- With digital audio, we rely on our computers
to do an incredible amount of processing.
Sometimes the computer can run out
of one or more resources while trying
to do all of that processing,
resulting in slow performance or even crashes.
A little knowledge goes a long way
to help prevent that from happening.
Let's explore the differences between
the three main resources that a computer uses
and how they affect your computer's performance
with digital audio.
I've simplified these into generalizations
and rules of thumb.
The three main computer resources
are processing power or CPU,
memory or RAM, and Storage like a
hard drive or solid state drive.
Let's start with processing power.
That refers to how much math the computer
can do in a certain amount of time.
Everything a computer does is math.
When you move the mouse pointer,
the distance you moves adds or subtracts
numbers to the pointer's coordinates.
When you type or read text,
every letter is represented by a number,
and when the computer draws the letter on screen,
it looks up a bunch of other numbers
to know what shape to draw.
And when you record and playback audio,
the computer is the traffic controller for
thousands or millions of numbers every second,
and usually doing some kind of math on all those numbers.
For example, turning a sound up or down
in amplitude means multiplying or dividing
every single sample.
The computer's CPU or Central Processing Unit
is what manages all these numbers.
This computer's CPU is hidden behind this large heat sink.
Here's what it looks like exposed.
A CPU has one or more cores
where each core can work on a different
math problem all at the same time.
The processor also runs at a certain frequency,
usually measured in gigahertz meaning
billions of cycles per second.
Each cycle computes part of a mathematical operation.
The CPU's power is partly determined
by the speed and the number of cores,
but some models of CPU, especially newer ones,
are more efficient.
That is, the same math takes fewer cycles.
Because of that, different models of CPU
can have different amounts of processing power
even if they have the same number of cores
and the same speed in gigahertz.
In the digital audio realm, more processing power
means the computer can handle a
greater number of plugins.
It also allows for effects that are more
complicated in computer terms, that is.
For example, a simple effect might be a single echo.
In that case, the computer only needs
to copy samples to create the echo,
divide the copied values to make the echo quieter,
and then, add the echo shortly after the original sound.
But to do automatic pitch correction,
it has to do calculus, trigonometry,
and other advanced math that uses
much more processing power.
Besides processing power, the other two
main computer resources are memory and storage.
Memory and storage are often confused with each other
because both of them are places to keep information,
but they behave differently,
and they're used for different things.
Memory refers to working short term memory.
It's very fast to access, but temporary.
If the computer is turned off,
the contents of memory are lost.
Memory is also referred to as RAM
which stands for Random Access Memory.
Adding RAM can sometimes make your
computer faster because if you don't
have enough RAM to fit everything you're working on,
the CPU has to work on one smaller
piece at a time which slows it down.
But if you already have enough RAM
to fit everything, adding more
won't make the computer any faster.
Your DAS documentation will tell you
it's minimum RAM requirement.
Unlike memory, storage is archival.
That is, it's slower to access but permanent.
Information stays there when the power is off.
Storage refers to things like a hard disk
which records information magnetically
on spinning circular platters, an SSD
or Solid State Drive which uses a
different technology called Flash,
USB drives, usually using a cheaper version of Flash,
optical media like CDs, DVDs, and Blu-Ray discs,
and of course older technologies
like floppy discs and magnetic tape.
The size of the storage medium,
the storage capacity, not the physical size,
tells you how much information it can hold,
measured in bytes.
Each byte is made up of eight bits.
Audio takes different amounts of disk space
depending on the format.
For example, at 48 kilohertz and 24 bits,
audio takes more than eight million bytes
or eight megabytes per minute per mono audio track.
Information on a computer is constantly
moving back and forth between memory and storage.
When someone talks about saving a document,
it means copying it from temporary memory
to permanent storage.
Then you can use that memory for something else
or even power down the computer
without losing what you're working on
which is safely in storage.
Likewise, loading or opening a document
means copying it from the slower permanent storage
to the quick, temporary memory
so the CPU can work with it.
This is simple enough with something fairly small
like a word processing document
where it makes sense to load the entire thing
from storage into memory.
But audio projects are quite a bit larger and more complex.
Much of the time, when recording and
playing back audio tracks, the audio files
are streamed more or less directly
to or from the hard disk.
That means that the speed of your hard drive
or solid state disk is a big factor
in determining how many audio tracks
you can record or play back simultaneously.
Storage and memory come into play
for virtual instruments too, but in a different way.
Some virtual instruments use samples.
For example, a sampled piano where
each time you press a key, it plays back
a recording of a real piano playing that note.
Long term storage, especially a spinning hard disk
is often too slow to find and play back
those samples in time to respond to your key presses.
Especially if you're hitting a lot of piano keys at once.
In that case, it makes much more sense
to load all those samples into RAM
so that the computer has instant access
to them at any time.
Some software instruments use clever tricks
to play parts of the samples from disk
but in general, the amount of RAM you have
determines how many different sampled
instruments you can have actively playing at once.
Not all virtual instruments use sample recordings.
Instead of playing back prerecorded sounds in RAM,
those instruments synthesize their
sounds from scratch using math
which means that instead of using
memory or storage, they use the CPU's processing power.
One last note about storage.
It's possible for a computer to have
more than one hard drive or SSD.
In that case, it makes a difference
how you spread the work across drives.
For example, if you have two drives,
it would be most efficient to put your
audio recordings on a different drive
from your libraries of sampled virtual instruments.
Keep in mind, using two partitions on one drive
doesn't count for this.
Only separate physical drives.
Let's summarize how the three main
computer resources affect a DAS performance.
Your CPU's processing power determines
how many effect plugins or mathematically
synthesized instruments you can use at once.
RAM determines how many different
sampled software instruments can be playing at once,
and with storage, the speed of the drive
determines how many audio tracks
you can work with at once,
and the size determines how much it can hold.
With an understanding of the three
main computer resources you can make
informed decisions about computer
hardware based on your specific needs.