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Software HDCD Decoding?
Toshito asks: "I found that I have several CD's with HDCD encoding. I understand that these CD's contain a 20 bits stream encoded in the 16 bits (the original signal is truncated at 15 bits). A standard CD player will play the 15 bits version, but you have to get a HDCD compatible player to access the 20 bits version. My question is: do you know of any way to decode this stream on a computer with software only? Is the decodind method secret and only available in chip (hardware) form?"
this is microsoft technology here .. certainly, it will NEVER be broken!
when it comes to microsoft, the word compatible doesnt really come to mind
I would love to see the Taco, et al. fight a court order kindy requesting them to turn over the userid and ip of the poster who cracked their "encryption system".
Your reality is lies and balderdash and I'm delighted to say that I have no grasp of it whatsoever. - Baron Munchausen
My Toshiba DVD player plays HDCDs.....but this is the first time I've heard that it's a Microsoft technology. Did Microsoft maybe acquire this?
-psyco
Windows Media Player 9 as it comes with Windows XP supports HDCD number of other technologies such as SRS.
If you want to write your own talk to Microsoft about licensing it, as they purchased Pacific Microsonics(makers of HDCD) several years ago.
HDCD, while developed by a high-end audio company whose name currently escapes me, is now 100% owned by (you guessed it!) Microsoft along with the aforementioned original developer.
It is also patented.
You can find an overview of how things work during the encoding process here, but don't expect anyone to tell you how to do any of those things without you first handing them vast fistfulls of cash.
You might be able to glean some useful information from the patent text, but probably the only sane way to go about this effort would be to read the bitstream coming from the CD. And while you should able to discern what the bitstream looks like without too much effort, it would probably be a fairly involved task to learn what it means.
So. My only suggestion would be to give up now before you've wasted any effort on trying. But if you insist on putting real time into this project, here's a couple of nice encapsulated postscript HDCD logos you can illegitimately use to adorn any illegitimate HDCD products you produce.
Kid-proof tablet..
it will play as a regular CD on a normal CD player and thus compatible with it.
Unless you're using some really amazing audio hardware, I wouldn't bother. Most any equipment you'd want to hook up to your PC will not be able to give the full dynamic range of the 16-bit signal, much less the HDCD audio. Most sound cards you use won't be able to either, and that includes ones with SPDIF output. Not to mention, once you encode to Ogg or MP3, all that extra quality goes out the window.
Ripping tools may be desirable when they start putting "exclusive content" on the HDCD layer only, or start making them without the compatibility layer, but there's nothing like that in the pipe, so far as I know.
Now I know exactly what CDs NOT to buy thanks to the logos! I wouldn't want to buy a CD and have some of my money go to Microsoft. Same reason I build all my computers from scratch instead of buying prebuilt with the m$ tax already on it... and yes... I do buy CDs :)
talk to Microsoft about licensing it, as they purchased Pacific Microsonics....
Okay, I know this is dumb, but at first I read this as, "the purchased Pacific Histrionics, which seems very much like the sort of company Microsoft would want to purchase.
Well, it amused me, anyway.
You sound like you know what you are talking about, but you don't. And you are just plain wrong to boot!
That's nonsense. I have an outboard DAC with HDCD decoding. I feed it a standard SP-DIF stream from my CD transport, and the DAC automatically recognizes the information encoded in the LSBs, and decodes it.
It has ABSOLUTELY NOTHING to do with any physical properties of the disc. Whoever told you that was lying.
As for encoding 20 bits into 16 bits, you obviously can't do that losslessly, without some form of compression that would make the disc unlistenable on standard players. What they somehow do is encode some information in the LSBs of the signal, that has the capability of extending the dynamic range to 20-bit, in some circumstances. If you want to know more about it, you should try to search for the papers presented at the AES (Audio Engineering Society) conference, and the like.
Unlike AC3, at least HDCD isn't part of a broader standard, such as DVD.
Two layer SACDs are what I was thinking of, and I confused them with HDCDs.
/ /www.hdcd.com/about/index.html
More informaiton is available:
http://www.sonymusic.com/sacd/
http:
-- Crutcher --
#include <disclaimer.h>
Like albums and Dolby noise reduction cassettes, there are complementary filters for encoding or decoding; it's just more complex than an equalization.
buy a new dvd player (many new one are including hdcd support right out of the box). hook up the optical output (or whatever the highest quality ins'n'outs you have, however they might not be good enough...) to your fancy soundcards input. start recording. don't bother to encode to mp3 or ogg if you are truly concerned (ie if you are a diehard audiophile) with hifi sound as any lossy compression will degrade the quality.
Large print giveth, and the small print taketh away