User guide
Tracktion 4 Reference Manual
6
Introduction 2: Digital Audio, Some Key Concepts
Before we look at working with and recording audio in Tracktion, it may be helpful to look at a few of
the fundamentals of digital audio. If you have only recorded audio in analogue form before now, there
are a few rules you will need to unlearn, as well as few principles you may nd helpful to keep in mind.
Of course, if you are comfortable working with digital audio already, feel free to dive right into this refer-
ence manual.
Let’s get the most important rule of working with digital audio out of the way rst, because if there is
one thing you should take away from the short primer, it’s this:
You may be used to recording with analogue hardware, and if so you have almost certainly, at some
point, made recordings where the level meters are bouncing into the red areas. This is a habit you need
to break when working with digital. Whilst there are some practical and artistic benets to recording a
little hot with analogue recorders, when it comes to recording digitally, the level meters should be kept
below the red line at all times. Digital recorders are very unforgiving with audio that goes beyond the
maximum level, and such peaks will result in a most unpleasant kind of distortion. Aim to get your input
levels as high as possible without ever hitting the 0 dB mark, and if unsure, err on the side of caution.
Most modern converters work at 24-bit, which means you can leave a clear 3 dB of headroom without
in any way compromising on noise oor.
Figure I.2.1
shows the waveform of a simple percussive pattern. The waveform at the top is the
audio belonging to the left-hand stereo channel, while the waveform at the bottom belongs to the right-
hand channel. This image is basically a graph of amplitude and time, where amplitude is measured on
the vertical axis, and time is measured along the horizontal axis. If you know that this audio le contains
a single bar of a drum pattern, you can probably see that each of the high peaks represents an individu-
al percussive hit. Look closely at each of the peaks above and you can see that they all tend to reach a
peak amplitude very quickly. Once at their peak amplitude, they decay over a short period of time, and
nally fade to silence over a slightly longer period of time. If you think about the sound that percussive
instruments such as snares make, you should be able to see the correlation between the sound de-
scribed by the image, and the sound of an actual drum part.
That digital audio is a measurement of amplitude over time may not come as a surprise to you. After
all, that basically describes analogue recordings, too. Where digital does differ from analogue though, is
in how the amplitude and time measurements are made.
Figure I.2.1