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how to tell bit resolution of redbook CDs (16, 20, 24 bit)?


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14 replies to this topic

#1 of 15 OFFLINE   Jason8

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Posted December 16 2003 - 05:07 PM

Is there a way to tell the bit depth resolution of a regular audio CD? I know if it is higher than 16-bit, it will say on the packaging that it is 20-bit or 24-bit. But I have some remastered CDs that don't indicate bit resolution. If it doesn't say, then does that mean 16-bit? Perhaps is there some software utility that can say what it is? Thanks.

#2 of 15 OFFLINE   Kevin C Brown

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Posted December 16 2003 - 06:34 PM

CDs are always 16 bit/44.1 kHz. They might have been dithered down from 20 or 24 bit during mastering (if I'm saying that right), but 16/44.1 is all you get. You'd only know that if it was in the liner notes somewhere. Maybe someone can comment about XRCDs, HDCDs, etc, too.

The funny thing is: if you read the measurements section of even the best DVD-A and SACD players reviewed in S&V, you *still* only get 18 to 20 bit resolution.
If it's not worth waiting until the last minute to do, then it's not worth doing.

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#3 of 15 OFFLINE   ChrisPATT

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Posted December 17 2003 - 03:46 AM

Then why do some of my CDs read 24 bit on the cover?

#4 of 15 OFFLINE   Brian L

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Posted December 17 2003 - 03:58 AM

Marketing of the fact that they were mastered using a certain process, I would wager.

As Kevin said, a Redbook CD is 16/44.1, end of story.

BGL

#5 of 15 OFFLINE   Jason8

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Posted December 17 2003 - 04:00 PM

Thanks for the insight!

So if all redbook cds are 16-bit/44khz, then why do the advertise some players being 24-bit/192khz? Is it just another marketing ploy, since not even high-rez audio cds can achieve that?

#6 of 15 OFFLINE   Brian Perry

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Posted December 17 2003 - 04:26 PM

Quote:
So if all redbook cds are 16-bit/44khz, then why do the advertise some players being 24-bit/192khz?

Those claims are for DVD-audio players, which can also play redbook CDs.

#7 of 15 OFFLINE   Kevin C Brown

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Posted December 17 2003 - 05:24 PM

And... there are some advantages to using 24/192 DACs to decode 16/44 CDs rather than 16/44 DACs. Something to do with the steepness of the anti-aliasing filters used, among other things.
If it's not worth waiting until the last minute to do, then it's not worth doing.

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#8 of 15 OFFLINE   Jason8

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Posted December 17 2003 - 05:31 PM

interesting...actually I have a DVD player that says it has 24bit/192khz DACs but it is not a DVD-Audio player, but I guess what Brian said about "anti-aliasing" filters or whatnot :b

this is abit off-color, but when using Digital Optical or Digital Coaxial connection from DVD player to HT Receiver, can different DVD players sound better? I have heard some people comment that "oh, the audio from this DVD player has more warmth and detail" or something to that effect. But using a Digital optical/coaxial connection, you're just sending bits to your Receiver's DACs, so it's just your Receiver's DACs processing the info, correct? Or is there some "voodoo" involved?

#9 of 15 OFFLINE   Brian L

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Posted December 18 2003 - 02:17 AM

Actually, it was my esteemed colleague Mr. Brown that commented on the filters...

As for one player used as a transport sounding better than another, thats a subject of great debate. I personally think digital is digital in terms of moving the data from one place to another. Any sonic differences would be due to DACs, and any circuitry that is downstream of those.

Of course, if you cruise over to Audio Asylum, you will probably find posts that say player "A" blows player "B" out of the water when used as a transport.

These folks also think A/C wall outlets can impact the sound too.

BGL

#10 of 15 OFFLINE   Joel Fontenot

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Posted December 18 2003 - 06:13 AM

Quote:
interesting...actually I have a DVD player that says it has 24bit/192khz DACs but it is not a DVD-Audio player

No, but that player can read regular DVD's with PCM audio that may be encoded up to that rate, if I'm not mistaken. And that should include the few DADs (Digital Audio Discs - a DVD-player compatible disc with audio only and, maybe, limited video for titles and such) that were made before DVD-A became the (sort of) big thing.

BTW, CD's that were mastered at 20 or 24-bit means nothing to me. Mastering engineer Steve Hoffman masters straight to the bit-depth that the playback medium he masters to will play at. When he masters to SACD, he'll use the proper DSD encoders from the analog source - doing whatever eq'ing he needs while still in the analog chain. When he does redbook, he'll remaster again from the analog source and go straight to the 16-bit encoders (unlike some who will just run a PCM conversion from the DSD or other high bit-depth master). That way the 16-bit version is the closest to the original signal. It's not dithered (or re-quantitized) from another bit-depth that may not evenly divide into 16 and instead end up with rounding errors that may give you a value at a particular sample point that could be different than what the straight 16-bit encoder might give you at that same particular point.

