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Message
From: -boggy<boggy@e...>
Date: Thu May 13 13:29:38 CEST 2004
Subject: FireWire + Re: [oc] Audio DSP PCI Card for mobile studio
Dear Mikhail, ----- Original Message -----
From: mikem@o...<mikem@o...>
To:
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...
I do not want to quarrel with you in any way whether privately or on a
discussion list. We are colleagues before all. We may differ in our
opininons, that is our right and that's it.
>
> > 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.
Purpose of fac2222m open hardware card is developing such applications,
research, learning VHDL/Verilog, learning DSP technology, etc. Audio is
not only music, IMHO. This will be audible frequencies, but not only for
human being.
> > 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?
FPGA will not be used in fac2222m audio card, because it will runs some
dsp functions faster than DSP chip.
> > >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.
I don't think that "pro audio mailing lists" is great place to learn any
thing about proffesional audio, even if you try to find answers for your
questions about music appliance of professional audio.
> > 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.
Why? Is it some common principle to make free hardware projects minor
than wery expensive closed hardware/software projects? I don't know that
this principle exist.
> 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.
Some market driven things is against some other market driven things...
Not only users will be enemy in this "war". 96kHz is standard
recommanded sample rate for broadcast, and 192kHz isn't forbiden.
> > 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.
Sorry, I don't think so.
> In fact, you can get alternative tools for SHARCs quite cheaply...
...but _not_ free like free beer :)
> > 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
This is not only one FPGA based and non free audio card available on the
market, but I don't thik that here, at opencores mailing list, is good
practice to promote non free hardware, IMHO.
> And I am not sure I understand how you are going to avoid OS,
> drivers,
> interrupts, etc.?
fac2222m have MIDI I/O.
> > > 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?
Golden fingers is expensive and this is not big problem.
Please do not forget that there are kinds of music besides commercial
and that some other kinds of music require really precise handling of
spectrum and phase.
Best regards,
-boggy
> /Mikhail
>
>
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