"Dolby Volume" sound level processor...DIY?

[Paul G.]

I was trying to make my own sound level control circuit (which I
did) and in the process discovered that Dolby has a very good sounding
sound processor
(http://www.dolby.com/consumer/technology/dolby-volume-demo.html) that
is often incorporated into several digital media control units, and is
also built into some CirrusLogic audio DSP chips
(CS48DV2A-CQZ,CS48DV2B-CQZ,CS48DV6B-CQZ,CS48DV2A-DQZ). There are also
evaluation boards (CRD48DV2-USB 2ch., CDB48DV6-USB 6ch.). The
evaluation boards looked very interesting, since they had analog
inputs and outputs. The ADC and DAC functions were built into the
evaluation boards. The other chips above, accept digital I/O.
Apart from the rather high cost for the evaluation boards ($250-300)
they seem difficult to obtain, it looks like these are special factory
orders, with minimum 26 week delivery times. The chips aren't all that
costly 10-20$, but require orders of 2000 min, with poor delivery
dates. The chips seem a messy solution, since they require a lot of
supporting hardware and software.
I was looking for an analog box to go between a digital cable box
and a TV set. The inconsistencies of loudness between channels and
programs was driving me nuts - I couldn't hear soft conversations in
movies, and was blasted out of my chair by commercials. Even though
the cable box provided some degree of compression, it was not enough
to overcome the "mucking about" some channels have done to their
audio.
My home-made kludge allows me to apply a +10db extra gain for low
levels, and a 10db attenuation for loud levels. Both have threshold
levels that I can set from -60dbv to +20dbv. This doesn't have any of
the whizzy frequency bands and masking compensation that the Dolby
Volume processor has. It does finally let me watch the old movies
without waking up half the neighborhood.
I'm intrigued by the Dolby Volume..... has anyone tried one of
these? It's being added to some of the more recent AV products (i.e.,
Arcam AVR600, Harmon Kardon AVR1600). I don't see any products that
are cheap and simple, something that you could buy for less than $50
and stick it between your sound source and stereo in analog form.
There is probably a reasonable market for such a thing, I have heard
many complaints about the excessive variation in sound levels from TV
stations.
I did find this unit available in the UK for 60 pounds:
http://ukhdmi.com/CYP_DCT_6_Dolby_Volume_Processor_QQ101641 but it
seems impossibly small to house all the circuitry required!
There is other competition to Dolby Volume, that is: "SRS
Truvolume", and "Audyssey Dynamic Volume". All use DSP. I couldn't
find any sources that would allow me to do a DIY circuit using them,
other than purchasing another impossibly small unit like the above
one, but using "Truvolume", from the same manufacturer.
Grrr..... electronic technician's dilemma.... pay $100-150 for
pre-packaged unit, or build it myself for about 1/2 the cost in parts,
several hundred hours of fiddling, months of delivery delays.....
How difficult are these audio DSP's to use and breadboard?

Paul G.

 

[Paul G.]

Paul G. wrote:



There are TAS3002/TAS3004 from TI, with the integrated audio CODECs.
Very cheap and simple to use; ideal for the applications like
tone/volume controls, DRC and equalization. Unfortunately NRND.
The only problem with breadboarding is QFP with 0.5mm pitch.

DIP adapters seem to be a lot cheaper now than some years ago...I
found these: http://www.ezprototypes.com/DipAdaptersMain.php QFP48pin
0.5mm pitch, $8.75 each. I was expecting prices around 50-100$.
Soldering them isn't all that hard, especially if you have some thin
solder-wick. The physical part of the circuit is a bit awkward, but
I'm concerned about the software.
The Cirruslogic chips with "Dolby Volume" (CS48DV2B) require
software to be run at each powerup, I wonder how co-operative Cirrus
is with the DIY crowd.... The last thing I want is to be writing my
own code for one of those beasts. I've done older PLD's before, I'm
not so sure about the DSP's.

Paul G.

 

[Frank Buss]

DIP adapters seem to be a lot cheaper now than some years ago...I
found these: http://www.ezprototypes.com/DipAdaptersMain.php QFP48pin
0.5mm pitch, $8.75 each. I was expecting prices around 50-100$.

Why did you expect such high prices? It is just a small PCB. If you create
the layout yourself and order it from http://www.olimex.com/pcb/ or other
PCB companies, it would be the same low price.

You can even get multi-adpaters for QFP, TQFP, for 0.5 mm and 0.65 mm
pitch, from 16 to 80 leads, all in one adapter, for $1,99 from eBay:

http://tinyurl.com/qfp-44-80

 

[Paul G.]