I have a few 20 and 24-bit mastered material on redbook CD that I find is no better than an earlier original CD that was all 16-bit (other than just being louder and distorted because of the dynamic range sqwishing). But there are a few cases where the material used in mastering might have been better and did result in a better remastering effort on the final CD - but that was before the current loudness wars.

Joel
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#11 of 15 OFFLINE   LanceJ

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Posted December 18 2003 - 08:25 AM

From reading many posts on pro forums, most professionals very much believe in mastering in bit depths greater than 16 because it gives them an electrical "cushion" while doing whatever processing is needed. So if any computing mistakes occur, they will usually be confined to those last few bits. And when transferring to the CD standard of 44.1kHz/16bit, those mistakes will be left behind. Obviously, if you use analog processing methods then this doesn't apply (but analog can introduce it's own set of distortions so there is no free lunch here).

As far as converting to 16 bits from say, 24 bits, all that is needed is to literally ignore those 8 extra bits--that's it. There isn't any true conversion process going on. What you are losing is the finer voltage steps that larger bit words provide, (which many recording people say is more important than the sampling rate as far as sound quality goes, at least on the high $$$ convertors they use in the studio):

A 24 bit word gives the digital encoders/decoders 16,777,216 individual voltage steps to "choose" from to build the music waveform (a binary word has two possible values--1 or 0--in each place, so: 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 = 16,777,216).

A 16 bit word only provides 65,536 individual voltage steps.

And yes, many convertors aren't built well enough to squeeze out those extremely fine voltage steps found in the last few bits of a 24bit word. But I THINK I read somewhere that the average human can't hear better than 18bit resolution, so this may be a nearly moot point, (though the concept of processing using 24 bits is still valid).

Now, converting from 96kHz or 48kHz down to that oddball 44.1kHz rate is where you can get into trouble--this is where high quality equipment is required for the best possible sound.

LJ

#12 of 15 OFFLINE   Joel Fontenot

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Posted December 18 2003 - 12:35 PM

It's true that if you're going to be processing the sound in the digital realm, do it at a high bit-depth. I'll do that when I do my own needledrops of my LP's - I convert to 32-bit, process as I like, then re-convert back to 16 to make a CD-R of it.

It's what the professionals do to the real masters in the digital realm that I don't like. I'd rather that they didn't digitally process at all. I know that analog processing adds it's own distortion, but it's a much more "agreeable" distortion that is much easier on the ears when done right.

Joel
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#13 of 15 OFFLINE   Scott Strang

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Posted December 19 2003 - 07:56 AM

[quote}..do it at a high bit-depth. I'll do that when I do my own needledrops of my LP's. [/quote]

Howdy Joel

Are you using a soundcard with digital in and an outboard a/d? If so what a/d are you using? I've been wanting to transfer some reels and LP's to some hi-res format for storage probably in WAV format. I'd like to do them at at least 96khz/24bit.

#14 of 15 OFFLINE   Ken_McAlinden

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Posted December 19 2003 - 08:26 AM

Quote:
From reading many posts on pro forums, most professionals very much believe in mastering in bit depths greater than 16 because it gives them an electrical "cushion" while doing whatever processing is needed.

...or, in far too many instances, not needed. Posted Image

Regards,
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#15 of 15 OFFLINE   Joel Fontenot

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Posted December 19 2003 - 05:11 PM

Quote:
Are you using a soundcard with digital in and an outboard a/d? If so what a/d are you using? I've been wanting to transfer some reels and LP's to some hi-res format for storage probably in WAV format. I'd like to do them at at least 96khz/24bit.


Scott, I wish Posted Image

No, I'm just recording from a my phono-stage equipped receiver tape line-out straight to line-in on my Soundblaster Live at it's max of 16bit. After that, I convert to 32 to do my clean-up, processing, volume changes, whatever. At least this particular card was one of the few SB cards of that time that could record easily above 20kHz. Most of the others topped out at about 18k regardless of sampling rate (which I can push to 48kHz).

As a minor upgrade, I plan to get the Turtle Beach Santa Cruz card, regarded as a good analog recording card. It records at a max of 18-bit, 48kHz, but it's other specs are quite good. And although not dead-silent, it's quieter than the SB cards as far as generating it's own noise when recording. Plus, it doesn't digitally re-process after A/D conversion while recording like all SB cards do.

The M-Audio Revolution card would be better for straight high-res recording without an outboard. It can do 24b/96k. Maybe for my next computer.

Joel
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