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| | #1 |
| Gear addict Joined: Jun 2009
Posts: 479
Thread Starter | 16-Bits was never enough
Seriously though, how dare I say 16-bits wasn't enough? But "All of my CD's are 16-bit!" you say? "I bet he doesn't even know what a bit is!!" Do YOU know what a bit is? A better question, how does my computer process a 16-bit sample?! Ok theres about to be a lot of numbers on your screen. Get ready to bookmark this page, or run away... You already know a bit is a binary digit. It's either a 1 or a 0. You also aready know that a cd contains waveform represented by 44100 16-bit samples per second. So you know how many increments are in your sample rate, but how many increments are in your dynamic range?! I'm pretty sure most people say, obviously, 16 bits. CD resolution is 44100 by 16-bits. You probably like 24-bits because you know it has more dynamic range, and thus the potential to sound louder and clearer. So how many more increments do you have in 24-bit? You say 8 bits? Well, thats kinda like Nigel the guitarist saying that the volume knob on his Marshall TSL goes to 11. How much louder is it? One more. Of course. NOT! (anyone know how much blacker a black album cover can be?) So now we need to know how many whole number integers a computer can represent with 16-bit. For that, you need to know how to use the secret code of the binary number system. Wow, what a nerd I have become. Well heres a secret, nerds make better music than stoned out hippies! dfegad Stoned out nerds is another post altogether... You will have to take my word for it that 16-bits is: 16384 8192 4096 2048 1024 512 256 128 64 32 16 8 4 2 1 0 16-bits = 16384 decimal integer increments. So that means that a CD has a resolution of (44100 samples per second) x (16384 increments per sample). Yes you can simplify the math out farther, but that doesn't help out our case, because we want a static resolution, not dynamic. If you must know, its 722534400 bit increments a second, which is roughly 700Kbit per second per channel, or 1.4Mbit/s dynamic (streaming) resolution stereo. So we have 16384 volume increments in our dynamic range. May seem like a lot to some people...and it would be, in a perfect world. Since I suck at logarithms (and the point of my post is to embarass you publicly, not me fuuck) we won't be proving that most of those increments are in the top 1/10 of the decibel range. I can however show you how many "volume increments" there are per decibel on AVERAGE. Assume a 96db spl playback system is used. 16384 increments, divided by 96 decibels, is roughly 171 increments per decibel average...or almost exactly 6db per bit if you continue out the math. Already this sounds skimpy... you may not "hear" those 167 increments, but what is going on in the space between them? A ME's most loyal adversary and spiteful foe, DISTORTION!!! DUHN, DUHNNA DUHN! But wait, 171 increments is plenty for each of thel 98 decibels. The wiki post regarding this matter even says I get 6db per bit! Its wrong! Remember, when I said average? Really, the decibel scale is logarithmic. That means that the number of increments within each decibel isn't always the same. In fact it gets smaller and smaller, as you go down in db. It gets so small that the last bit is either 1 or 0 (1 actually means silence, 0 means that another bit is in use). That means that the number of increments from 0db to -6db is twice that of -6 to -12 db. All the detail is in the peaks of your audio, the part you spend all your time and money compressing the detail out of........ 16-bits isn't enough because really the bottom 8 bits of audio are distortion waiting to happen when you bring up the level....(again, I'll let someone else post the Log equation). A CD is just barely situated atop a sea of distortion...even more than a tape, but that shouldn't be news to a mastering engineer! PS: Maybe this post could go in the mixing forum instead, seems like it could be useful here as well... ...also yes you can hire me to write articles/essays for you...not to mention software... |
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| | #2 | |
| Lives for gear Joined: Jun 2009
Posts: 3,397
| Quote:
Is it possible to develop an alternative digital format with greater incremental resolution per dB? | |
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| | #3 |
| Gear addict |
None... none more black. Interesting and educational post, thanks! |
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| | #4 | |
| Gear addict Joined: Jun 2009
Posts: 479
Thread Starter | Quote:
Sure. Binary is easy. I should have labeled the columns. Here's a simple example of how to calculate decimal (base 10) numbers into binary (base 2). 4-bits can represent up to the number 7: 4 2 1 0 1 1 1 0 (That is, 1110 in binary is the number 7 in decimal) The number 5 would be: 4 2 1 0 1 0 1 0 (That is to say, there is one 4, zero 2's, one 1, and zero 0's. 4 + 1 = 5 ) The number 8 (in 8-bits) would be: 64 32 16 8 4 2 1 0 0 0 0 1 0 0 0 0 (So 00010000 is the number 8, which brings me to the next point...) Yes it is without a doubt possible to create another format, and it would be indeed be easier for a person to calculate (although it defintely wouldn't be real time) but computers work in binary, so every computer program is abstracted from binary operations. You would just be adding to the number of binary operations the computer would have to perform to represent and manipulate a waveform with decimals, thus reducing the performance of the sytem by a whole whole lot. It would kinda be ridiculous as if everyone said "two plus two" instead of just saying "four." Computers speak binary, so its easier for them to do math that way, even though its absolutely mindnumbing for their carbon based creators.... | |
