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Digidesign Pro Tools TDM 5.1

February 1, 2002
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Surround sound is everywhere. Once the exclusive bastion of film, multichannel audio has spread rapidly into the worlds of music, games, and broadcast. The advent of affordable home theater, DTS, DVD-Audio, and multichannel game consoles ensures that every recording musician and audio professional will become involved in surround sound in some capacity.

Digidesign brings the Pro Tools system squarely into the multichannel age with the appropriately numbered version 5.1. The new version includes a solid set of new features as well as improved MIDI implementation, file management, user interface, and plug-ins.

NEW PATHS

The first step Digidesign took toward creating a multichannel environment was to completely change how Pro Tools TDM 5.1 interacts with the outside world. The new I/O setup window (see Fig. 1) gives you signal-routing flexibility by allowing you to easily group, name, and configure all inputs, outputs, inserts, and buses.

The path is the organizing layer between Pro Tools TDM 5.1 tracks and the hardware I/O. Each path has from one (mono) to eight (in a 7.1 surround system) channels. Once a path is selected, the channels for that path appear on a grid that displays the hardware I/O units connected to the system. Each channel is configured by dragging its icon (left, right, center, and so on) to whichever output is desired. Furthermore, each path can have a number of subpaths, which contain a subset of the number of channels in the main path.

For example, take a 5.1 surround output path with six channels — left, right, center, subwoofer, left surround, and right surround — configured to the first of a pair of 888 I/O output tracks 1 through 6, respectively. (They can be configured to whatever outputs you want, however, even across different I/O units). Under that surround master path, stereo, LCR, and mono sub-paths that also use the same outputs can be created. That means the stereo subpath would send left-channel information to output 1 and right-channel information to output 2, just as the surround master path does.

Paths can be defined for inputs, outputs, inserts, buses, and the SampleCell TDM sampler card. The entire I/O setup can then be exported for use in other sessions. All I/O setups can be selected in the Create Session window or imported into other sessions. Getting the hang of setting up paths can take a while, but once you become comfortable with it, it's a great way to work.

ON TRACK

The reason for having a flexible signal-routing structure is clear when you look at tracks. The limitation of mono-only audio tracks in Pro Tools is no longer an issue. Tracks can now have one to eight channels, just like paths. The channels in a track are recorded or edited as a unit, and the corresponding regions are stored in the region bin hierarchically, under the master region name (see Fig. 2). Recording to a 5.1 track called “Strings” would result in a region called Strings_01 and a series of subregions called Strings_01.L, Strings_01.R, Strings_01.C, and so forth.

Multichannel tracks have separate software meters for each channel in the Edit and Mix windows. Any edits or manipulations of a multichannel region affect all channels. Multichannel tracks need to be connected to hardware ins through paths or subpaths with the same number of channels. To record to a 5.1 track, you must create a 5.1 input path.

Output paths work the same, although multichannel tracks can be routed to mono output paths. Mono tracks have the most flexibility: they can be assigned to output paths of any number of channels. A really cool feature is the ability to assign each track to multiple output paths at the same time. That means that, with enough hardware outs, you could work simultaneously on a 5.1 mix, a quad LCRS mix for Dolby Pro Logic, and a stereo reduction from the same session. However, keep in mind that the surround capabilities of Pro Tools 5.1 are available only on 24 Mix systems and above.

AROUND THE ROOM

Once you have defined the paths and track assignments, you can begin mixing in surround. Every mono track that is assigned to an output path of four or more channels will have its panners replaced by a small surround-grid icon that shows the relative position of the track in the surround field. Stereo tracks have two surround grids next to each other. Tracks with more than two channels are simply bused directly to their assigned output path, with no pan control. The SurroundScope plug-in does a nice job of showing the energy distribution and phase coherency of a multichannel track on meters as well as a surround view.

You access the Surround pop-up window for each track by clicking on the output asterisk in the track's mix view (see Fig. 3). That window is the heart of surround mixing in Pro Tools. It depicts the position of the sound as a green dot on a grid representing the surround matrix. Speaker icons, representing the location of the physical speakers in the matrix, appear around the edge of the grid — an LCRS matrix has three speaker icons across the front and a single speaker in the center of the rear; a 7.1 matrix shows five speakers across the front and two in the rear.

In addition, the window contains a separate fader for the low-frequency enhancement (LFE; the “.1”) track. Moving the dot on the grid positions the track in the listening space. All of the features can be automated; to move the sound over time, you must arm the automation and then drag the dot around.

You can also move the position of the audio along a straight line through the matrix by using the position controls. The Front and Rear knobs control left and right positions in the front and rear, and the F/R knob controls the position of the audio along that continuum. That lets you move the position of a sound using one knob.

The Center % knob controls how much of the audio appears in the physical center channel. In film mixes, center is often reserved for dialog to enhance intelligibility, so keeping sound effects out of the center as they pan from left to right is crucial.

