24bit vs. 16 bit?

S

swollenrod

New member
I have recently invested boo koo dollar into
computer recording. Got a pod, nice computer, burner, etc. Thing is I only have a stander pci sb64. Now I've read up on 24 bit cards and they sound nice. I just want to know how necsasary a 24 bit card really is. I mean I play garage rock (with class mind you) and for the most part, I see a big difference already from analog. I wanted to go to digital simply for tonal clarity, but as a good bit of us already know too much clarity can be a bad thing. This is what I am afraid of investing another 500 dollars for. Is this the only thing I will gain from a 24, or is there somthing I am not considering? I cant get a straight answer from any of the music retailers cause they want to make a buck. Not to mention they told me I couldnt even get started without a 24 bit. Any suggestions would be greatly appreciated... -ThE sWoLe-
 
the deal with bit depth is this... and this is a sad analogy... think of the amount of bits as volume control.. and each bit is a notch.. the more notches you have , the more control you have over the volume , because the gain on each notch of a 24 notch volume knob is a little bit less than that of the 16... think dynamic range.. 24 bit resolution can capture dynamic parts better than 16 bit can... now that ive read this over..i hope someone else can understand it..

i did my best...

- eddie -
 
Well I can elaborate a bit...

If you look at it from a mathematical perspective, 16 bit's will give you 2 to the 16th amount of discrete voltage changes, 24bit will give you 2 to the 24th " "...

Anyway. Bringing this into perspective. If you were recording a guitar with an 4 bit soundcard, you would only achieve 16 possible samples (a sample being a snapshot in time, the volume of your guitar (amplitude, which to your sound card, will translate into a distinct voltage level) of the guitar - over a given amount of time.

Time in this case is the sampling rate, which is typically 44KHz for every second of recording.

So, with a 4 bit sound card, recording at 44KHz/Second: In one second of guitar playing, when played back, you would hear 16 snippets of your guitar - not the greatest fidelity.

Now, with 16 bit you will hear 65536 samples of your guitar. - this is getting more realistic. 24 bit - 16777216 possible samples of a guitar. I guess this would be an improved resolution. Whether it's audible or not is the question.

Does that help at all?
 
Emeric - good explanation. And that is indeed the question, according to what I've heard - can I actually hear it? What's your understanding? Have you (or anybody else) actually *heard* a difference between 16- and 24-bit recording?
 
I feel that I must have opened up one of those great philosophical questions. Judging from the responses however, I think I got my answer. As I was being educated by the mathematics (which by the way Emeric, was very helpful) I asked myself... now am I a 16,777,216 samples per second kind of guy, or am I a 65,536 samples a sec. kind of guy? Seriously I don't know. Bigger seems the obvious choice here right?
Well, it seemed interesting to me that "hearing" the difference wasn't so much the question. So then maybe the more refined question should be posed like so... How many samples per second does it take to get to the center of a tootsie roll pop? Furthermore, and possibly more importantly (depending on how many drugs your on when you read this) how many samples per second does one need of that frequency we call sound? Right now it appears that I lack a good 16,711,680 samp/per sec. Now with practical mathematics that seems like a big loss, but then again I find myself asking: How much can a second of analog sound be spliced up and rerouted into the digital form? How many possible angles does it need to be bounced around and captured? Now I know this seems like I am just ranting, but consider it a good 500 - 1000 dollar question. that is after all what 24 bit cards go for these days.

-swole-
 
Not pickin' on you Emeric, but from where I sit your explanation sounds misworded. I think you meant "sample types" when you said "samples". And when you said you would hear 16 snippets of guitar, again 16 different snippet types at the sample rate is what's going on. And with 16 bit recording, you're not necessarily hearing 65536 samples; you're hearing as many samples as required by the sample rate and snippet length, with the samples drawn from a set of 65536 different sample amplitudes. Recording with a sample rate of 44.1KHz, there would be 44,100 samples recorded each second. The 4-bit sample size would dictate that there could only be 16 discrete amplitude levels represented by this sample size.
But more to the point:
SwollenRod could improve on that SB card markedly without ever leaving the realm of 16 bit/ 44.1KHz.
 
Your right Drstawl, my wording was a bit misleading. A few too many Henningers..

