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Did you ever wonder what the difference was between bit depths?
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mwright137
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I made this a while ago after a professor was talking about the difference between bit depths.



As you can see, the difference between 16-bit and 24-bit is 65,536 vs. 16,777,216 levels to represent the 5V signal. Kind of amazing when you think about it.

Another way to think about it is 24-bit has 256 steps in between each step of 16-bit. Why would you record with 16-bit?

This message was edited 1 time. Last update was at 05/05/2014 13:20:06

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cristofe
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This sums it up nicely I think.........


What is bit depth?

Sample rate determines the frequency with which the system measures the volume of the audio. Bit depth determines how many different volume measurements the system has to work with.

In other words, if you think of the audio as being measured by a ruler, the bit depth is how many notches that ruler has. Some rulers only measure in whole inches (low bit rate), while others allow you to measure within one-sixteenth of an inch.

A ruler with more notches allows for a great number of measurement options, and therefore a more accurate measurement.

Comparing Bits to Inches
Okay, so the higher the bit depth the more individual measurements we can achieve. How does that relate specifically to recording?

If you’re recording at 44.1 kHz, then you’re telling your analog-to-digital converter (i.e. your audio interface) to take a volume measurement of the audio once every 1/44,100th of a second. How does it measure the volume? In bits.

1 bit = 6 dB

“dB” stands for decibel. It is logarithmic measurement of volume. If you increase the level of a signal by 6 dB, it will sound twice as loud.

So, for our converter to measure the signal at 2 bit rather than 1 bit, it needs to be twice as loud.

The 16-Bit Ruler
Digital systems don’t have “in between” measurements. Everything is cut and dry in the Land of Didge (shout-out to Slau).

So, the smallest unit of measuring volume in a digital system is 1 bit. There’s no 1.5 bit or 1.42983003 bit.

This means that in a 16-bit system, you have 16 notches on your ruler. 16 potential measurements for your audio. That may not sound like a lot, but keep in mind that these measurements are being taken thousands of times per second.

Alright, we said that 1 bit equals 6 dB of dynamic range (or volume). What is the dynamic range of a 16-bit recording? The answer is 96 dB.

96 dB? That’s great, right? Sure it is…in a perfect world.

Noise Floor
The problem you run into is noise. Every audio system out there has some amount of inherent noise.

In other words, no recording system is perfectly quiet. The electrical components generate a low-level noise. Each piece of your system contributes to the noise party. All of this noise adds up, and it’s called the noise floor.

This doesn’t even take into account any room noise that might get picked up by a microphone.

The noise floor essentially “steals” away some of your dynamic range. Let’s say that all the noise added together was 18 dB. That’s 3 bits.

Since this noise occupies the bottom 3 bits of your system, the level of your audio needs to be recorded ABOVE 3 bits (or 18 dB), or it will be lost in the noise. So instead of having 96 dB of dynamic range, you realistically only have 78 dB (or 13 bits).

The gap between your recorded signal and the noise floor is getting smaller. This means that if you don’t record your signal loud enough, you’ll end up hearing this noise in your recordings. On the flip-side, if you record your signal too loud (to stay well above the noise), you’re in danger of clipping.

24-Bit to the Rescue!
Enter 24-bit recording, super-hero cape blowing in the wind.

Now, instead of giving your converter 16 measurement options, you’re giving it 24. And if you kept your calculator our from earlier, then you know that 24 bits x 6 dB = 144 dB dynamic range!

An audiologist will tell you that our ears aren’t even capable of hearing a full 144 dB of dynamic range. However, having this much available dynamic range allows you to create greater separation between the recorded audio signal and the noise floor.

When you add in the 18 dB of noise we have in our make-believe system, and you drop the usable dynamic range down to 126 dB, you still have a TON of breathing room left.

Check out this diagram:





As you can see, the 16-bit system is still fairly close to the noise floor. The 24-bit system, however, towers above the noise floor, making it much less of an issue when recording.

In a 24-bit system, you don’t need to record the levels super-hot, because you’re signal is not nearly as likely to drop down into the noise floor. This leads to better sound quality, less noise, and less stress when recording.

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CTStump
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Which goes to prove that a 32 bit mix resolution(software not hardware i.e. internal resolution) is more than enough considering most recording is done at maximum of 24 bits these days. when you see the range which by the way goes both ways(above and below zero on the wave scale) there is more than enough dynamic range to cover even compositions like orchestral recordings. The only thing gained at a higher resolution would be less quantization errors in plugin processing, again probably beyond the audible range of most average listeners.

There really is no audible noise when the floor is pushed that far down in 32 bits and in some respects 64 bit mix resolution is in my opinion overkill.
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mwright137
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The reason you would want 64-bit resolution for intermediate processing is when you multiply/divide numbers, the result is generally a number with more significant digits.

Multiplication is easy. Ship bits and look at digits. Say your system can only process 3 digits. That's fine if you multiply 9x9 to get 81. But what if you multiply 123x456? They're both well within your 3 digit system, the the result of 56,088 is well over your 3 digit system. You need a 5 digit system to store that intermediate result.

Then look at division. An easy one we all know. 1/3 is a continuing decimal representation of 0.333333333333... How far out are you willing to go to keep your precision? Using only 3 digits as above, your result is 0.333. Using 5 digits it's still only 0.33333. That's close, but you're losing a LOT of information, especially if you then multiply that result.

Then combine many multiplications and divisions in a single computation and the rounding errors add up.
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CTStump
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When you sum up the rounding errors even at 32 bits precision after they multiplied umpteen thousands of times over would the errors be that noticeable to the average listener, probably not in the grand scheme of things.

Sometimes our own over critical ears(and minds) get in the way to what should be an exceptible mix. "If it sounds good it is good" and worrying whether you got enough bits to cover rounding errors(even at 32bits) shouldn't be one of the concerns on the way to a great mix.

At least that's my story and I'm sticking to it.

This message was edited 1 time. Last update was at 05/05/2014 17:46:25

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mwright137
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I agree - you might not hear the difference. But if you have the ability to process the intermediate steps at 64-bit, the only reason I see NOT to is if it is crashing your system.
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dgkenney
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Thanks for clearing that up for me. I thought bit depth determined how much you could capture. Like in 16 bit you could only do three chords such as C F G but in 24 bit you could expand it to C Am F G. This will really open my horizon in song writing.

Dan
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mwright137
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Always a comedian in the crowd. You know, some people DON'T know this stuff. Especially if they're just starting out.
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cristofe
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dgkenney wrote:Thanks for clearing that up for me. I thought bit depth determined how much you could capture. Like in 16 bit you could only do three chords such as C F G but in 24 bit you could expand it to C Am F G. This will really open my horizon in song writing.

Dan


LMFAO!!

Always a comedian in the crowd. You know, some people DON'T know this stuff. Especially if they're just starting out


Judging by many posts I've read....a LOT of people don't know about it.

Sometimes our own over critical ears(and minds) get in the way to what should be an exceptible mix. "If it sounds good it is good"


There's a lot of truth to that too. I wouldn't to go back to purely analog recording but there's something to be said for having to mix with JUST your ears.

This message was edited 1 time. Last update was at 05/05/2014 19:24:06


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