5.1 decoder

[soundNERD]

First, I'll try and design a PCB and post it here.

Second, what are you talking about by paying dolby?

-Mike

 

[koolscooby]

A project with the CS429x chip sounds very interesting, but there is only one problem: Where do we get the software? I believe this is what you need to pay Dolby big licensing fees for, right?

As for pcbs and soldering, search for "PLCC socket" on digikey 😉

😱 😱 awesome!!! 🙂 😎 ,thanks 🙂))

Well i always wondered about the dolby digital licensing etc... but the chip includes all functinos needed, 24 bit DSP, 3d outputs, etc... [decoder], what not

 

[ojg]

Well i always wondered about the dolby digital licensing etc... but the chip includes all functinos needed, 24 bit DSP, 3d outputs, etc... [decoder], what not

I'm sorry for ruining the party, but the first paragraph and figure of this app-note says it all. It is only a RAM-based DSP that is
capable of doing DTS/AC3 and such. The software must be downloaded from an external ROM or microcontroller. Now where do we get the code to go in that ROM? I'm afraid Cirrus would want some money for that.

 

[kmt]

Yup, You're right. That was exactly the problem I encountered when I tried to build up a 5.1 surround decoder as a dissertation work. AFAIK the CS49xxx chips need to be programmed before they can decode Dolby. They're not a hardware solution. One upcoming hardware solution I know of are the MAS3529 chips by Micronas / Intermetall. But they don't sell any without having seen a Dolby license. I tried to contact Dolby about that - they even didn't answer. So probably the best solution could be to "cannibalize" an old Surround Amp...

Concerning the soldering "problem" of the SMD chips, I normally do it the following way:

1. make an adapter PCB (e.g. SSOP-> DIL)

2. solder the whole pins on one side of the chip together to one
big spot.

3. use desoldering wire (?!? desoldering cord - however) to remove the bridges between the pins.

The result is a perfect soldered SSOP (or whatever) chip. I tried it many times, it's working perfectly right.

With Christmas and New Years greetings

Kai Markus Tegtmeier

 

[koolscooby]

I'm sorry for ruining the party, but the first paragraph and figure of this app-note says it all. It is only a RAM-based DSP that is
capable of doing DTS/AC3 and such. The software must be downloaded from an external ROM or microcontroller. Now where do we get the code to go in that ROM? I'm afraid Cirrus would want some money for that.

wow that is really *******ed up heh, i should have read more, but at least i'll have one hehehe 🙂... so i guess the best solution is to rip apart old dolby decoders

 

[soundNERD]

OK, now I am confused,

So, do I need to somehow load software onto the chips used for the 2 channel decoder at sound.au?

I can't just solder them into the circuit and they work?

-Mike

 

[fr0st]

2 channel Dac's are hardware based so you need no external rom.
Dolby Digital is a specialise digital format designed by dolby, hence they need money from people to be able to decode it.
I'm guessing CS42518/28 wouldn't do the same job?

Do we know anyone with a passion for DSP algorithims?
I'll do a bit of research but as yet my assembler isn't very good (yet alone any work with dedicated DSP's).
Checking the dolby patents would be a start.

 

[koolscooby]

2 channel Dac's are hardware based so you need no external rom.
Dolby Digital is a specialise digital format designed by dolby, hence they need money from people to be able to decode it.
I'm guessing CS42518/28 wouldn't do the same job?

Do we know anyone with a passion for DSP algorithims?
I'll do a bit of research but as yet my assembler isn't very good (yet alone any work with dedicated DSP's).
Checking the dolby patents would be a start.

I smell a huge DIY project ... 🙂 I think that if we got people that know sound algorithms and DSP control stuff, and hopefully the same person knows assembly, we could play around with that 😉... and even develop a publicly avalable software for it, but for "education", so nothing is illegal, reverse engineering is acceptable as long as findings are used for learning... [i think 🙂], and something is only illegal if you cant get away with it....
i have some time i'll research some patent info and paste it here if i come up with any luck

peace out
have a great new years to everyone! 🙂

 

[Benjlv]

now avoiding illegal issues...would it be possible to extract the software from the rom?

 

[koolscooby]

now avoiding illegal issues...would it be possible to extract the software from the rom?

I thought about that... as long as its for educational purposes? any attorneys out there? 🙂 (or law students/whatever else)

 

[koolscooby]

Referenced: US Pat. No. 6,624,873

The basic elements of the Dolby AC-3 perceptual coding scheme are set forth in U.S. Pat. No. 5,583,962.

US Pat. No. 6,624,873 [ABOVE] Describes - Matrix-Encoded surround-sound channels in a discrete digital sound format
AND REFERENCES:

US Pat. No. 5,583,962 ( US Pat. No. 5,583,962) Describes - Encoder/decoder for multidimensional sound fields

Well the above is what i just came up with... that is alot of reading... i have an idea though, how about reverse engineering (AKA De-Assembling) the AC3 DLL Codec for windows, or finding an open source one? This would give us some methods and some DSP stuff... it'd be somewhere to start possible 🙄

I may make a website for me to keep track of any developments we make (I would like this to become a real project... if we could comprehend it), i personally though, dont understand most of the mathematics...

