At the high end of the digital audio workstation market, in broadcast production, CD mastering, and video postproduction, there are dozens of manufacturers vying for a piece of the action. At the low end however, the Californian company Digidesign stands alone. Thanks to their emphasis on off-the-shelf computers and storage devices, Digidesign have managed to produce hard disk recording and editing systems at a fraction of the cost of systems like the Synclavier or AudioFile.

Originally known for feature-laden and user-friendly sample editing software, Digidesign took the plunge into hard disk audio recording last year when they released Sound Tools, a stereo hardware and software system built around a Macintosh II or SE computer. They followed it up with an Atari Mega ST version, and more recently with Audiomedia, an even cheaper version of the Mac system which gives 95% of the sound quality and 75% of the features, at 30% of the price.

Now comes Deck, a software package that allows not two, but four tracks of digital audio to be played back and mixed on a Macintosh II (an SE/30 version is expected soon), with full 16-bit/44.1 kHz digital fidelity. It requires either the Sound Tools hardware (the Sound Accelerator card and AD In analogue-to-digital convertor) or the Audiomedia card (which contains both inputs and outputs); a Mac with at least two megabytes of RAM and a 13" monitor; and a hard disk, fixed or removable, with an average access time of 28ms or better.

TAPELESS TAPE

Deck is modeled after the 'Portastudio'-type self-contained 4-track tape recorder/mixer, and works entirely in a linear manner. There are no cut-and-paste editing or pattern-and-track assembly facilities such as you would find in a sequencer or sample editor. The main screen contains four channel faders, pan controls, and buttons for Record, Solo, and Mute for each channel, and various sound-manipulating controls. There is an output section with vertical bargraph meters for each channel and for the stereo outputs, plus a pair of master faders. A transport section contains the usual 'motion' buttons, and several digital counters.

When a track is record-enabled — by clicking on the Record button — an input level fader appears, along with a bargraph input meter. Signal appearing at the Audiomedia card's inputs is shown in the meter, and levels can be adjusted with the fader. One or two tracks can be record-enabled at the same time. The input meters are not calibrated, but a horizontal line appears at the top if clipping occurs. (When using Sound Tools, input levels are adjusted and monitored on the AD In box.) Clicking on the master Record and Play buttons in the transport section of the screen starts the recording, as well as the main counter, and clicking on Stop stops it. The sound is recorded directly to the computer's hard disk, and stored immediately as a 'track' file.

You then click on Rewind or Return-to-Zero and record-enable another track (or two), while listening to the first track(s) play back. If you don't like a take, you simply go back to zero and do it again. With the Audiomedia hardware, you can listen to three tracks — or even four, in sound-on-sound mode — while you record, but with Sound Tools you can only monitor two tracks (although you can choose which two). When you replay a track, you can adjust its volume and pan position.

A fast-forward control moves you through the file quickly, and you can also 'scrub' the music by placing the mouse inside the real-time counter and dragging it left or right. The music will play, backwards or forwards, from about 10% to 100% of normal speed, depending on how far you move the mouse. In addition, you can store up to eight 'locate' points, and when you click on one of their buttons, the transport immediately jumps to that point. This works even if the file is playing at the time, which is a bit unnerving the first time you try it.

You can punch in and out on a track, setting the punch points in special 'Begin' and 'End' counters. You set these by playing the file or scrubbing in the main counter, and then clicking on the counter to capture the current time, or else you can scrub in the Begin or End counters themselves. The punch function is immediate, which unfortunately means that if there is signal present right at the punch point, it will produce an audible click or pop. Therefore, you should only punch on silence.

There is also a sound-on-sound function, which adds a layer of audio to a recorded track on the same track, while you listen to it (sort of like disconnecting a tape recorder's erase head while you record — anybody else remember trying that?). Since everything takes place in the digital domain, you can layer plenty of tracks without worrying too much about generation noise, although you do have to be careful not to let a track's level get too high. A loop function (also set in the Begin and End counters) allows instantaneous repetitions, with each loop allowing another layer to be added on, much like some sequencers.

The loop function is very versatile: it can be used without sound-on-sound to rehearse a live track; it can be used to record multiple takes without stopping and resetting the transport each time (a move that normally requires four mouse clicks); or it can be used with a punch, allowing you to do it over and over again quickly until you get it right.

"In a Deck 'session', you can import and play back MIDI Files... which have been created by any MIDI sequencer, while you record and/or mix the audio."

