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Old 22nd August 2008, 03:10 AM   #1
JinMTVT is offline JinMTVT  Canada
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Default MULTICHANNEL DSP ...using Cirrus CS497XX chip ..help

http://www.cirrus.com/en/products/pro/detail/P1117.html

this chip is very very interesting for its capability

since i have not find ANY existing product that does what i want

( decode surrround with recent formats and output multiple digital channels seperatly )

i am looking for alternatives

anyone has every played with DSP chips ?

i believe that we require licenses for decoding the different formats?

hard to obtain for personal use? expensive?

any other options ?
thanks
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Old 3rd September 2008, 02:37 PM   #2
Johnix is offline Johnix  France
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In my previous job, I had worked with this Cirrus DSP family to develop a OEM DSP board.

Frankly to say, don't think of using these chips for DIY purposes.
Maybe you'll be able to buy one of these DSP somewhere but then don't forget that hardware design covers only a few percent of the project. The big deal is software.

The available datasheet covers maybe 10% of the chip actual features and all the real interesting information to be able to develop such a decoding application is available only through NDA.

I don't even mention DTS/Dolby fees ; you need to pay them before beeing able to request documentation


What exactly are you looking for ? I think I could be of some help
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Old 4th September 2008, 03:31 AM   #3
JinMTVT is offline JinMTVT  Canada
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Ah oui ??

Well what i am really looking for is the ultimate ...
seperate digital output of surround signal chanels

what would be the best is probably to hack an Home theater receiver that already features all that is required
( matrix, volume, I/O )
and use the digital from the DSP instead of letting it pass throuh the DAC/S

Serais tres apprecie si tu pourrais m'aider sur ce probleme, car je vais avoir besoin de realiser ce fait avant que ma piece et mon "setup" de cinema-maison
soit complete .

do you want me to email you ?

thanks
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Old 5th September 2008, 05:23 PM   #4
Johnix is offline Johnix  France
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From a hardware point of viewn this DSP features :
- one spdif input (with regular 2 channels PCM or compressed content such as Dolby Digital, DTS, MPEG audio etc...)
- one 7.1 PCM input (4 IS lines)
- one 7.1 PCM output (4 IS lines)
- one 2.0 PCM output (aka downmixed content of the 7.1 output)

IS n1 is for Front Left and Front Right
IS n2 is for Surround Left and Surround Right (lateral speakers)
IS n3 is for Center and Sub
IS n4 is for Rear Left and Rear Right (back speakers)

Volume control is available from -96dB to +24dB. You can trim channels, activate matrix decoding etc...

Do you only require access to IS signals from the surround speakers ?

What is exactly your application (sorry for being curious )
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Old 6th September 2008, 02:10 AM   #5
JinMTVT is offline JinMTVT  Canada
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I would like to have access to all of the seperate digital channels once decoded from the surround signal

then use multiple DCX2496 units for Xover and split signals to send to correct destination

output that in digital from the DCX toward some superior DACS and then to amplifiers

my setup will include :

sub
front left and front right
surround left and surround right
rear center

so i need a chip with code that will permit remixing and setup without a center channel
and will work with the rear channel also

I'd also like to be able to have multiple inputs, switch
and control volume of the input sound
( total volume control wich would affect all the digital outs )


Do you believe it is possible to find a receiver that already has all the required code in it, using the CS497xx chip, and then hack it up ??
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Old 6th September 2008, 09:27 AM   #6
Johnix is offline Johnix  France
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I am not familiar with DCX2496 but I doubt it has IS inputs. You certainly need to feed him with SPDIF.

Thus you need 4 DIT chips (Texas, AKM or Cirrus) to convert the 7.1 IS decoded channels to 4 SPDIF stereo lines(ignoring center channel is just a matter of phantom mode and DSP setup, no difference on the hardware) .

The easiest way would be to open a 7.1 AVR and :
- find it's DACs (it's recommended to mod the Amp near the dacs, not close to the DSP)
- find their datasheets
- find the 4 IS lines
- design a small PCB with DIT chips
- drill the backpannel of this AVR to get all 7.1 decoded preamp digital outputs

Don't forget to check whether the volume control is analog or digital
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Old 6th September 2008, 09:28 AM   #7
Johnix is offline Johnix  France
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By the way, every single audio DSP dedicated to DSP/Dolby decoding will do the job. Not only Cirrus Logic family
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Old 7th September 2008, 03:50 AM   #8
JinMTVT is offline JinMTVT  Canada
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Hey! you do believe it is possible ?

would you help me out ?
i do not have the necessary knowledge to do such things...but i do posess the GUTS required

Do you believe that any of the current DSP chip sends out IS signal to their DACS ?

what if they use a single DAC that does multichannel conversion, will it also use multiple I2S lines?

btw please explain the meaning of :

I2S
DIT chip

if you can point me in the right direction,
i usually understand pretty quickly once i have all the required information

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Old 7th September 2008, 04:06 AM   #9
JinMTVT is offline JinMTVT  Canada
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http://p.douillard.ifrance.com/Proje...%20DCX%203.htm
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Old 7th September 2008, 06:47 PM   #10
Johnix is offline Johnix  France
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Quote:

Do you believe that any of the current DSP chip sends out IS signal to their DACS ?
I dont see the point in using a specific transmission protocol for AVR manufacturer. Thus yes it will be IS (or Left Justified maybe)

Please review the datasheet of this chip
http://focus.ti.com/docs/prod/folder...t/dit4192.html
You will understand what spdif and is are all about.

Quote:
what if they use a single DAC that does multichannel conversion, will it also use multiple I2S lines?
i think so
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