The Divergence portion of the Surround pop-up window refers to a track's width within the surround matrix. Any track can be a single sharply focused point in the audio field, or the track can be widened to encompass a broader location. Divergence is handled just like position: Front and Rear knobs represent the width of the sound as it emanates from the front or rear, and an F/R knob represents the ratio of front-to-rear energy. The ratio is displayed graphically as a blue polygon within the surround grid. The Divergence controls can be automated, too.

Yet another critical element in surround applications is the concept of bass management; the redirection of all low-frequency information below a specified crossover point into the subwoofer channel. Because bass frequencies are far less directional than higher frequencies, keeping unnecessary low frequencies out of the speakers allows them to operate more efficiently. My only gripe with the surround functionality of Pro Tools TDM 5.1 is that it has no integrated bass-management system. The Woofie plug-in ($249) from Kind of Loud Technologies will handle the problem, but I would prefer a solution integrated into the Pro Tools Surround window.

MORE MIDI FRIENDLY

Although its MIDI implementation is no match for advanced sequencers such as Emagic's Logic Audio or Mark of the Unicorn's (MOTU's) Digital Performer, Pro Tools TDM 5.1 boasts some new MIDI features that make its sequencing capabilities more usable. The most important is the MIDI Event List (see Fig. 4), which is interactive with the Edit window. Events selected or changed in one are immediately updated in the other. Notes and controllers can be inserted or edited easily, and a view filter can be applied to show specified event types.

The Pro Tools MIDI implementation has other interesting additions. Now, you can patch a MIDI controller through Pro Tools TDM 5.1 to a MIDI module without being in Record mode; multiple MIDI data streams can be recorded simultaneously, and each stream can be assigned its own track; each MIDI track can be assigned a sample offset to make up for sluggish attacks or latency issues in the system; and on the Macintosh platform, synthesizer patch names are available through Open Music System (OMS) name services.

PLUG IN TO SURROUND

One of Pro Tools' great strengths is its TDM-based plug-in architecture. Digidesign improved the architecture to accommodate multichannel audio. Multichannel tracks can use new multichannel plug-ins that are designed for the new system as well as multiple instances of standard mono plug-ins (one per channel). You can adjust each instantiation separately or link them together to one set of controls.

Another long-awaited improvement is the ability to have multiple plug-in windows open at once. Each plug-in window can now stay up until it is dismissed or replaced by a new plug-in. You can drag and drop instances of a plug-in to different positions on the same track or move them to various tracks. They can also be Option-dragged to other tracks, which creates a copy with the same settings as the original plug-in. Each small graphical user interface (GUI) improvement enhances the mixing process dramatically.

However, there's no free lunch in multichannel audio: a plug-in's 6-channel version requires far more digital signal processing (DSP) than the mono version. A substantial 5.1 mixdown can quickly bring the DSP resources of a powerful 24 Mixplus system to its knees. Digidesign attacked that problem from three directions: by making Real Time AudioSuite (RTAS) plug-ins available in TDM sessions, by creating a new DSP chip-sharing technology called MultiShell II, and by adding one more Mix Farm card to the standard system.

The RTAS system is the host-based plug-in format used with the Pro Tools LE/Digi001 system. In a Pro Tools TDM system with version 5.1, RTAS and TDM plug-ins can be used in the same track, but the RTAS plugs have to come first in the chain. Using RTAS plug-ins takes a load off of the DSP cards but increases the load on the CPU and adds to system latency.

MultiShell II lets multiple compatible plug-ins share time on the same DSP chip. Waves began that idea with its WaveShell-DAE system, in which all Waves plug-ins shared the same chips. Now Digidesign has created a standard that all manufacturers can share.

Finally, Digidesign is now pushing its new flagship Pro Tools Mix3 package, which consists of two Mix Farm cards and one Mix Core card. At a list price of $11,995 for just the DSP cards — I/O is not included — the system is extremely powerful but brutal on the wallet.

EDITING IMPROVEMENTS

Digidesign made a number of small but useful improvements to the user interface and editing features. On the Macintosh side, Digidesign improved the use of dialog boxes by using Apple's standardized GUI. That includes navigation buttons, in the upper-right corner of the box, that allow you to set favorite folders. The Create New Session dialog box lets you specify the I/O settings (with defaults for stereo, a variety of 5.1 formats, and your own I/O routings), the native audio file type (WAV, AIFF, or Sound Designer II), as well as bit depth and sample rate. However, it always defaults to 24 bit, 44.1 kHz rather than the settings of the last session you created.

