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DVD-A = ? SACD = ?

post #1 of 29
Thread Starter 
What's the difference between the 2? Is DVD-A 'higher resolution'? Does that mean it has higher quality? Or is it the other way around? What are their bitrates, sampling rates, etc.?
post #2 of 29
This should probably be in the Other Technologies forum, since it's not a question about SACD or DVD-A sources in particular.
post #3 of 29
Neither are higher resolution than the other (or so is still argued), but they are both higher resolution than regular Redbook CD. DVD-A is higher bit-rate PCM (same technology as CD) -- up to 24/192. SACD is DSD, a (relatively) brand new technology.
post #4 of 29
DSD uses 1 bit words, but samples at about 2.3 MHz
post #5 of 29
Thread Starter 
>>2.3MHz

Say WHAT???
post #6 of 29
SACD: 2.300.000 1-bit samples per second.

DVD-A: 192.000 24-bit samples per second.


but SACD is based on newer (and probably better) technology.
post #7 of 29
Actually the DSD technology behind SACD is not new. At the time of CD's public relese back in 1983, the DBX company (yes, the noise reduction people) had a digital recorder/player using almost identical technology as Sony does now. It was called the DBX 700 and it sampled a single bit at 700kHz, and used U-matic Pro broadcast machines as the storage medium. Those who were around in '83 may recall the total blitz that Sony/Philips had in the media regarding CD's "Perfect Sound Forever". DBX acting alone could not compete and were swamped, even though it was a better technology, even at it's early stages of development.

Sony also pushed very hard for recording studios to adopt digital techno;ogy, and I beleive, offerred products at prices where they could not have been making money, so they would adopt. If studios had stayed analogue, it would have made a mockery of all the hype about digital's benefits.

I find it very ironic that now, the same technology that was overrun in the early days of digital, is now touted by the company that pushed it out of the market, as the next step improvement in digital technology.

If I may correct Joe on a small point, SACD samples at 2.822 Mhz, not 2.3 MHz.

The simplest explanation of how it works is thus:

PCM (using Redbook as an example) - takes samples 44100 times a second. Each sample is given a value that is proportional to the waveform at that instant, one of 65536 possible values. These values are stored, manipulated etc and then sent to the DAC to recontructed into analogue so we can understand it. DVD and DVD-A are exactly the same technology, just using more and smaller steps to sample (24 bits vs 16 bits) and higher sampling rates (up to 192kHz vs 44.1kHz). Very, very few ADCs /DACs approach true 24 bit performance, even very expensive Pro units like dCS.

DSD - 2.822 million times per second, thie input waveform is sampled, and compared to the sample before. Is it bigger (+1) or smaller (-1) than the previous sample, and then that 'bit' becomes the next bit of data in the stream. When converted back into analogue, each up or down bit increases or decreases the output voltage from the DAC by a tiny amount. The bitstream for silence would be, +1, -1, +1, -1, +1, -1 etc. In many ways DSD is easier to implement.

This is a very simplified explanation of how they work. A Google search on SACD or DSD (Direct Stream Digital) should turn up a few hits and lots of interesting reading. Some good tech papers can be found at http://www.dcsltd.co.uk/papers.htm especially the on titled "Effects in High Sample Rate Audio Material".

As for which is the best sounding or will win in the marketplace, I vote for vinyl.

Sorry for running off at the mouth here, but I hope this explains it a bit. If you want further info or a better explanation, I'd be happy to help.

Cheers
Brett
post #8 of 29
Very interesting, Brett. I've been looking for a brief synopsis of PCM vs DSD. (I also agree with your remark about vinyl!)

post #9 of 29
Quote:
Originally posted by arktraveller
Very, very few ADCs /DACs approach true 24 bit performance, even very expensive Pro units like dCS.
I find it interesting that you do not quote the corresponding datum about DSD...hmmm...(strokes chin)...

No seriously, otherwise, very good synopsis!
post #10 of 29

DSD bullshit and why SACD won't win...