As an addendum. The sampling rate dicates the frequency range for the signal - 44KHz will give you a frequency range of 22KHz. The bit depth relates more to the resolution or accuracy of the signal. With a 4 bit depth, the signal can be represented by 16 different voltage variations, whereas at 16bit depth, the signal can be represented by 65536 different voltage variations over a period of time, in this case 1 second.

A comparison would be printing out a picture at 300dpi as opposed to 1200dpi. 1200dpi has a higher resolution, and is a more accurate representation of the picture.

Emeric


[This message has been edited by Emeric (edited 11-18-1999).]
 
Your right Slackmaster2K my analogy is too confusing. I would rephrase it, but it would just make matters worse. It is dificult to explain without drawings. :-(

[This message has been edited by Fishmed (edited 11-19-1999).]
 
Please note: I wrote the following to clear myself on this issue. I don't mean to sound like I'm accusing anyone else of being wrong. I'm pretty new to all of this crap myself. BTW, I just noticed that we seem to have a lot of engineers around here....makes me feel like less of a geek :)
----
Whoa, everybody but Drstawl is confusing me here.

Why do you keep using time in your explanations of bit depth? The number of "samples" per second should be dictated by the sampling RATE. In most cases 44.1khz. That's where the strobe light and image resolution analogies fit in.

When recording at 44khz, your guitar sound, for example, is being sampled 44,000 times every second. When you playback your recording at 44khz, you're hearing 44,000 samples per second which is pretty close to continuous. In the real world, you hear live sound as a continuous function. In the computer world, you're dealing with discrete functions. Think movies here. In real life you see images as light is constantly hitting your eye. At the movies, the light is only smacking your eye 24 times per second which can be thought of as a "sample rate" rate of 24hz.

Now let's talk bit depth in terms of the image analogy that was posted. Increasing the NUMBER OF COLORS can result in a more accurate picture (talking real-life pictures, not clipart or anything). A pixel in a 16bit image will be one of 65,000 colors. A pixel in a 4bit image will be one of 16 possible colors. This is analogous to the bit depth of your sound. Now, this has NOTHING at all to do with image RESOLUTION which is just as important as bit depth. Image resolution is simply the number of pixels across by the number of pixels down and is analogeous to SAMPLE RATE.

Now let's talk music. Say you record with a sampling rate of 2hz. That's two samples per second. yeesh. Now let's say that you record a one second bend on your guitar. What are you going to hear? A little blip at the start of your bend...then silence...then a little blip at the end of your bend. Increase the sampling rate to 3. You hear a blip at the beginning, middle, and end. The more you increase the sampling rate, the less silence and the more guitar...which is a good thing!

Bit depth in terms of music: think back to the color analogy. If you take a picture of your goldfish and scan it in as 4 bit color, then you only 16 possible colors to represent your goldfish. In real life when you're staring at your goldfish, there are millions of different colors hitting your eye that make up the overall "color" of the goldfish. When you try to represent all of those colors with only 16 variations, then you're goldfish is going to end up looking like a cartoon character. The same thing happens with your music. Higher bit depth helps to capture more of the subtlety of your sound. It will sound more real...more alive.

Need to think in terms of math? Sound is a wave form hitting your ear drum. A nice continuous function that moves "up and down" with time. Sampling that wave would be a process of cutting it up on the x axis. Let's say that you sample that wave 1000 times every second. That means that you take a sample at time 0.000 seconds, time 0.001 seconds, time 0.002 seconds, time 0.003 seconds, etc all the way up to 0.999 seconds. Great, that's a lot of samples. But what values did you aquire for each sample? Now we come to the Y axis (start thinking bit depth!). Let's say that our accuracy for measuring the wave is 1. Our data (don't worry about what it IS) might look something like: 1, 1, 2, 1, 2, 3, 1....etc etc up to 1000 values. That might be just fine according depending on your actual needs, but let's say that it's not. Increase your measuring accuracy to 0.1. The data might now look like 1.4, 1.9, 2.0, 1.8, 2.4, 3.0, 1.9... See how things start to clear up? Now increase the accuracy to 0.01. The data might look like 1.92, 2.01, 1.83, 2.48, 3.01, 1.92... Hmm, increasing our accuracy in this case didn't seem to help much at all because we still have some pretty big gaps to fill in! How do you get rid of the gaps? MORE SAMPLING! Sample that sucker 2000 times per second. The data becomes 1.92, 1.95, 2.01, 1.94, 1.83, 2.02, 2.48, 2.79, 3.01, 2.52, 1.92... Aha, it's starting to smooth out a little bit...not so many big jumps. Now sample the sucker 44,000 times per second. Holy smacks, the big jumps will disappear after which the only way to become even more accurate is to INCREASE THE ACCURACY. See how the two are intertwined and equally important? Accuracy in this case, if you haven't figured it out, would be BIT DEPTH. The number of times you look at a wave over a fixed period of time is your SAMPLE RATE.