In the old day you could make a nice audio AGC with some J-FET and detector.
Or you could send the audio via a Linux PC and use my xpequ audio processor:
http://panteltje.com/panteltje/xpequ/index.html
It has an AGC function.
BUT is has latency of course, so the audio will be a little late
The analog J-FET system looks better for you, you could improve linearity
by using some Gilbert cell or whatever it is called (controlled diff ammp).
Use silicon transistors LOL.
hehe

It was kinda interesting to see if you can actually buy a simple
box (analog in/out) that employs "Dolby Volume", or "SRS Truvolume",
or any of the decent DSP based volume regulators. I can only find one,
that is a "DCT-6S (newer number is AU-D6S)", manufactured by Cypress
Technology.
http://www.turbosat.com/products/CYP-AU%2dD6S-SRS-TruVolume-Audio-Control-Processor.html
Cost is around 130$, and the box is amazingly small. It needs an
external 5v supply.
What I find unusual, is that you can't seem to get this product in
North America! Oversees companies won't ship it here. Some of Cypress
technology's products are available in U.S.A., but not their line of
"CYP" products which include the sound processor, analog-digital
converters, etc, all in their tiny little boxes.
It seems that Dolby and SRS are licensing their technologies to
large companies (not the DIY crowd), and if you want to have the
features of Dolby Volume or SRS Truvolume, you need to buy a very
expensive TV or media control center. In order to buy chips from
Freescale, CirrusLogic that have Dolby Volume or Truvolume, it seems
you need to be a licensee.
So all this hoopla about the great volume processing is of little
use to the guy who does stuff on the cheap, or by DIY. My paranoia
says its a conspiracy to fleece customers or high-end buyers, my
rational thinking says there isn't a sufficient market in North
America for a cheap and simple TV volume adjuster that uses Truvolume,
Dolby Volume, or Audyssey Dynamic Volume.
There is a product called "Terk VR1 Automatic TV Volume Controller"
which has a similiar function, but it doesn't use a well known
methodology for controlling volume. It costs $25-40, and it's
available from amazon.com. It claims to use DSP, but I couldn't find
any details about it.
The lack of internet discussion or comparisons on the above units
suggests to me that very few people seem to care - there isn't a big
market for this stuff, and the folks who make TV commercials have an
incredible arsenal of techniques that can outwit any effort to control
the volume.


Paul G.

 

[Paul G.]

On Fri, 30 Oct 2009 11:30:40 GMT, Jan Panteltje

......[stuff deleted].......

So this is all about "closing the analog loophole" (type it in google without the quotes),
preventing people from making high quality recordings via analog outputs.

That is why you can only buy those things with integrated sound processor.
It is insane, because anyone with just the tiniest bit of electronics knowledge can tap
the analog sound from the speakers, but this is the world we live in.
They do it with the video part too, that is why we have HDMI, not because that gives a better picture, it does not.

So, anyways, tap the sound that goes to the speaker amps, use a simple analog AGC, for 5.1 surround audio 5 J-FETS?
and be done with it.
Do not dance to Hollywood's tune.

Did some digging around, following your lead. It appears to be as
you say.... a vast "conspiracy" to do away with analog, presumably to
put a damper on piracy. Once you get away from North America, it seems
that it is much easier to get your hands on devices that can deal with
the analog signals. As media processing matures, I can see that the
necessity for control, security, interactive programming, etc., is
going to lead to complex media streams. It will probably turn into
another "digital tower of Babel" like Windows. In the future, media
hacking may a field day, and listening to a song could make your
digital house fall apart!
Luckily, it's going to be a while before speakers can only run on a
digital data stream!
In the meantime, I'm still working on an all analog solution.
Setting attack & release times seems to be very much an artform. the
range of audio from various TV stations and programs is SO variant, it
becomes very difficult to design a one-size-fits-all solution that
doesn't have wierd artifacts like "noise breathing". Some stations
have expanded the audio range, some have applied squelch at low
volumes, some have already compressed the hell out of the signals, all
kinds of crazy stuff. Some have applied some very artful processing
that keeps the levels reasonable, but has sounds specially designed to
be disturbing i.e., baby squalling, shrill wife sounds, male buddy
talk, fast talking insane car salesmen, etc.
There are those supposedly lucky people who claim to be able to
ignore things like commercials. But commercials are a form of
propaganda, human beings CANNOT avoid being influenced by them, no
matter how much the victims claim to say otherwise. You throw enogh
crap at a wall, it will eventually stick. The science of propaganda
was refined during the course of two world wars and a cold war.....
and advertising (and of course, politics) has made good use of those
techniques. A number of those techniques make use of audio processing
to enhance "suggestibility".
No amount of digital, analog, or mental processing will reduce
those techniques.... I need to hit the "off" button. My paranoia has
run off-scale!

Paul G.