</p>
<p>
Any computer that you can buy today (since somewhere around the end of
- 2012) is capable of recording and processing a lot of audio data. It
+ 2012) is capable of recording and processing a lot of audio data. It
will come with a builtin audio interface that can accept inputs from
microphones or electrical instruments. It will have a disk with a huge
amount of space for storing audio files.
a sound is generated and when you can hear it. When the audio signal
flows through a computer, that means that the computer has to be able to
receive the signal, process it and send it back out again as fast as
- possible.<br />
+ possible.<br>
And that is where it becomes very important <em>what</em> computer system
you have, because it is <strong>absolutely not</strong> the case that any
computer can do this job well.
</p>
<p>
The latency that you want for working with digital audio is typically in
- the 1–5 ms range. For comparison, if you are sitting 1 m
+ the 1–5 ms range. For comparison, if you are sitting 1 m
(3 ft) from your speakers, the time the sound takes to reach your
- ears is about 3 ms. Any modern computer can limit the delay to
+ ears is about 3 ms. Any modern computer can limit the delay to
100 ms. Most can keep it under 50 ms. Many will be able to get
down to 10 ms without too much effort. If you try to reduce the delay
on a computer that cannot meet your goal, you will get clicks and
<dt><abbr title="Universal Serial Bus">USB</abbr> ports</dt>
<dd>If you are using an audio interface connected via USB, and sometimes
even if you are not, the precise configuration of your system's USB ports
- can make a big difference. There are many cases where plugging the
+ can make a big difference. There are many cases where plugging the
interface into one port will work, but using different USB port results
in much worse performance. This has been seen even on Apple systems.
</dd>
<dt><abbr title="Central Processing Unit">CPU</abbr> speed control</dt>
<dd>Handling audio with low latency requires that your processor keeps
running at its highest speed at all times. Many portable systems try to
- regulate processor speed in order to save power — for low latency
+ regulate processor speed in order to save power—for low latency
audio, you want this totally disabled, either in the BIOS or at the OS
level.</dd>
<dt>Excessive Interrupt Sharing</dt>
<dd>SMIs are interrupts sent by the motherboard to tell the computer
about the state of various hardware. They cannot safely be disabled,
but they can also take a relatively long time to process. It is better
- to have a motherboard which never sends SMIs at all — this is
+ to have a motherboard which never sends SMIs at all—this is
also a requirement for realtime stock trading systems, which have
similar issues with latency.</dd>
<dt>Hyperthreading</dt>