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SACD-CD Hybrids -- A Way Out For Us Both?
"An interesting feature of the SACD layer is plenty of room for strong digital rights management code.
Here's my proposal: it should should allow artists to get paid, and the citizens to have archived and portable copies of the recording they have purchased. The record companies should produce a superior audio product and get to protect it from serial copying. The CD layer should be freely available for personal copying such as to a computer or portable digital player. These 2 basic concepts are a model that can be applied in the future, when better formats become available. It may also serve as a model for digital visual recordings. Perhaps we can get the artists, publishing companies, electronics manufacturers and the federal trade commision to all agree on this compromise: 1.The high quality recording allows only one copy of itself to be made for archival purposes. 2.The lower quality recordings are available for personal copying.
Personal digital technology has brought a tremendous change to the realtionship between media publishers & consumers. It's time for a new paridigm that will re-define that relationship for modern times."
The SACD standard, published by Philips and Sony in March 1999, defines three possible disc types (shown above). The first two types are discs containing only DSD data; the single layer disc can contain 4.7 GB of data, while the dual layer disc contains slightly less than 9 GB. The third version - the SACD Hybrid - cleverly combines a single 4.7 GB layer with a conventional CD that can be played back on over 700 million cd player world wide. This concept is the essential link between the new SACD format and the well-established CD.
From the outside, the SACD Hybrid Disc looks like any other 12 cm diameter and 1.2 mm thick optical disc. A closer look reveals that the disc is a bonded combination of two 0.6 mm data carriers: one containing the SACD data, the other the CD data. The reflective coating on the SACD carrier has the optical characteristic to be reflective for the light used in the SACD pick-up (650 nm), but to be transparent for the light used in a CD pick-up (780 nm). To a CD pick-up, the SACD layer is virtually invisible, as a result, the CD layer contained within the SACD Hybrid Disc is fully compatible with the "Red Book" CD standard, and can, therefore, be played on all "Red Book" compliant players.
Well, if the diagram is correct (i.e. the data is cheesecloth encoded, and the protection lies in the fact that the encoding layer is semi-reflective, the only thing you'de need to do to build an evil, satan-worshipping CIRCUMVENTION DEVICE would be to mark or "paint" the CD on the reverse side so that it can be sensed in a reader, and read the disc in two passes. Something like a a clean mylar sheet shaped like a flat donut, used for each side. Once youve got the data, simply a matter of doing the math, and whammo, youve got both the "new" high-resolution side and the "old" normal audio side. Looks like we'll have a "frying pan" for our burners soon.
Don't they think about this crap beforehand?
Bowie J. Poag
They can be manufactured using current methods. Redbook on one side, SACD on the other. No need for fancy layers.
Just as an FYI, a CD's sampling rate is 44.1Khz (44,100 samples per second), SACD by comparison is 1.2Mhz (1,200,000 samples per second)
Except, audio-wise, it won't make a damn bit of difference unless you have super-human hearing.
What good is SACD with 20 to 20000 Hz speakers, or even 20 to 32000 Hz speakers?
You could only do that if you're willing to bend some of the rules WRT the construction of a CD. The CDDA layer is on one side of the disc, while the SACD layer would be placed somewhere in the middle. If you tried making a "flippy" disc with both CDDA and SACD layers in the middle, either (1) the disc would be too thick to be handled by some CD players (1.2+x mm) or (2) some CD players might be unable to focus on the CDDA layer since it would be too close to the pickup. ("Flippy" discs work for DVD because that standard was developed with double-sided discs in mind...the data layer(s) in a DVD is/are in the middle.)
20 January 2017: the End of an Error.
The great truth of recorded music is: The life and death of any format is in the software, not the players, not the technology, not the marketing. How much music is there? The biggest problem SACD has is that there's less than, oh about 400 discs available, mostly classical and jazz, and mostly older recordings, at that. One great advantage for SACD is that Sony has begun all mastering in DSD, the one-bit technology behind SACD. That recently-released CD you bought from a Sony label was probably recorded using DSD and downsampled for the CD master.
MP3 and other compressed formats have lots of software available.
One other note: I have a two channel system (i.e., Stereo) but SACD supports a 5.1 channel layer, too. So a fully-loaded hybrid SACD has a 2-channel Red book CD layer, a 2 channel SACD layer, and a 5.1 channel SACD layer. Only the 2 channel SACD is required.Found: r3mix.net
"Please - have at it, I haven't heard any proposals yet that hold water..."
If there were a magic 'instant return on investment' business plan, the Record Industry wouldn't have waited until MP3s got popular to switch to it.
They could make just about any business model profitably if they'd try it. There are two reasons they aren't, though:
1.) They assume that the consumer will not pay for anything. We are all thieves, therefore they cannot provide anything 'free'.
2.) They'll have to price themselves fairly, vs. screwing the consumer at every turn.
The RIAA is in a unique position because it's settled nicely into a virtual monopoly without getting much attention from the government. Mp3s are causing them to have to behave competitively, but they dun wanna cos they dun wanna lose their margins.
Pity. I expect that what'll happen is a new, internet friendly organization will come along and dethrone the RIAA. They may not make such ridiculous profits, but I imagine they'll easily make a comfortable living as long as they come up with a business model that considers our needs.
