Software HDCD Decoding? 23
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?"
compatible? (Score:2, Insightful)
when it comes to microsoft, the word compatible doesnt really come to mind
Re:compatible? (Score:2, Funny)
Compatible means that (Score:1)
Suggestion (Score:2, Funny)
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".
Interesting.... (Score:1)
-psyco
Software Only? Sure... (Score:4, Informative)
If you want to write your own talk to Microsoft about licensing it, as they purchased Pacific Microsonics(makers of HDCD) several years ago.
Re:Software Only? Sure... (Score:3, Funny)
Okay, I know this is dumb, but at first I read this as, "the purchased Pacific Histrionics [dict.org], which seems very much like the sort of company Microsoft would want to purchase.
Well, it amused me, anyway.
Good luck! (Score:4, Informative)
It is also patented [uspto.gov].
You can find an overview of how things work during the encoding process here [hdcd.com], 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 [hdcd.com] you can illegitimately use to adorn any illegitimate HDCD products you produce.
Thanks for the heads up! (Score:1)
Re: Technical papers (Score:2, Informative)
Like albums and Dolby noise reduction cassettes, there are complementary filters for encoding or decoding; it's just more complex than an equalization.
Well... (Score:4, Informative)
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.
Re:Well... (Score:1)
I agree with the output part and in addition not that many consumer amplifiers have inputs for 20 bit digital audio either. However, I think that using 20 bit original for Ogg or MP3 should increase the resulting quality because you have more information to select from to discard unneeded pieces during compression. If you had 20 bit output I'd guess that 20 bit Ogg or MP3 (assuming 20 bit format is supported) would sound better than uncompressed sound dithered to 16 bit.
But then, I don't have audio equipment or ears to hear even full 16 bits. Even NICAM [cs.tut.fi] sounds pretty nice to me.
Re:Well... (Score:3, Interesting)
'sides, HDCD essentially only adds 4 bits worth of dynamic range, for a total of 20, which isn't such a stretch for current consumer audio gear. The human ear is likely to be a greater limiting factor than the equipment.
And finally, there will never be any "exclusive content" on the HDCD layer, because there is no HDCD layer. The extra four bits are gleaned from unused space on a CD and interspersed with everything readable by a normal CD player. HDCD is an adjunct to a standard red book audio CD, not a replacement for it. Take away red book compatibility, and you not only remove 16 of HDCD's 20 bits, but eliminate compatibility with existing HDCD players (which are numerous indeed).
You're thinking of Sony's SACD, which can include multiple layers, and currently lacks ripping tools and PC-compatible hardware. I'm sure that Sony would love to convert the world to SACD and then stop adding a red book layer to their music as a cost-saving measure.
I doubt it will ever happen, however. Remember, this is the same company that brought you Beta, Minidisc, and Memory Stick. All of them are good, well-designed products, but lack of interoperability has always held them down, just as it will SACD.
You're right, confused SACD with HDCD (Score:1)
More informaiton is available:
http://www.sonymusic.com/sacd/
http: