The 24-bit challenge

[windowman]

The advantages to 24bit and the increase in SNR is pretty obvious to anyone who uses 24bit.

Even an SB Live has a signal to noise ratio of around 93db at 16/48. Man I'm sorry but the difference between 93 and 100 in the SNR department is so infinitesimal as to be nothing. I mean sure you could hear that tiny bit of hiss if you really crank the volume but good grief man! How gay would a dude have to be to get that persnickety over anything in life? It's just incredible to me that something like that would be an issue with anyone. I remember that not long ago we used to think that if you owned a Studer or Otari machine and you ran your tape at 30-ips that you'd get a SNR of over 70-db and you didn't have to use noise reduction because that was perfectly acceptable. And you're crying like damn girl over 93?!! I mean this is what bugs me the most about the people who would actually cry over having to use a 16 bit card. First, I don't believe a darn one of them could possibly hear the difference. Second, it's just so freaking GAY! I mean be a man for Pete's sake. Who the hell cares? I'd be perfectly happy recording on a Fostex B16 with a SNR of 72 and and a frequency response of 40 to 18k. A lot of great records were made on those little machines. They sound perfectly fine. An SB Live or any other 16 bit card will sound even better but I don't give a damn. I mean how freaking lame do you have to be to cry over something like that? It's like refusing to go outside because it's 68 degrees and not a perfect 70. I mean, I expect Richard Simmons to act that pampered but frankly I wouldn't buy his album if he made one. Somebody like that wouldn't have enough charcater in him to make worthwhile music. He'd be in the MP3 clinic saying, "Listen to my latest remix man! Ain't it cool?" Yeah, that's what I want to hear, your damn remix....

Ethan, I appreciate what you're trying to do but believe me, a sissy will always find an excuse to be a sissy. No matter what you bring out to the testing floor they'll cry "unfair" to. It'll always be one lame excuse after another. I once put several people to the test with sound files like that. I made a small 16/44.1 wave file and then copied it, then dropped the copy to a 128k MP3, then back to a 16/44.1 wave, then dithered to a 16/48, then back to a 128k MP3 copy again. Then back to a 16/48 wave. Then dithered again to 16/44.1 That's a hell of a lot of signal degradtion that these golden-eared people should have been able to hear according to them. Most people guessed the wrong file was the original. They actually thought the file that I put through all the changes/resaves was the better sounding file! But do you think they'd admit their shortcomings in the hearing department? Not on your life. It was one childish excuse after another. This test was flawed for this reason or that. Right....

Do yourself a favor, get off the internet and go to the gym and hang out with some men. And watch out for the guys who bring a towel to wipe down the equipment before they'll touch it. This is sickening!

As to the listening challenge I'd give em this order of best to worst:

file 1 best
file 5 second best
file 2 third best
file 3 fourth best
file 4 worst

To be honest though 2, 3 and 4 sounded identical to me. 1 and 5 were pretty much identical too except they had a bit more treble than the others.

 

[mcr]

wow ...

finally a couple of recordings in 24bit and 16bit ... now, I can't fucking believe the big fuss everybody's been making about the huge quality difference. The difference is a big, fat 1MBit JOKE.

I got three right and two wrong ... which is best explained by luck. Statistically, significance is usually set at 5% or 10% levels ... hence, in order to show that your decisisons are more than mere guesses you should be able to have all FIVE right. Getting four right out of a sample of five is not enough and would not be considered as proof by any scientist.

I'm sure there're some people who are gifted with exceptional ears. However, I dare to suggest that most people who ramble on about 24bit's superior quality in comparison to 16bit are probably just babbling ...

MAYBE, the quality difference is more audible after recording several audio tracks (e.g. 12). That'd be a something I'd like to have put before me. I guess that's what many 24bit defenders would say ... and they might be right. What do I know. But as far as my ears are concerned (and I grew those myself): 24bit = 16bit ... if you hear a difference, then you're really great, deserve a medal and I'll call you my hero ...

 

[Lt. Bob]

Hey guys, if you put these sounds to Mp3 and put them on the net to listen, then they have no relevence to how they would sound in the original format because Mp3 is such an inferior format. The differences between formats and bit rates can be pretty subtle which is why some people either can't hear them or don't care about them. So if we're talking subtle differences--it seems to me that Mp3's could make them inaudible because of Mp3's lower resolution.

 

[windowman]

Hey guys, if you put these sounds to Mp3 and put them on the net to listen, then they have no relevence to how they would sound in the original format because Mp3 is such an inferior format.

Hee, hee! I just knneeewwwwww somebody was going to say that!

 

[Lt. Bob]

Well-- why not? As I said when I edited my post--if the differences are subtle, then putting them in a format that has lesser resolution could certainly mask subtle differences. I'm not saying the differences are night and day. But for those who record say...mostly delicate acoustic stuff; even a subtle difference might matter.

 

[windowman]

But they're not mp3's, they're wave files.

 

[Lt. Bob]

OK so they're the same as a cd ? I guess that's a dumb question to you but since I do all my recording with stand-alone recorders and analog board--I'm not hip to all the 'puter stuff. Are wave files what are on say a standard cd? If so then of course I'm totally wrong about the differences being masked. But I do hear differences between 16 and 24 bit A/D&D/A converters. Is this a different process than 16 or 24 bit recording? I mean I understand that the converters and the recording are seperate issues. But if I can hear differences in the converters--why wouldn't there be differences in the recording process also? I wanna understand this.

 

[Teacher]

the biggest variable/problem wit this test are peoples playback system...are their playback systems good enuff to even play the file how it actually sounds are will it color the sound and make it sound good anyway as MOST commercial even cheap studio amps and speakers do...as for just volume changes i doubt my ears are good enuff to tell and my experience wit sound is very limited...i always understood 24 bit as being the savior for using those plug-ins and maybe that bias makes me THINK i hear a difference in the hi mid and high range who knows,..

i think a better test would be drums wita drum machine so u can record in 24 bit and 16 bit w/o any diff in how its played or sounds, cuz i listened and yea normal people def can't tell the diff...shit i wouldn't been able to tell if i wasn't really really trying to listen...and i'm prolly wrong anyway

u mind if i post this thread at other BBS?

 

[camn]

Hold on, man...you arent making any sense.. which doesnt help people like me who dont have the best grasp on this stuff to begin with.

camn,

Actually, this is quite scientific. According to a lot of people, the whole point of 24-bit recording in a 16-bit CD world is that after dithering, the result is better than just using 16 bits in the first place.

I beg to differ, sir, with this 'lot of people'. The difference is when you process the hell out of a .wav.. THEN dither. minimal processing = minimal rounding = minimal difference. when the ONLY process you do is dithering... its hard to tell the difference. But who here does ZERO processing??

> If I drop volume be 18db ... Im filling those last 3 bits with ZEROs. Which is MUCH different then chopping the bits. <

No, it's exactly the same. Since audio programs won't play a 13-bit file, the only recourse is to leave the file at 16 bits but zero out the lower bits. Which is just what I did.

> because when I bring the volume back up... the sample can use those bits again!! they are STILL THERE!!! <

Yes, they are still there, but they're all zeros! To take this to the extreme: Suppose I drop the volume by whatever it takes so only one bit is active, and then raise it back up. What do you think it will sound like? Do you see the point now?

--Ethan

lets get a little technical.

suppose we have the 24-bit word....
1111101001010100110101111
for instance.

if I truncate or dither it to 4 bits.. i may get a number like this:
1111
you see. You'll notice I have some 120db LESS dynamic range. If i tried to push it UP at all... Id clip.


NOW ON THE OTHER HAND!!
suppose we have the 24-bit word....
1111101001010100110101111
again..

If I lower the volume to
000000000000000000001111
(which will sound very similar to 1111)

Youll notice I still have 120db of headroom. I can increase the volume without clipping.

do you see the point? Im not trying to be nasty... but get real man. A really QUIET 24-bit sample is NOT THE SAME as a 4-bit sample.... regardless of what you THINK is "active". placeholders (aka zeroes) are just as active as anything else....ask anyone whos waiter accidentally charged him $200 instead of $20. Just because the "2" is the only active digit..??>..?>?@#$@#%??

try and make sense here.

xoxo
oh, and Teacher.. this thread is filled with confusion and misinformation!! why repost it?

xo

 

[mcr]

Are wave files what are on say a standard cd?

I'm no Compsci either but in order to burn my songs on CD, I have to save them as .wav files .... I assume they will not be modified during the burning process, so essentially, the songs on a cd should be in .wav format also...
Anyone here who could shine expert light onto this?

But I do hear differences between 16 and 24 bit A/D&D/A converters. Is this a different process than 16 or 24 bit recording? I mean I understand that the converters and the recording are seperate issues. But if I can hear differences in the converters--why wouldn't there be differences in the recording process also?

The difference you hear might be found in their converter quality, not in their conversion rate.

 

[Teacher]

i don't really care too much for the thread i just wanna see if other guys can hear the difference between them

 

[Lt. Bob]

OK so what I need to do is burn the samples to cd, then play it on my reference system so I have a system that will reveal small differences. My 'puter system certainly won't do. So when I get home from work today..that's what I will do. Let you all know what I find out. MCR has a point. Since cd players do sound different, even with the same bit rate converters, maybe what I heard was just different quality converters. So let the testing begin.

 

[Ethan Winer]

camn,

> The difference is when you process the hell out of a .wav.. <

Yes, that too. But all the time I hear how important dither is to maintain clarity, depth, imaging, whatever. So if nothing else, my files test whether 24 bits is better per se - as in a direct to 2-track recording - and also whether dither is in fact useful for normal material recorded at normal levels.

> NOW ON THE OTHER HAND!!
> suppose we have the 24-bit word....
> 1111101001010100110101111
> again..
>
> If I lower the volume to
> 000000000000000000001111
> (which will sound very similar to 1111)

Not similar, the same. 000000000000000000001111 is exactly the same as 1111!

> Youll notice I still have 120db of headroom. I can increase the volume without clipping. <

No, because after I reduced the volume I then raised it back up again. So I converted this:

1001 0111 1011 1011

To this:

0000 1001 0111 1011

And then back to this:

1001 0111 1011 0000

> A really QUIET 24-bit sample is NOT THE SAME as a 4-bit sample. <

Sorry, but you are wrong. If you reduce the volume such that the highest 20 bits are now zeros, then all you have left is a four-bit sample. Do you think that raising the volume on that sample later will somehow restore the original higher data bits?

> ask anyone whos waiter accidentally charged him $200 instead of $20. Just because the "2" is the only active digit. <

That is also wrong. 20 dollars is the same as 020 dollars, just as 001111 is the same as 1111.

--Ethan

 

[Ethan Winer]

Teach,

> i just wanna see if other guys can hear the difference between them <

By all means post it there too. I'd love to have some of those guys weigh in on this.

--Ethan

 

[Slackmaster2K]

Ethan, but both you and camn are talking the same talk, underneath the surface anyhow.

If you have this 4 bit sample:

1111

And you throw it at a 16bit converter, you *don't* convert to:

0000 0000 0000 1111

You convert to:

1111 0000 0000 00000


Ethan, I think that what you're trying to demonstrate is this:

Start with a sample: 1011 0011 1001 0001

and turn down it down 24db: 0000 1011 0011 1001

and then turn it back up: 1011 0011 0011 0000


Bing, you lost a little bit of resolution, but can you hear it? In this case, the difference between the original and the processed sample is

0000 0000 0000 0001, or just 1, which corresponds to some arbitrary level between -93db and -90db.

How important is that bit? Let's say you just decide to call it noise, and let it fluctuate back and forth between 0 and 1. That means that you've got obvious crap down at -90db. What's the noise level of your soundcard, and of your amplifier, and all the sources you're recording? Probably above -90db.

Let's say that your realistic noise floor is at -70db. That means you can damn near toss off 4 of your least significant bits unless the noise you're recording is desirable.


Now let's look at that same example with a 24bit sample:

Start with: 1011 0011 1001 0001 0101 1001

Turn down: 0000 1001 0011 1001 0001 0101

Turn up: 1001 0011 1001 0001 0101 0000

You've now maintained your resolution down to -120db, compared to -90db. Does it matter? Hmm..



You know what I thought the big clincher would be? The fact that you've got 8 MILLION voltage levels to choose from between 0 and -6db in a 24 bit system. In a 16bit system, you have only 32 thousand. And so on down your range. I really thought that would make a huge amount of difference....especially when you start piling up 44 thousand samples a second....kind of like the difference between 32bit and 16bit color...the difference is noticable until you get into smooth gradients (for instance), at which point the difference is totally obvious.

HOWEVER, I am now starting to think that perhaps the space betwixt the points is really what's important when representing sound. After a certain amount of resolution, it's probably the clock and the accuracy of the sampler that has the biggest impact on sound quality.

Indeed, I can only hear the difference between 16 and 24bit at the extremes. In fact, I created an exact duplicate of a project in which all the source files had been recorded at 24bit (on a good system too, not my crappy stuff)....we're talking 24 tracks with loads of processing....limiters, trueverbs, etc. The difference between the two mixdowns was extremely minimal. In fact I used wavelab to create a "difference" file, and the only differences were WAY down like -80db...I couldn't see them no matter how hard I zoomed in and I had to crank the volume until I got sick of cranking it anymore.

I think that in order to truely appreciate the difference the rest of your equipment and your room must have to be in tip top shape.

Now I haven't actually RECORDED an entire project at 16bit and at 24bit. That could certainly be where the differences are. Consider tracking with somewhat low levels on a 16bit system vs a 24bit system. Technically the 24bit system will respond MUCH nicer to low levels. In fact a 24bit system can represent -48db as well as a 16bit system can represent 0db. But in that case the physical crud introduced by your system might make that less of an issue.

OR, perhaps it is unfair to record 16bit samples with a 24bit card.

Now I'm not saying that people shouldn't consider bying 24bit cards. Better cards are just going to be 24bit and that's that. Windowman makes some good points, but rest assured that the difference in sound quality between a Delta card and a Soundblaster is instantly recognizable, even by the average joe....even by my girlfriend! Perhaps 16bits is all the average home recorder needs to be happy, but that doesn't mean that just any old 16bit card will give you the sound quality you're after. A soundblaster sounds fantastic for $30, but it's very easy to outgrow.

Slackmaster 2000

 

[windowman]

Just one quick comment. I think SoundBlaster suffers from something that a lot of manufacturers do in that they started out with a product that wasn't very good. Then when they got a good product people were already biased against them and figured they would never produce anything worthwhile. Slack mentioned a $30 SB for instance. Well, I remember when they did make $30 cards and they weren't very good. In fact they only played back at 8 bit and had a noise floor in the 70's (I think.) However, the SB "Live" series was the first attempt at a more serious card based on the same converters (I'm pretty sure) that were used in the much ballyhooed EMU cards. Now they were full duplex and 16 bit both ways and had a SNR well into the 90's. But people still remember their previous cards and how bad they were.

Peavey, Crate, and others have done the same thing. By the time they came out with good equipment they already had a bad rep for producing inferior stuff and nobody had anything good to say about them.