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| | #5 |
| Gear addict Joined: Jun 2009
Posts: 479
Thread Starter | |
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| | #6 | |
| Lives for gear Joined: Jun 2009
Posts: 3,397
| Quote:
So I guess Intel/AMD better get moving on making some much, much faster computers. | |
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| | #7 | |
| Gear addict Joined: Jun 2009
Posts: 479
Thread Starter | Quote:
I'm sure 64-bit audio is on its way. All it takes is a major software industry standards upgrade. Imagine a 32-bit wasteland underneath a blisteringly clear 32-bit peak range! Creative distortion may be a thing of the past...and physical hearing capability may start to matter logarithmically more than it does already! The future of audio is what photographs were to paintings...I promise. Start saving your money for holographic projection speakers...er panels, er paint??!!
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| | #8 | |
| Lives for gear Joined: Jun 2009
Posts: 3,397
| Quote:
Also, on another note, does anyone know how to calculate the frequency resolution of digital? | |
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| | #9 | |
| Gear nut Joined: Jul 2007 Location: Melbourne, Oz
Posts: 117
| Quote:
And while the dB scale is logarythmic the , the encoding for CD is linear PCM. Mihaly. | |
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| | #10 |
| Lives for gear Joined: Aug 2005 Location: Norway
Posts: 1,741
Verified Member |
The first bit/first 6dB's is on or off. The next bit have two more choices added to that - four level options. The next one have 8 level options, and so on. Dividing total range by number of steps makes no sense. The frequency resolution is set by the sample rate. A sampled system can preserve all frequencies below FS/2. |
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| | #11 |
| Lives for gear Joined: Aug 2005 Location: Norway
Posts: 1,741
Verified Member |
PS: this discussion omits the fact that any digital audio system not using dithering is for all practical purposes a broken system. In a dithered system, dynamic range depends on the level of the dither noise - not on the available number of steps. A 16 bit signal with proper dithering gives about 120dB of dynamic range in the most sensitive frequency region. A 24 bit signal is only marginally better than that..
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| | #12 | |
| Lives for gear Joined: Jun 2009
Posts: 3,397
| Quote:
ie. Can a digital system represent the difference between 11000 hz and 11000.000000000000000001 hz? Where does the rounding occur? | |
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| | #13 | |
| Gear addict Joined: Jun 2009
Posts: 479
Thread Starter | Quote:
BTW, I program but I don't do a lot of bitwise operations, I'm still on the higher level GUI/DLL stuff. Always learn everyday what a dumbass I am in some way or another! ALSO, logarithmic scale represented by a linear value is still what I was talking about, just had it backwards... PS: I did tell everyone to think for themselves didn't I!!! And look ... Thank you! | |
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| | #14 | |
| Gear addict Joined: Jun 2009
Posts: 479
Thread Starter | Quote:
Dithering is filler for missing data... its a guassian blur effect, no? It was conceived to cover deficiences in dynamic resolution, correct? Can audio be captured and played back with more detail so that it more closely resembles reality? | |
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| | #15 |
| Lives for gear Joined: Jun 2009
Posts: 1,022
Verified Member |
It's a bit too easy to get caught up on the "stepped" image of the sample stream, you have to think of what comes out of the reconstruction filter after the DAC. The best way to think of it is as the original signal plus an error (an analogue system would be the same so long as you're talking about signals within its bandwdith you get the orginal signal, plus noise, which is an error). In a properly dithered sample stream that error is statistically random, i.e. noise, and the system maintains resolution below the LSB, you can hear below the digital noise floor just as you can below an analogue noise floor. So I'm afraid the original post is rather misleading. As a delivery system, 16 bits is probably adequate in most cases (it has a higher signal to noise ratio than vinyl), especially if we use higher resolutions in the preceding stages, but of course these days we can do better, it's a shame the shops are full of CDs and not DVD Audio. |
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| | #16 |
| Lives for gear Joined: Jun 2009
Posts: 3,397
| I don't think so. We're not talking about how it sounds, we're talking about how it exists in a computer, where there is definitely finite, quantifiable resolution.