To sum up this big giant mess of a post: Sample Rate is the number of times you take a "measurement" of your sound every second. Bit Depth is how accurate each "measurement" actually is.

Bit depth without a high sample rate is useless. High sample rates without any bit depth is just as useless.

What's TRUELY important is how well you are able to recreate the original sound. Your computer isn't going to store an infinite number of samples at an infinite bit depth. But at some point it's just not important anymore because your ear, like any tool, is limited in accuracy! Just like the movies fool your eyes into seeing Pamela Anderson's boobies bouncing around in front of you, your CD player fools your ear into thinking that Tad is jamming in the corner of your room.

So this of course beggs the question: HOW MUCH DOES IT TAKE TO FOOL THE HUMAN EAR? You could make a soundcard that would sample 100,000,000 times every second at 1024bits. Holy crap that'd be the best soundcard in the whole world right? Well, I suppose, but it probably wouldn't sound any better than the current top of the line 96khz 24 bit soundcards or whatever.

Everything in your recording lineup is a tool and tools are only as accurate as humans can make them. The only thing that's actually REAL is that little vibrating string on your guitar. Cool.

Welp, I just made all that crap up. Please let me know if it's wrong.

Slackmaster 2000

[This message has been edited by Slackmaster2K (edited 11-18-1999).]
 
My two cents worth (and that's canadian... :)

Yes, you can hear the difference between 16 bit and 24 bit. That's the difference between CD and DVD (never mind the sampling [as opposed to sapling] rates, although they account for some difference, it isn't very significant).

William Underwood

[This message has been edited by cwillu (edited 11-24-1999).]
 
And I thought my explanation was confusing.

Time is critical because often this is a plot of time(frequency) and voltage(amplitude). Over a given period of time, your guitar is going to be represented by: An inaccurate representation of the signal or a better representation. All depending on the bit depth.

I guess the printer analogy was not a good one. I can't get the explanation across. I'm sure there are some good sites out there.
 
Heh, this is getting ugly. I don't really want to argue or anything...but I would like to understand what it is you're saying.

Bit depth is totally independant of time, correct?

Your guitar is sampled a certain number of times every second. This is of course very important. The bit depth, however, is simply the quality of EACH of those samples, regardless of how many there are.

I think that a good analogy might be film. Think of those great old silent movies shot back in first days of motion pictures. Notice how they kind of appear to be blinking and the image quality is pretty poor? This would be an example of a low sample rate and poor "bit depth". In other words, the cameras didn't take enough pictures per second to create nice smooth animation and the quality of each picture was poor. Now think of your brand new home video camera. That'd be a good example of a decent sample rate since the animation is nice and smooth, but the quality of each image is only *good* (e.g. acceptable "bit depth"). Finally, think of the average movie to come out of Hollywood these days. There you have a great example of good sample rate and great quality per sample.

So, the old silent movies would represent recording music at say, 8khz x 8bit. Your home videos would represent music recorded at 44khz x 16bit. And the Hollywood film would be 44khz (or better) x 24bit.

Does that work? I think we're saying the same thing.

Slackmaster 2000
 
Ok so I get it now...

Goldfish multiplied by pamela Anderson's Boobies (when bouncing) are the direct result of the optical illusion given by any 44 Khz strobe light during a math test. Unless you have 24 bit depth then cartoons are required for better resolution.

Now that I have an engineering degree (just kidding guys, I appreciate the help) can someone tell me how many samples per second I need to make (and here is the kicker) a "good quality" home recording. It doesnt have to be the crispest or the clearest. See to me Slack hit somthing right on the nose.
Think of a movie, 24 frames a second. Our eyes can handle much more than that, but alas we dont complain, just ask the guys at sony if they are getting any complaints on their tv sales as of late. Technology is somewhat of a placebo to a lot of us still. Example... If i get the new 600 megahertz computer I will be more powerful than everyone. Not truw, I/O bus speeds and wire technology impeeds on our full capacity for that technology, alas hindering that "really fast chip." But still we must have, must have must have. Point is, (and I may be wrong, but this is what I was asking originally) is 24 bit depth a nesascary thing? Cant I get clarity and quality sound from a 16 bit card? At what point exactly is the human ear decieved? 65000 samples per second seems like a lot to me. do I really need millions? Think about it?

