Convergent evolution

The user interface of Pro Tools looks pretty much like a conventional sequencer with a track (or arrange) display, a tape-style transport control panel and a separate mixer window. Digidesign has developed its own terminology, with the basic arrangement or project being called a ‘session’ and all its associated audio, fade and EDL files being stored in the Session folder. This means you can easily backup or transfer a session between computer systems with the minimum of fuss, which is a requirement in the pro video world where the editing may take place in a variety of geographic locations. The segments of audio and MIDI displayed in the Pro Tools Track display or Edit window are called Regions, and are just a graphical representation of the contents of the Pro Tools EDL or session file. This window provides tools for altering the length of the audio regions, subdividing and looping the audio, as well as drawing-in track automation and determining how the tracks and audio data are to be displayed. There is also a text Region list that lets you either select and rename an individual region or drag it directly from the list into the session’s arrangement – useful if you are trying to find a particular audio take within the arrangement.

The Mix window lets you control and process the output from each track, and it is modelled on the familiar analog mixing desk channel strip. As well as the audio tracks, you can create additional control channels, such as a master level control and auxiliary (say, as effects returns), which then appear in the Edit window. These control tracks can be used to automate the mix channels by simply drawing in the volume profile or by Pro Tools memorising any changes you make to the levels during playback.

As well as the familiar channel fader control at the bottom of each strip, you can add audio-processing plug-ins to give either in-line or insert processing, say, dynamics control (for example, compression) or equalisation. Alternatively, you can send a portion of the signal to an auxiliary bus for ambient effects such as reverberation and delay. The supplied effects plug-ins employ Digidesign’s RTAS standard, which means they are non-destructive, so you can tweak them during playback. The number of plug-ins you can run simultaneously will depend on how powerful your PC is and how much of your PC’s processing power you want to allow Pro Tools to use (up to 85 per cent).

Open the Mbox

I have been looking at Pro Tools LE 6.4, which uses the Mbox external USB audio interface. The Mbox is a compact, two-channel interface designed to form the basis of an entry-level Pro Tools system. It has line-level, instrument and microphone inputs with selectable phantom power, as well as a line-level stereo analog output, S/PDIF (electrical) connections, and insert points that allow you to break into the audio signal path between the preamps and the analog-to-digital converters. This feature lets you insert a signal conditioner, such as a compressor or limiter, to tame wayward audio levels, and shows the professional approach that Digidesign has taken to the design of this unit. The interface is powered entirely from the PC’s USB port, which means that it cannot be connected via a passive USB hub. There are two headphone outputs with both jack and mini-jack sockets (although only one can be used at a time), with a separate volume control.

The analog-to-digital and digital-to-analog converters are 24-bit and can operate at either 44.1kHz or 48kHz sample rates. The USB port used is to the slower original 1.1 standard, which means that there is a significant latency delay when recording and monitoring using the Mbox. As with many interfaces of this type, there is also a zero latency monitoring facility that lets you mix the analog input signal with the computer playback so you can monitor as you record, avoiding the double delay caused by the signal having to hop down the USB cable to the computer and then back again.

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