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| | #17 |
| Lives for gear Joined: Jun 2009
Posts: 1,022
Verified Member | A sample stream can repreent any frequency below nyquist, with any phase relationship, if you change the frequency slightly or change the phase slightly then you change the instantaneous level at the sample instances.
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| | #18 | |
| Lives for gear Joined: Jun 2009
Posts: 1,022
Verified Member | Quote:
All audio systems have errors, analogue and digital, what matters is how those errors sound. | |
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| | #19 |
| Gear addict Joined: Jun 2009
Posts: 479
Thread Starter | Thank you! I know I made a rather large error in the original post, it was purely and simply haste. I practice drums, not binary, ya know! I'm learning programming and I thought I'd share some information. All these robots just came out of the woodwork all "invalid though, invalid thought" My opinion is still valid Mihal and Lupo, as was my description of digital media. I got my binary conversion wrong, and I'm sorry! I thank you for correcting me!
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| | #20 | |
| Lives for gear Joined: Jun 2009
Posts: 3,397
| Quote:
That's ridiculous. | |
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| | #21 |
| Lives for gear Joined: Aug 2003 Location: Hollywood CA
Posts: 2,625
Verified Member | |
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| | #22 |
| Lives for gear Joined: Aug 2003 Location: Hollywood CA
Posts: 2,625
Verified Member | |
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| | #23 |
| Gear addict Joined: Jun 2009
Posts: 479
Thread Starter | |
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| | #24 |
| Gear addict Joined: Jun 2009
Posts: 479
Thread Starter | Don't "oh dear" me, it rounds off the square wave which is composed of harmonic distortion in the analog world to a more suitable sinewave...it is pretty much a guassian blur that is generated by noise, as far as I can tell.... ALSO, I ALREADY ADMITTED TO THE BINARY MISTAKE! ENOUGH! WE GET IT! ITS OBVIOUS NOW THAT I LOOKED IT UP! LOL |
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| | #25 | |
| Lives for gear Joined: Jun 2009
Posts: 1,022
Verified Member | Quote:
The finite sample rate is not an issue with frequency and phase accuracy, the finite quantization error is, but in a properly implemented system it's no different from the limitation caused by noise in an analogue system. | |
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| | #26 |
| Lives for gear Joined: Aug 2005 Location: Norway
Posts: 1,741
Verified Member | |
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| | #27 | |
| Lives for gear Joined: Jun 2009
Posts: 3,397
| Quote:
Frequency in reality has infinite resolution within a given bandwidth. Frequency as stored in a digital file does not. | |
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| | #28 |
| Lives for gear Joined: Jun 2009
Posts: 1,022
Verified Member | True, but neither does freqency stored on a piece of analog tape, for the same reason, when you get below a certain level of difference, you get into the random error caused by noise, given an infinitely long piece of tape or an infinite digital sample stream, you would on average have the infinite frequency resolution, in the real world you don't, but nobody's noticed with tape yet.
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| | #29 | |
| Lives for gear Joined: Jun 2009
Posts: 3,397
| Quote:
This is a discussion about quantifying digital resolution, which I think is valuable, since it's rarely considered. | |
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| | #30 |
| Lives for gear Joined: Aug 2003 Location: Hollywood CA
Posts: 2,625
Verified Member | |
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