Tracktion 4 Manual
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- 1 Introduction
- 1.1 Introduction 1: Navigating This Manual
- 1.2 Introduction 2: Digital Audio, Some Key Concepts
- 1.3 Introduction 3: MIDI Basics
Tracktion originated in the mind of Julian Storer, an English programmer with a love of audio. State- side Tracktioneers* will notice a distinctly British flavor to the user interface. To help you understand Tracktion better, the manual was written with a British accent (thank you to Adam Starkey), and many cups of tea. So sit back, imagine yourself watching the sunrise over Stonehenge (or sitting in an English pub if you prefer), and enjoy Tracktion!
|Visit our website www.tracktion.com to download,
purchase, and register your copy of Tracktion.
Hello, and welcome to Tracktion! If you have not already read through the Quick-Start Guide, may we suggest that you start there. The Quick-Start Guide is specifically designed to get you up and writing music with your new Tracktion software as quickly as possible.
This reference manual will hopefully serve as both user guide and formal reference for all of Track- tion’s options and features. To help you navigate, each chapter covers a single subject, or section, of Tracktion. These chapters are then broken down into easy to manage sections. Where possible, chapters will begin with a hands-on look at the subject matter, including best practice suggestions, and walk-throughs for common tasks. Detailed reference sections will make up the remainder of the chapter.
That said, Tracktion has been designed with the specific goal of being as easy to use and accessible to you, the user, as possible. As such, while you are free to read this reference manual from cover to cover, we are confident that you will find Tracktion so easy to learn that you will only need to turn to this manual when you have specific questions.
Conventions Used In This Manual
Keyboard shortcuts are referenced throughout this manual. They are signified by bold typeface, e.g., F1. Where multiple keys are used to create a shortcut, the + symbol is without bold typefacing, to sig- nify that the keys should be pressed together, e.g., SHIFT+S.
The following pages assume you have a two-button mouse. For Mac users with a single-button mouse, the right-click options are available by holding down the CTRL key whilst clicking. If you have a single-button mouse, you will find Tracktion far faster to use with a two-button mouse. Such mice are inexpensive and can be found at most good computer or office supply stores.
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 find 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 first, 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 benefits 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 floor.
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 file 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 finally 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.
Sample Resolution (Bit Depth)
Although perhaps a strange analogy, a thermometer is a good model for describing sample resolu- tion. Imagine that you have a thermometer which is graded from the freezing point of water through to its boiling point. The accuracy with which you can measure the temperature of a cup of tea would be dependent on how many marks there are on the scale. A thermometer whose scale jumps in incre- ments of 10 degrees would clearly be less accurate than a thermometer offering a scale in terms of single degrees.
So, how does this tie in to digital audio? Well, reading a thermometer is largely a digital process. That is to say, while there is theoretically an infinite spread of possible temperatures between freezing and boiling, if you were to record them, you’d be using finite approximations. The temperature may be 50.2 degrees, but you would write down 50 degrees. This is exactly what happens with digital audio. The number of tick marks shown between the minimum and maximum temperature can be thought of as the sampling resolution.
Figure I.2.2 shows what happens to a sine wave when the amplitude is measured. The first image shows the sine wave when only two states are possible, either on or off. The second image shows the same sine wave reproduced with slightly less coarse graduations. Finally, the third image shows how increasing the sampling resolution produces a greatly more accurate impression of the original sine wave. So, when people talk about bit-depth, or sample resolution, what they are in effect describing is how accurately an audio signal’s amplitude can be measured.
Getting back to that thermometer for a second, what happens if the temperature being measured exceeds the boiling point of water? Well, in short, the temperature cannot be accurately recorded, and you would have to log it as “off the scale.” If, for example, you were to heat a beaker of water to just above boiling, then allow it to cool, a chart showing temperature over time might look something like Figure I.2.3.
Because the thermometer cannot measure temperatures above boiling, a whole section of the chart has been cut off (or clipped). Exactly the same thing happens when audio is being recorded digitally. Any audio that exceeds the maximum recordable level is simply clipped which produces a very unmusi- cal form of distortion.
CD audio has a resolution of 16-bits. Modern sound-cards and audio devices can record at 24-bits or higher. A big advantage of recording at these higher bit depths is that you can reduce your input level enough to ensure that digital clipping is very unlikely to occur, while still maintaining a resolution that is greater than CD. Lowering the level may also help to reduce noise levels.
Sample Frequency (Sample Rate)
It is all very well having an accurate recording device, but recordings also need to be made fre- quently enough to be meaningful. If you were to take the temperature outside of your home, you would expect to obtain different results at different times of the day. If you were to look at your thermometer only at midday though, you only ever see one temperature, and you could be forgiven for thinking that it pretty much stays constant all day long. This is because your sampling frequency matches the fre- quency of the temperature cycle. To get a more accurate idea of how temperature changes throughout the day, you’d need to at least double the frequency of measurements, and take a second reading at midnight. In sampling terms, the need to record at a frequency at least double the highest desired fre- quency is known as Nyquist’s Theorem. It is also the reason why CDs are recorded at 44 kHz, when the human ear can only hear up to around 22 kHz.
