[PlanetCCRMA] multiple card synching

Michele Spinolo michele.spinolo@tin.it
Thu Feb 24 07:45:01 2005

Hi Mark,

> I spotted this text: "In the DVD player you will find a clock line and
> a data line for every channel pair. Each clock cycle means one bit of
> audio data." When I first looked at the picture I thought there might
> only be one clock since there's only one Actel FPGA. However there are
> three cables driving this chip. (The rainbow cables.) It seems likely
> to me that each cable carries it's own clock and the Actel chip is
> operating on each on independently. If true (and I'm only guessing
> about that) then each channel would be independent and unsynced.

thank you for the spot!
I mailed dvdupgrades for more clarifications

> That's disappointing but it may not be his fault. Some of the card
> manufacturers do not want to release full specs and some fo these
> features are only available if you have full specs. (Or are willing to
> use a PCI bus analyzer in a Windows box to find out what's going
> on...)

I contacted the ICE1712 mantainer and author, but I had the feeling he was
not interested adding this capabilities to ICE1712 driver.
I'll give another try!

> RME and 'cheap' don't go together very well. The low end HDSP 9652 is
> still about $600 each and it has three ADAT interfaces you wouldn't be
> using. That's not the right solution.
> Actually it may not require an HDSP which is expensive and way more
> card than you want. Possibly one of the smaller RME cards would work
> using some sort of control language. Also, there are many well
> supported 2 or 4 channel cards that have spdif inputs. Possibly one of
> them would work? I have an AP2496 but I've never investigated whether
> it can sync to spdif. If it did then 3 of them would be only
> moderately painful I think.

Yes, I know RME and cheap don't go together, unluckily!:-)
I meant cheap regarding RME cards, i.e. the cheaper RME card which could do
the trick!;-)
Is your suggestion for HDSP 9652 or HDSP 9632?

I was also thinking to build a ASRC (asynchronous sample rate converter)
based on 3 AD1896 ASRCs, all driven by the same clock: this could be used to
convert any sample rate coming for dvdupgrades board to a fixed sample rate
and all 3 s/pdifs signal should then be synched.

I have many options but all expansive or dangerous for my hardware!:-(

Thanks again!