Deck also lets you bounce tracks, but this is an 'off-line' function: you pull down a menu to set up the bounce (you can bounce an entire track or just a selected region), and then the computer executes it without actually playing it. Unlike with tape, you can bounce a track to itself, and you can also bounce four tracks down to two. Again, because there is no generation noise, Deck lets you bounce many times without degrading the signal.

EQ AND EFFECTS

The software allows you to impose equalisation and time-based effects onto recorded tracks in a non-destructive way: the file on disk remains unchanged, and the effects are applied 'live' when the track is played. The effects are only available if you are using the Audiomedia card; the Sound Tools system, although it is more expensive, uses older technology that is not fast enough for this kind of real-time processing.

Each track can be assigned one of five EQ/effects combinations:

• In '2-band EQ', each band can be high-pass, low-pass, or band-pass, with adjustable frequency, gain (4-12dB), and bandwidth.

• 'EQ-Stereoise' combines one channel of parametric equalisation with an adjustable delay line that creates a copy of the signal, delays it by up to 23 milliseconds, and pans it to a point exactly opposite the current pan position for the channel.

• 'EQ-Delay' combines one channel of equalisation with an adjustable delay line (again, up to 23ms), that has feedback and wet/dry mix controls.

• 'EQ-Chorus' combines equalisation with a chorus module with adjustable depth, sweep speed, and mix.

• 'Mod-Delay' has no equaliser, but instead offers two delay/chorus modules, the outputs of which go to different output channels.

"Another clever use for MIDI is that the controls on the Deck screen can be mapped to incoming MIDI continuous controllers from a synthesizer or other device."

The controls for any of the modules can be moved while a sound file is playing, and an effect can be instantly defeated with a single mouse click. Command-clicking on a control displays a precise value for its current setting but, unfortunately, except for the equalisers' centre frequencies, these values are given as percentages rather than any meaningful units.

In a real-time situation the effects are non-destructive, but when you bounce tracks, they become permanent and are 'burned-in' to the new track. There are also three destructive effects provided, which are not available in real time but, like bouncing, work on the file offline: hum removal (based on either 50Hz or 60Hz line frequency), noise gating with adjustable threshold, and normalisation.

MIDI SEQUENCES AND CONTROL

Although several systems for combining MIDI sequencing and hard disk recording have been announced, Deck is one of the first products on any platform to actually appear that offers that capability in a useful and user-friendly way. In a Deck 'session', you can import and play back MIDI Song Files, either Type 0 (single track) or Type 1 (multitrack) which have been created by any MIDI sequencer, while you record and/or mix the audio. This gives you the capacity to have 32 'virtual' tracks playing along with the four audio tracks, all running in perfect sync. You can mute individual MIDI tracks or route them to different channels, and there are also some rudimentary MIDI recording and editing functions for altering the files after they are recorded, or for creating new files. MIDI Files recorded or edited in Deck can be saved and exported to other programs.

The most obvious way to combine MIDI and digital audio tracks is to record the MIDI tracks first in a sequencer, import them into Deck, and then overdub the audio tracks, but you can also do this the other way around. The program can produce a MIDI metronome, which you can use as a click track to record the audio to. Then you can import a MIDI File later, and as long as its tempo setting is the same as the metronome's, it will play back in perfect sync with the audio. (If it's not, the metronome can override the MIDI File's tempo setting.) Another clever use for MIDI is that the controls on the Deck screen can be mapped to incoming MIDI continuous controllers from a synthesizer or other device. Since it is impossible to adjust more than one control at a time with just a mouse, this provides a way for the software to operate more like a real mixer, on which you can move as many faders as you like simultaneously.

Setup is simple: press a 'Map' button, select a fader you want to have under external control, and then move the controller on your MIDI device (modulation wheel, foot pedal etc, but not pitch bend or aftertouch) that you would like to assign to it. Press the Map button again, and the assignment is confirmed. The fader you mapped can now only be controlled by the chosen MIDI controller. You can even assign multiple Deck faders to a single MIDI controller, so that your synthesizer's modulation wheel, for example, could control the volume on all four tracks simultaneously.

If you have a MIDI 'fader box', like the Lexicon MRC or J.L Cooper FaderMaster, you can assign several Deck faders to it and use it as a real-time control surface. Unfortunately, there is no scaling factor or directionality to the mapping, so a zero controller value will always result in the minimum fader position, and a controller value of 127 will always move the fader to maximum.

All of the MIDI data, including maps and the imported or created MIDI File, is saved as part of the Session File.