Happy new year!!! 🙂

 

[Benjlv]

have you come across this?

http://ac3filter.sourceforge.net/

open source windows AC3 decoder.

 

[Benjlv]

ou ou more

http://www.atsc.org/standards/a_52a.pdf
that looks REAL promissing...although i have little clue what im talking about.
long read though

 

[koolscooby]

yep i've come over them.... alot of reading tho 🙂 your right... time to do some!

 

[elizard]

http://www.cirrus.com/en/pubs/proDatasheet/4923.pdf

could that be it?

I haven't gotten a chance to read through the datasheet yet, i checked the product literature and it does dolby digital/dts decoding, with auto-detect feature ..

 

[soundNERD]

wow, a 56 page datasheet. almost a book on a single chip.


i haven't read the entire thing yet either, but is it a part hobbyists can use?


Also, is the circuit diffucult to make (as in a lot of parts)


-Mike

 

[elizard]

I have absolutely no idea. I didn't get a chance to even skim over the (what can only be described as a) large data sheet.
I was doing some searching for dts decoding, and i ran across a product utilizing that chip, and in the review of the product they stated which chip it uses, etc ... so that's how i got the link

 

[kmt]

The chip type you mentioned is right, BUT:

Nevertheless, You will have to download application code into the chip to do the decompression. And I doubt that application code for windows will work in this chip.

Another problem I see is that you won't get these chips as samples, or even, you can't buy them without having a dolby/DTS/whatever license. I tried it a few months ago and got this answer from Cirrus...

Life isn't simple, ain't it?!?

Greetings from Germany
KMT

 

[Cobra2]

I could not resist the e-bay item...and testing it just now.
First as a 2 channel unit/DAC...I have heard worse...a lot worse!
I'm actually impressed!
Internals shows AKM AK4527 DAC/codec-chip & AK4110 (=?)
and a lot of cheap caps.

Arne K

 

[Benjlv]

AK4527
Internet/Network/General Purpose Multimedia Audio CODEC

2ch 24bit ADC
• Sampling Rate up to 96kHz
• Linear Phase Digital Anti-Alias Filter
• Differential Inputs with single-ended use capability
• S/(N+D): 92dB
• Dynamic Range, S/N: 102dB
• Digital HPF for offset cancellation
• I/F format: MSB justified or I2S
• Overflow flag

6ch 24bit DAC
• Sampling Rate up to 96kHz
• 24bit 8 times Digital Filter
• Single-Ended Outputs
• On-chip Switched-Capacitor Filter
• S/(N+D): 90dB
• Dynamic Range, S/N: 106dB
• I/F format: MSB justified, LSB justified(20bit,24bit) or I2S
• Individual channel digital volume with 256 levels and 0.5dB step
• Soft mute
De-emphasis for 32kHz, 44.1kHz and 48kHz
Zero Detect Function
High Jitter Tolerance
TTL Level Digital I/F
3-wire Serial and I2C Bus µP I/F for mode setting
Power Supply: 4.5 to 5.5V
Power Supply for output buffer: 2.7 to 5.5V
Application: Home Theater System, DVD, Car Audio
AK4527 pin-compatible

too bad it has the DAC inside. I would think that the chip would be fine for movies though.

AK4527
Internet/Network/General Purpose Multimedia Audio CODEC

2ch 24bit ADC
• Sampling Rate up to 96kHz
• Linear Phase Digital Anti-Alias Filter
• Differential Inputs with single-ended use capability
• S/(N+D): 92dB
• Dynamic Range, S/N: 102dB
• Digital HPF for offset cancellation
• I/F format: MSB justified or I2S
• Overflow flag

6ch 24bit DAC
• Sampling Rate up to 96kHz
• 24bit 8 times Digital Filter
• Single-Ended Outputs
• On-chip Switched-Capacitor Filter
• S/(N+D): 90dB
• Dynamic Range, S/N: 106dB
• I/F format: MSB justified, LSB justified(20bit,24bit) or I2S
• Individual channel digital volume with 256 levels and 0.5dB step
• Soft mute
De-emphasis for 32kHz, 44.1kHz and 48kHz
Zero Detect Function
High Jitter Tolerance
TTL Level Digital I/F
3-wire Serial and I2C Bus µP I/F for mode setting
Power Supply: 4.5 to 5.5V
Power Supply for output buffer: 2.7 to 5.5V
Application: Home Theater System, DVD, Car Audio
AK4527 pin-compatible

http://www.asahi-kasei.co.jp/akm/en/product/ak4527/ek4527b.pdf