The sample frequency, therefore, is quite literally the number of times per second that the amplitude of an audio signal is measured.
When choosing a sample rate to record and work at, it is usually best to simply opt for whatever fre- quency at which your work will be distributed. If, for example, you are making music, and intend to have it printed to CD, you should probably work at 44.1 kHz.
Tip: If you wish to work at higher frequencies, and render down to a lower frequency when your proj- ect is complete, it is probably best to work at direct multiples of your target sample rate, e.g., 44.1 kHz and 88.2 kHz.
Introduction 3: MIDI Basics
If you are unfamiliar with MIDI, then perhaps the best analogy to start working with is one of those old player pianos — the kind with a large roll of punched paper that allowed the piano to play itself. MIDI is a modern version of that punched roll; it tells an instrument what notes to play, and a little about how to play them. In fact it is from these devices that the term “piano roll” used to describe MIDI editors in se- quencers is derived.
A common misconception is to see MIDI data as being the sound. It is important to realise that MIDI is little more than a list of instructions that an instrument can follow. Much like a sheet of musical score, MIDI data by itself is rather abstract.
In practical terms, MIDI data is made up of three types of MIDI events: note events, controller events, and program changes. In reality these groups are not quite so clear cut, and there are other types, such as system exclusive (sysex) messages. For the purposes of working with MIDI in Tracktion though, the three groups above are all you really need to be aware of.
A MIDI note event tells an instrument to play or stop playing a given note. When a key is struck on a keyboard, a MIDI note-on event is generated. The note-on event tells any attached MIDI devices which note was played, and the velocity with which it was struck. The MIDI note is considered to be held until a note-off event is generated by releasing the key. Velocity typically corresponds to “loudness,” but it may also affect the timbre of a sound; consider the way a piano sounds when keys are struck hard.
Most synthesizer keyboards have pitch bend and modulation wheels that allow the keyboardist to add extra character to a performance. These controls generate controller events that typically are used to change some nature of a sound over time. The modulation wheel for example may add a vibrato effect to a synthesizer performance. Most controllers are known as “continuous controllers” as they maintain their current state without needing to be held. In the same way that the modulation wheel will physically stay where you leave it, so too will the control changes generated by the wheel.
Technically pitch-bend is not a continuous controller, but for the purposes of working with Tracktion, it can be regarded as one.
A program (commonly referred to as a patch) in MIDI terms is one of the different preset sounds available on a MIDI device. A typical synthesizer may be able to emulate pianos, organs, violins, and bass sounds. Each of these different sounds would be a program. A special set of controller events can be used to change the current program on a MIDI device, but Tracktion makes it even easier by offering tools and options to insert program changes into edits.
Many MIDI devices are capable of playing more than one instrument at a time. Such devices are referred to as being “multi-timbral.” A multi-timbral MIDI device may be able to play a piano part, a percussive part, a bass part, and a flute, all at the same time. In order for the device to know which instruments are expected to play a given note received from Tracktion, the instruments are assigned a MIDI channel.
You can think of a MIDI channel as being broadly like a radio channel. In the same way that an FM tuner may be tuned to a radio station, the instruments in the MIDI device will only respond to MIDI events that are transmitted on their channel.
Each MIDI clip in Tracktion can be assigned a MIDI channel, and it is this channel that the MIDI events in the clip will be broadcast on. To make sure that a MIDI clip is played by the piano, therefore, you would simply set the MIDI channel for the clip to match the piano’s channel.
There are 16 MIDI channels available for every physical MIDI output. It is not a rule, but it is convention that MIDI channel 10 is used for percussion.
Working With MIDI In Tracktion
You can enter MIDI into Tracktion either by recording a performance from a MIDI controller keyboard, or by entering the notes by hand. In addition, Tracktion features a handy hybrid of these two approach- es, called “step editing.” You will learn about MIDI editing in Chapter Four, and about recording MIDI in Chapter Five.
Because MIDI data merely controls an instrument, if you want to hear the MIDI data you will need a MIDI instrument capable of turning to the note instructions into sounds.
There are two types of MIDI instrument you can use with Tracktion:
You can use all kinds of external MIDI equipment with Tracktion. Tracktion can control and record your hardware synthesisers and drum machines, in addition to calling up patches on hardware effects processors.
Tracktion can support the use of software instruments (often referred to as soft synths). The most common type of software instruments are VST instruments, or VSTis. There are many VSTis available both for purchase and for free. Tracktion even ships with some to get you started. The flexibility and ease of use of these virtual synthesisers can stand in stark contrast to expensive, bulky, and often fiddly external equipment. As the quality of available VSTis grows ever closer to parity with classic hardware instruments, more and more musicians are adopting software synthesis as an important part of their sonic arsenal.