SYNCHRONISATION

Deck is designed to be a self-contained system, but it can synchronise to the outside world in a limited fashion. You can tell the program to start playing a file when it receives a MIDI Start or Continue command, or on a specific MIDI Time Code (MTC) frame, either of which can be generated from a SMPTE/EBU timecode track, provided you have the appropriate SMPTE-to-MIDI Sync or SMPTE-to-MTC convertor unit.

"Deck is very hungry for disk space... one track of 44.1kHz audio uses up about five megabytes per minute. Therefore, a five minute, 4-track piece requires a whopping 100 megabytes!"

However, Deck does not read Song Position Pointers, nor can you send it an MTC frame number later than the designated starting point — not only will it not calculate a timecode offset, it won't start at all.

More importantly, Deck does not sync continuously: once the Start command is received, it 'freewheels' according to its own internal clock. That clock is quite accurate, but if there are any minute speed variations in the tape that Deck is syncing to, it will not be aware of them, and will go on its merry way. Therefore, using Deck along with tape in a piece longer than a minute or so, or in a piece where phase accuracy between tape and hard disk tracks is required, is not recommended.

On the other hand, it will generate MIDI clocks, so synchronising an external MIDI sequencer to Deck will pose no problems at all, and it also generates MIDI Time Code, which could theoretically be used to drive a tape machine. However, even though the owner's manual mentions this as an option, there is currently no hardware available that will let you do it.

MIX AUTOMATION

Remember when mixing console automation required a dedicated computer? Deck does it with its eyes closed. Well, not really, but when you're handling four tracks of 44.1kHz digital audio, the extra horsepower you need to run a mix seems niggling.

At any point in a mix, you can take a 'snapshot' of the current position of all faders — levels, pans, and effects — and store it along with the current counter time. Up to 200 snapshots can be stored in a single mix. When you play a file with automation, as you encounter each snapshot the screen faders move accordingly, as if powered by an unseen hand.

You can add or remove automation events, and also move the snapshots around in time by clicking on an automation 'edit' button and adjusting the Begin and End counters. To ensure smooth automation moves, these counters can also be used to create a crossfade of any length between the previous snapshot and the current one.

A mixer state that might be used more than once during a mix (such as 'all faders down') can be stored in one of eight 'State' buttons, and recalled at any time, either while mixing 'live' or as part of an automation. Like MIDI data, all automation data is stored when a session is saved, and the automation 'track' can also be stored as a separate file, so that it can be imported into other sessions.

DEALING WITH HARD DISKS

Deck offers plenty of versatility in terms of handling files. As with most computer programs, you can save as many intermediate versions of tracks and sessions as you like, so even though you only have four tracks available to listen to at a time, you can have as many tracks as you want waiting in the wings, all perfectly preserved — theoretically, at least, you never have to erase or throw anything away. Imagine being able to strip a single track from a 4-track tape and set it aside for later use: Deck lets you do this with ease.

"The manual lists a number of popular hard disks which are simply too slow to work with Deck."

You can also 'Mix to Disk', creating a stereo Master file in Sound Designer II format which can then be played back with any compatible program, such as Sound Designer II, Audiomedia, Alchemy, Q-Sheet A/V, or Opcode's forthcoming Studio Vision, or even transferred to a sampler. Like track bouncing, mix-to-disk is carried out silently 'off-line', with all automation moves preserved, just as if you were playing the mix in real time.

All this versatility comes at a price, however: Deck is very hungry for disk space. When you save a session, you're saving at least five files: the session itself, and the four individual tracks. The session file is relatively small (it contains mostly MIDI and automation data), but the tracks take up a lot of room: one track of 44.1 kHz audio uses up about five megabytes per minute. Therefore, a five-minute, 4-track piece requires a whopping 100 megabytes!

A Master file will be the size of all four tracks combined, and if you want to save any backups or alternate takes, you'll need even more disk space.

To save on memory, Deck does allow sessions to be 'compressed', which reduces the storage requirements by 50%, but tracks in a compressed session cannot be equalised or effected, nor can they be exported to any other program. Furthermore, compressed and non-compressed tracks cannot form part of the same session, so you can't save space by compressing just one or two of the tracks. Compressed tracks can be 'decompressed', but there is a slight loss of fidelity in that operation, and the decompressed version, of course, now takes up twice as much hard disk space.

Deck is also impatient. When it wants data from a disk, it wants it now. Its requirements for hard disk speed are at least as stringent as Sound Tools', and the software really pushes both computer and hard disk to the very edge of their performance. The manual lists a number of popular hard disks which are simply too slow to work with Deck.