Thanks -swole
 
You summed it up very nicely in your one sentence.

"Your guitar is sampled a certain number of times every second. This is of course very important. The bit depth, however, is simply the quality of EACH of those samples, regardless of how many there are."

That's pretty much it.

Swollenrod: With 24Bit becoming somewhat of a norm on most of the recording cards coming out, I would just try it and see what you prefer. 24Bit is going to take more harddrive space of course, this is one reason I have not tried it. I may try some recordings with the new 24bit drivers for my card and see if I can tell any difference.

Emeric


Emeric
 
Swollenrod:

I hate to beat this to death but I still don't think that you've quite got it. You're not taking 65,000 samples per second, you're taking 44,000 samples per second regardless of the bit depth. That's assuming that you record at 44khz. For the sake of discussion, if you get a 24bit soundcard you're still only going to be taking 44,000 samples per second (although better sound cards can sample at higher frequency).

Stop thinking "frame rate" and start thinking "frame QUALITY". It's my guess that you can probably tell the difference between 16 bit and 24 bit soundcards once you get the ear for this stuff.

In my own situation, I don't care that I'm "stuck" with a 16 bit card because there's so much low-quality junk BEFORE the card (cheap mixer, cheap amp, cheap cables, etc) that at 24bits I'd just have a really hi-fidelity bad sound. :)

You can definately make music with cheap equipment that sounds just great. I'm extremely happy so far. I suppose that if you get to the point where your stuff starts to sound professional, then it's time to start investing in professional equipment.

Slackmaster 2000
 
My 2cents, and that's about what it is worth.
From what I have been told from those who quote unquote are in the know. In the studio you want to keep your recording in the 24 bit realm as long as possible. Once it is put on CD it is back to 16 bits.Windows is only capable of 16 bit recording and all CD's are recorded in 16 bit.The idea is to mix and fine tune your sound in the 24 bit world for the best possible results in mixdown...Or so I've been told
Here's a link to an article that touches on some of the benefits of 24 bit recording. http://www.prorec.com/prorec/articles.nsf/files/4AE9C107C78E706886256688000FBE08 There are also many more articles and info at this site for inquiring minds... Hey by the way when does one become a "full" member this junior stuff really bugs!

[This message has been edited by TAE (edited 11-19-1999).]
 
TAE: You need to post 20 (25?) times then you get the Full Member title, looks like you don't have far to go..
 
pragmatic (adj) 1 treating things in a sensible and realistic way; concerned with practical results

But can anybody actually *hear* the difference between 16-bit and 24-bit cards. One Canadian (cwillu - yo! m'man!) says yes (I like the way you spelled sampling 'sapling' - it's all those maple trees up there, right?). But Cwillu compared CDs and DVDs, and since DVDs are video, I'm still not sure.

Can we set this up? Can we (or somebody here) record something on a 16-bit card, and record the same thing on a 24-bit card, and then report or post the difference?

Until then, we're just talking.
 
I don't think that posting files to evaluate the difference between the two is a vialble option. Once mp3 compression takes hold of your audio, the difference between 16 bit and 24 bit is no longer an issue. I think my dog can tell the difference though, hang on I'll ask him.......................... ..........................................
no luck there, he just mumbled something about more pizza crust.
 
Yeah the disk space thing is really something to consider!

I just did some quick calculations.

1 min at 96/24 ~ 17.28MB
1 min at 44/24 ~ 7.92MB
1 min at 96/16 ~ 11.52MB
1 min at 44/16 ~ 5.28MB

Kind of interesting there in the middle. Would you choose a high sample rate or a high bit depth?

I'd like to see some real-life comparisons too, but it's really impossible. Remember when CD's came out and everyone was up in arms claiming that vinyl sounded so much better. I didn't think so. This is all too subjective and I don't think that posting mp3 comparisons would help much because mp3 is too lossy. Hmm...

Like Emeric said, most good recording soundcards are 24 bit anyways...so I'm not sure what the concern here is. Get a card and try it at 16 and 24 and let your own ear be the judge.

Slackmaster 2000
 
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