.
In fact, you can get alternative tools for SHARCs quite cheaply...
> through PCI, interrupts, OS and drivers... ok, we have this in any
> shop :)
Well, I am afraid to disappoint you, but an FPGA solution exists too:
http://www.rme-audio.com/english/hammer/d9636.htm
And I am not sure I understand how you are going to avoid OS, drivers,
interrupts, etc.?
> > I was going to have PCI as well but
> >then dropped this idea since making golden fingers increases
> PCB manufacturing cost by quite a bit...
> >
> this is not big problem :)
What do you mean? You don't need PCI anymore?
/Mikhail
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