True, the patent and JAES article are as usual not the full story. The only
problem with the second user stuff is whether the thing itself is working
properly. Access to a test rig would be useful - never used the 363 but
I've had a lot of experience with the earlier 361 unit which uses the CAT
22 Dolby A card. We had the full test rig that you interposed between the
card and the main body of the 361. I found it essential to run each card
through test at least a couple of times a year - not that there were a lot
of faults, but there were some and with the devices being thirty years
old..... Dolby ran a wonderful service where you phoned up, told them you
had a faulty card and they would ship you a replacement without waiting for
your one to arrive back with them and at no cost to you apart from
post. Even in York this meant that the most you were without a channel was
24 hours - I can remember cycling to York Railway Station to pick up units
direct off the train! In London the turn round was a couple of hours and
the courier would take the faulty unit back so not even the cost of return
postage (or rail freight). Amazing trust and service, wonder if anyone does
that for anything these days!
One possibility would be to use Spice to model the circuit and just process
the sound files through the model. Slower than a directly written program,
but probably usable for archival work.
Dave
On 30 April 2013 08:55, Eric Benjamin <eb...@pacbell.net> wrote:
> On 30 Apr 2013, at 04:56, David Pickett wrote:
>
> > A standalone Windows app that would decode Dolby-A encoded wavefiles and
> output
> >a restored non-Dolby 24-bit wavefile would be most useful. I have several
> >recordings that I have had transfer to hi-res files still in Dolby-A
> format.
> > ... even if such a program were command line only and needed to be left
> >overnight to cook!
>
> Being a fan of doing things the easy way, I'd recommend just buying a Dolby
> Model 363 NR unit which does both A type and SR. At any point in time
> there are
> typically a dozen or so available on Ebay for prices in the range of $150
> to
> $300. It's difficult to model something like Dolby NR in DSP because the
> algorithm is defined by a circuit. You would need to very carefully
> benchmark a
> working decoder in any case because neither the patent or the JAES article
> really tell you how to do it.
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--
As of 1st October 2012, I have retired from the University, so this
disclaimer is redundant....
These are my own views and may or may not be shared by my employer
Dave Malham
Ex-Music Research Centre
Department of Music
The University of York
Heslington
York YO10 5DD
UK
'Ambisonics - Component Imaging for Audio'
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