This list, surprisingly, includes Syquest removable drives, which are becoming increasingly popular among sampler users, and are consequently dropping in price. Digidesign says that they have discovered minor variations in speed between different models of Syquest drives (they are available under many brand names), and while some will be fine, others will not, and thus they chose to "err on the side of safety" in their recommendations. (My personal experience with a Microtech Syquest drive, once it was formatted correctly for my Macintosh IIex, was that it caused no problems.)

The speed issue aside, however, one Syquest cartridge can only store nine track minutes, so this may not be the best format for use with Deck unless you're doing primarily 30 and 60-second spots. If you want to work with long pieces of audio on Deck without sacrificing flexibility, you'll need an enormous fixed hard disk, plus an optical disk or tape drive for backup.

MOANS AND GROANS

Since Deck is stretching the performance of the associated hardware so much, and since it is such a new concept in personal computer software, there are bound to be problems. Fortunately, they are relatively minor. When audio is playing, the program is working hard to make sure it is handled properly, and so screen updates are given a low priority, with the result that the display becomes quite jerky, and moving a fader can feel like trying to grab hold of a live fish. Screen repaints are also exceedingly slow.

"Digidesign have made it clear that Deck is just the beginning for them in terms of low-cost multitrack hard disk recording."

When you are using a lot of equalisation on a track, it is easy to clip the audio. Since the level control is post-EQ, there is no way to compensate for this. Furthermore, the clipping markers in the level meters, while certainly necessary (clipped digital audio invariably sounds awful), are rather hard to get rid of. If you clip an input signal, the only way to clear the marker (so that you can try recording again) is to take the channel out of record mode and put it back in again, which is a pain. If you clip a track in a mix, you have to reset the transport to zero to clear the marker. That makes it impossible to isolate a trouble spot by just backing up a few seconds, adjusting the level, and trying again.

The effects modules are, unfortunately, no competition for even the most rudimentary external digital delay. The delays are not long enough to be really useful, and the control over them is not fine enough. Also, they are only available when you're doing a straight mix: they are all defeated if any track is record-enabled, or when you scrub the audio.

The MIDI implementation, while it works well as far as it goes, is not especially sophisticated. If a Type 1 MIDI File contains a tempo map, Deck will ignore it and play the whole thing at the initial tempo of the file, and it will also generate clocks at that constant speed. Type 0 MIDI Files containing tempo changes will play correctly, but the clocks will still come out at a constant speed.

NOT TO WORRY

On the positive side, Digidesign have a good record when it comes to fixing things, and so I suspect solutions to most of these problems will be evident in future revisions of the software. But Deck is already a very fine program. Although it is geared towards the semi-pro user, it offers several orders of magnitude more flexibility and fidelity than budget tape machines, and it will satisfy the true pro who is willing to operate within its relatively simple framework.

Deck is extremely easy to use: I worked with it for a week before I opened the manual (although I don't recommend you do the same). As a piece of software, it's reasonably priced, especially considering the hardware you need to run it — if you already have a Mac II that you're using for music, it's not a heavy investment at all.

One note about that hardware: the Audiomedia system costs about a third as much as the Sound Tools system, and provides fidelity that is very nearly as good. However, the Audiomedia software does not allow Deck files to be transferred to and from samplers, whereas the Sound Designer II software (which comes with Sound Tools) does.

The Sound Designer II software can only work in the presence of a Sound Accelerator card (part of the Sound Tools package). But if you would like to use Deck files with a sampler and don't want to fork out for the more expensive hardware, you can do so with Digidesign's Sound Designer SK or Passport Designs' Alchemy programs. The process might not be quite as fast or elegant as with Sound Designer II, but the results should be just as good.

Digidesign have made it clear that Deck is just the beginning for them in terms of low-cost multitrack hard disk recording. A new version of the Sound Tools hardware called Pro I/O, featuring balanced inputs and outputs, Apogee filters, and true SMPTE sync, has been announced for later this year, and a true 4-channel (in and out) version of the hardware and software, tentatively called Pro Deck, will be available early next year.

The company is not afraid to announce these products because they have instigated an unusually generous upgrade policy on both software and hardware, and so they are hoping early users will not feel excessively penalised for their pioneering spirits. They shouldn't worry: Deck is a highly functional and useful program in its current state, and it is also a tantalising signpost for things to come.

FURTHER INFORMATION

£399 inc VAT.

Sound Technology plc, (Contact Details).