"$2 per MP3, or $7 for the whole album"
"Derp de derp."
For those, like me, interested in the encoding/decoding technology used in the DSD (digital stream data) that the SACD is encoded with here is a short, useful paper on 1-bit Sigma-Delta Modulation . Those remotely familiar with digital signal processing shouldn't have any difficulty with it, but it isn't an introductory piece or tutorial either.
-Adam
The SACD uses a different sampling technique from a CD. Both of them stare with a sigma delta modulator, which breaks the analog signal from the mic into a series of pulses, the denser the pulses the higher the amplitude. A normal recording counts the pulses over about 45 microseconds (for 44.1 kHz) to get a 16-or 24-bit wide number IIRC. when the music is played back, it is converted back to 1-bit by, say, varying the duty cycle of a pulse-width modulator.
The SACD just records the pulses from the SD modulator to disc, which is responsible for the huge number of samples.
So instead of being 44.1 kHz*16 or 24 bits per sample, it is 1.2 MHz at one bit per sample. Therefore, it looks *less* like an analog wave than a CD recording. Essentially, Sony regards counting the pulses as a very effective but slightly lossy compression method that they wish to eschew. BTW I can barely tell the difference. Even a good MP3 is good enough for me.
I hereby place the above post in the public domain.
A regular old cd already produces more sound than the human ear can detect...
This claim is absolutely false.
Go into any recording studio, record an analog source (acoustic guitar or a grand piano, for example) at 16bit/44.1KHz, then at a much higher resolution (say, 24bit/96KHz). Then play those back through a studio monitor sound system.
You can ABSOLUTELY hear the difference. Well, maybe you can't, but some people can.
I can tell the difference just recording vinyl through a DJ Mixer into my sound card... The quality difference between 16/44.1 and 24/96 is really staggering, especially in the very high and very low end... Of course, I can't burn a CD at that quality, and dithering the sound back down to 16/44.1 makes the sound worse than just recording it at 16/44.1 in the first place.
But the point is, there IS a difference, and it's noticeable.
Anyone can polish a turd... and SACD is a turd polisher.
I'm not sure what you mean by "above 44Khz". The absolute limit of CD audio is 22KHz as shown by the sampling theorem that basically states that the sampling rate must be a minimum of twice the maximum frequency sampled. Besides, the goal of high fidelity audio is the faithful reproduction of the original sound. In the frequency domain, that translates into flat response between 20Hz and 20KHz with a smooth rolloff above and below. CD audio does not do that.
A huge problem that plagues CD audio (from the audiophile point of view) is the "brick wall" filter that is employed at 20KHz. This low pass filter is so sharp that it can cause some pretty nasty artifacts if it's implemented improperly (for which you should read "cheaply").
Your point about "mixers, microphones, and other equipment" would be well taken except that Sony's Direct Stream Digital (DSD) recording system doesn't allow for post-recording mixing at all. So, what you record is what you get. Obviously, then, the quality of the recording stream should be correspondingly high. I think that you'd be quite surprised at just how high the standards for DSD recording equipment are.
A significant advantage of SACD over CD is that because of the 1 bit sampling and the dithering that follows, quantization noise is moved way up in the spectrum, well beyond the range of audibility. Further, the noise floor of SACD is substantially lower than that of 16 bit CD. The frustrating part of CD audio is that although it should provide a theoretical 16 bit dynamic range, due to quantization and other digital artifacts, even the best players are limited to perhaps 12 or 13 bits. Sure, you might dismiss that as a mere detail, but it is quite audible.
I've got a Sony SACD player. I've also got a nice Rega turntable and a Musical Fidelity CD player. A well cared for LP certainly outperforms a CD and is on a par with the SACD player. Obviously it's difficult to keep an LP in excellent condition over time, which is why I have a very large CD collection. But, quite frankly, the 30 or so SACDs that I have most definitely sound better than the CDs that they replaced...and I'm no golden-eared audiophile.
I'll certainly agree that my speakers won't reproduce anything above 30KHz, but that's not the point of SACD. The point is that the dynamic range is substantially greater and the digital artifacts that are the domain of multibit sampling (and relatively low sampling rates) are essentially eliminated. Frequency response is not the issue here.
I suppose that the case of SACD being a "turd polisher" could be made if you wanted to stick one in your average boom box and claim superior sound. But then again, I guess you could say that in that regard, CD is just a turd polisher compared to cassettes.
-h-
The SACD specs were originally written with regular CD tracks in mind. So both have been there from the beginning.
"A plan fiendishly clever in its intricacies"- Homer Simpson
That isn't acceptable. Fair use rights exist for ANY copy of a work which you can otherwise legally access. Not just some.
For example, the RIAA cannot claim that ripping CDs for mp3s is illegal b/c ripping audio tapes is possible, or even endorsed. Likewise, the MPAA cannot claim -- though they have -- that VHS copying is a substitute for DVD copying.
If a work is published, it's subject to unauthorized copying, and that's that. Not all copying is legal or illegal, but it depends on the circumstances and should not be prevented unless it is absolutely certain that legal copying, which includes copying anything once the work falls out of term, even if the source is a copy produced during term, is not impaired.
-- This and all my posts are in the public domain. I am a lawyer. I am not your lawyer, and this is not legal advice.