...there's a funny thing about DSD that, while perhaps negligible, is better handled with PCM:

Say you want to represent as perfect a square wave as possible. There is absolutely no way to represent that wave perfectly using DSD. The one-bit system could "steer" the wave up to it's plateau peak rather rapidly, but it still stands that the exclusively-upward "steering" forms what amounts to a quick, positive slope, rather than a flat "wall." With PCM, exactly representing this "wall" is easy: just jump from those low, sub-zero value right to a positive high value and voila, there you go, a perfectly-represented square wave.

I think that even though DVD-A effectively has a far lower Nyquist (highest digitally representable frequency for a given sampling rate)...considering DSD technology can theoretically represent a 1.4112 MHz (!) wave (since it has it's 2.8224MHz sampling rate)...DVD-A *still* reaches far above the range of human hearing (a possible 48kHz tone at the standard 92kHz sampling rate, for example).

That is still amazing and I think the DVD-Audio format will push DSD into being the ultimate archive format and nothing more. I don't believe it will survive in the consumer market.

Then again, if Sony offers SACD titles for current CD prices and DVD-A's stay "up there" a la Laserdiscs, SACD might gain ground. Also, if there is a proliferation of the Apex Digital AD-7701-style dual-mode players, that might help.

Best,
Matt
post #11 of 29

Re: DSD bullshit and why SACD won't win...

In a word, transients. Yeah, I used to argue that, too. But it's all theoretical, and anyone who's ever heard them both say that SACD doesn't have a problem with transients. (shrugs, "I dunno"?!?)

But then that stupid watermarking...they need to ditch that and quickly, otherwise they are going to lose.

I just read another review that said the worst Sony SACD player (670) is better than the best DVD-A player. Statements like that are going to kill DVD-A. Surround sound is a novelty, and now that SACD has it too, they got nothing. Nuh-thin'.
post #12 of 29

'Scuse my ignorance...

...but is it DVD-A or SACD that has "that watermarking" scheme? I agree: if it persists, people probably won't want it. Then again, many consumers seem to be jumping onto the Windows XP boat, so who knows.

It's unfortunate that there are so few of us audiophiles out there. Clearly we're at the point where if there is lack of broad interest in higher-resolution format, neither DVD-A or SACD will forge forth in any meaningful measure. This especially holds true in the crucial "titles" side of things.

I think that people have either been through a format war or are acutely aware of it's implications (i.e. the format you've invested in is now being phased out) and I believe that the only way we are going to get either of these formats widely accepted is if more dual-mode players are released, such as the aforementioned Apex AD-7701. These players must have some measure of sonic and build quality (considering that the "sell" to Joe Consumer would be better sound quality) and since they will play both formats, they are future-proof. For me, if there weren't so many bug reports with the AD-7701, I would buy it in a second (I've seen it for as low as $269).

IMHO, this is what were faced with and I think Sony's "diva" tactic of only releasing non-DVD-A capable SACD players and current- and back-catalog titles is going to hurt it. People are no doubt interested, but will remain ultra-wary of the whole deal until they feel it's "settled." A shortcut to "settlement" is dual-format players.

Anyhow, I've said my bit...

Best regards,
Matt
post #13 of 29
Who carries those Apex AD 7701's? I could get interested. Otherwise , I too will wait.

"As for which is the best sounding or will win in the marketplace, I vote for vinyl. "

Me too.
post #14 of 29

Re: 'Scuse my ignorance...

Quote:
Originally posted by Matt
...but is it DVD-A or SACD that has "that watermarking" scheme?
Only DVD-A has audible watermarking. SACD explicitly does not (unless the watermarking was imprinted before the final mastering process). SACD has a copy protection scheme at the digital level (encryption), but it's not audible.
post #15 of 29
SACD doesn't have watermarking, but there is no way to output the info digitally... yet. For the record, SACDs are really ridiculously better than DVD-As. It's impossible to do the test really scientifically since no high end players can play both, but I have never heard a DVD-A sound as good as an SACD on my "low-end" C333ES.
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