Just thinking out loud really.
~~~~~~~~~~~~~

And as to the CD (redbook audio) waves on albums versus Windows PCM etc, I really don't know but I think that redbook waves are only different in that they put some idenitifer at the beginning and/or end of the wave files, so essentially they are the same as the PCM waves you started with. At least that was always my assumption. I could be very wrong about that however.

 

[Slackmaster2K]

I was actually including the Live!, which is in the $30 range (if you look hard). It's not a bad card, mind you, but stepping up is an instantaneously gratifying move. There's a lot of things to consider when designing a converter, and a lot of places to spend or skimp.

A digital system is very much like an analog system in that respect. Just as one tape deck can sound better than another, one CD player can sound better than another. My stereo CD player (a fischer) sounds fine on its own through my system, but playing CD's via DAE through my Delta card is another experience altogether. Much more satisfying sonically, although sort of a pain so I usually just use the standalone player.

Digital is fantastic for perfect storage and cheap/fast manipulation, but as long as you have to convert those bits back to an analog signal (or vica versa), you're going to run into the same *kinds* of problems you see in an analog system (e.g. "this doesn't sound as good as that"). I only mention this because much of what you hear in the marketplace would have you believe that all digital devices are equivalent because digital is "perfect". Only the medium itself is perfect. Recording and playback systems are subject to the same scrutiny that analog playback/recording devices are subject to. In fact it's interesting that both analog and digital devices share the same theoretical model of perfection, in that a perfect analog device would sound exactly the same as a perfect digital device, which would sound exactly the same as the source.



CD Audio is not written to disc in the same manner that CD data is written to disc, but in a perfect world, yes, an audio track is the equivalent of the original wave file. But if the error rate of the disc exceeds the maximum correctable error rate (due to a bad burn, scratches, dust/dirt, etc), then playback quality can suffer and the only way to judge it is with your ears....thankfully a lot of errors take the form of skips & pops. Now if you copy a wave to a data CD, you can rest assured that you're either going to retrieve a perfect copy of the original wave, or no copy at all.

Slackmaster 2000

 

[atomictoyz]

Ho Num..no one answered my questions...and Im still waiting...

Isn't there another piece of this missing....as far as the mathmatical precision of the recalculations during the processing. Maintaining the highest bit rate until the very last second.

There is some good reasoning to the quality of the playback system. Most mastering houses have such high quality gear that when they playback a 16 bit CD verses a 24 SACD or 24 bit AIFF, the bit rate comparison is obvious. What about the converter quality issues..24 bit linear ,16 bit linear....non linear converters....

Peace,
Dennis

 

[Slackmaster2K]

Well you know I don't think that maintaining high resolution is really an issue here. Whatever software you use is going to convert the 24 or 16bit data to some sort 32bit floating point value (we can assume 32bit because that would be most efficient on a typical PC platform). The only time it's going to spit out a 16 or 24bit number is when you're playing back or mixing down (e.g. the end of the line), or sending data out to an external device for processing.

Now if you are going to create a mixdown and then process that mixdown in another application, then conventional wisdom would say to mixdown to the highest bitrate possible. HOWEVER, if indeed 16bits is all the fidelity you need out of your system, then creating a 24 or 32bit file won't do you much good, especially since the mastering software (or whatever) is simply going to convert to its internal 32bit format and yada yada yada.

So the question still remains, when is 24bit precision necessary? Is it more important during the actual tracking process? I performed Ethan's test with my own source files (recorded analog from a CD) and could hear no audible difference between 16 and 24 bit, even after processing (huge level changes, reverb, etc). I also converted an entire 24bit project to 16bit and created a 16bit mixdown (there were LOTS of effects) and could not tell the difference between the two. The difference file I created with wavelab was at such a low level that it was way under the noise floor of my amplifier, which isn't real noisy, but probably not studio quality.

So it begs the question...what kind of gear do you need to hear 24bit resolution? Or perhaps it's an experience thing.

I know for a fact that plenty of professionals have moved to 24bit systems. If they say they benefit from it, then I'm not going to question them. They spend the real money, and their livelihood is on the line. There's obviously going to be a huge difference between a $1000 home setup and a $250,000 studio setup. If a professional engineer can make better mixing decisions when working with 24bit data, then he should be using a 24bit system.

Really there's a whole shitload of stuff I can't hear. Noise shaping, dithering, all that crap....it's so subtle and I don't have the gear or the ear to hear it.

I thought I was hearing the difference between 24 and 16 bit, but what I was hearing was the difference between ok converters and better converters.

Slackmaster 2000

 

[Hippo]

Its a straight forward challenge download trust your ears and reply!! simple, why are you all so frightened!!

Hippo