The nifty new Universe pop-up window provides a graphic overview of the entire session, which allows you to navigate a long session with just one click. The E key is now a toggle that enlarges and shrinks the area near the edit bar, and the Hyphen key toggles between Waveform and Volume view. The Tab-to-Transient option uses the Tab key to move the edit bar to the next transient in a track. That is great for dialog editing, percussive sounds, and spacious tracks, but not as useful for dense tracks. An adjustable threshold preference would really help dial in the usability. Version 5.1.1 (which will be available by the time you read this) includes GUI improvements in the area of showing or hiding and sorting tracks as well as a useful Single Zoom mode, which jumps back to whatever editing tool was last used after a single use of the Magnifier tool.

WHAT'S IN A NAME

Previously, one had to be careful when referencing audio files that were outside a session's audio-files folder. Moving a file to another hard drive or directory caused Pro Tools to lose track of its location, creating major headaches. Additional confusion resulted from Pro Tools's default naming convention: a hard drive with many sessions can end up with dozens of audio files named Audio 1_01.

Digidesign has addressed those issues by adding a universal identifier (UID) to each file. The internal serial number is used to track the files, making it easier for Pro Tools TDM 5.1 to find them if they move to other folders or volumes and letting you discriminate between files of the same name. Audio files that can't be found at all are considered to be offline but still part of the session.

Blue ghost regions appear in the Edit window, where the online data used to be. You can still edit or delete those regions, but you won't hear the results. The names of the missing files appear in italics in the region bin and are automatically relinked later when the files are made available. In addition, the naming convention for fade files has changed from a numerical sequence (for example, Fade 01, Fade 02) to long streams of random letters (Fade abYBBQgHGbZHM4).

ON THE BEAT

Beat Detective (see Fig. 5) is a spiffy new tool used to create tempo maps and tighten up human performances. You can select a region of audio (a percussive element, such as a kick drum, works best) and ask Beat Detective to analyze it to a resolution of bars, beats, or subbeats. You can help Beat Detective out by telling it what the starting and ending bar or beat value of the region should be and by adjusting the analysis sensitivity. Beat Detective will then create a tempo map and adjust the bars and beats accordingly.

That feature is wonderful for aligning the Pro Tools TDM 5.1 counter system to a human performance after the fact. In addition, you can separate the audio into regions at the beat locations analyzed and then conform the data to line up at a different tempo, effectively quantizing the audio performance. Making that sound good in a real-world situation takes some effort, but the ability to tighten the timing or change the tempo of a performance is powerful. A smoothing facility is included to crossfade through gaps that might stick out in the audio.

BUT WAIT, THERE'S MORE

The Strip Silence feature has been greatly improved. It's used to remove silent or quiet areas of audio from a track and separate the remaining material into individual regions. Strip Silence has always been a rather difficult beast to tame. Typically it involved repeated experiments with the Threshold setting to find a good fit. Now, before you commit to processing the file, Strip Silence shows you graphically which areas will stay and which will be deleted as you operate the Threshold slider.

Disk allocation, or the method of determining where Pro Tools stores audio data for different tracks, is much more flexible now. Each track has its own path assignment, so you can assign each track to record to a different folder, if you desire. You can also set the Root Media folder (previously the Audio Files folder in the same directory as the session file) to whatever you want. In general, that idea is flexible, albeit a bit dangerous: as files spread out, keeping track of their locations can become difficult.

However, that opens the door to new paradigms of distributed media processing. For example, take a network of people working on a piece of music or a film simultaneously. If the network (local or Internet) were fast enough, dialog, music, and effects could all be recorded onto a centralized server. That would allow files to be distributed easily, and creating backups would be less of a headache.

Additional improvements around the edges of the program will appeal to various types of users: 16 levels of undo, an Auto Save function, track-import ability, and OMF import and export functionality using DigiTranslator 2.0 are available. If you use Avid's video boards with your Pro Tools system, you can have multiple digital-video segments in the video track. In addition, you can record video directly into Pro Tools TDM 5.1 rather than capturing it separately and then importing it. Unfortunately, those video features don't work with the third-party boards from Aurora and Miro, which are frequently used with Pro Tools.

Pro Tools TDM 5.1 also supports Sony 9-pin VTR emulation through a direct connection to the serial port. That makes it easy to control the system with a remote transport mechanism such as a Microlynx.

CRASHPROOF

The marketing department often avoids mentioning one of the most important improvements an upgrade can offer: namely, fewer crashes. That is certainly an improvement on Pro Tools TDM 5.1, the most stable version of the program I've ever used.

Daily system crashes were a fact of life for me up through version 5.0.1. But I had Pro Tools TDM 5.1 running on multiple systems 16 hours a day for three weeks while recording Foley for a film, and it never crashed. That is the type of bread-and-butter software that can be relied upon in a serious production environment.

BETTER THAN EVER

It's hard not to rave about Pro Tools TDM 5.1. The software is mature, robust, stable, and flexible. Not surprisingly, Pro Tools remains the system of choice for a large percentage of the professional-audio industry.

The new surround-mixing capabilities are worth the price of admission alone. However, the greatly improved I/O routing, system stability, and MIDI features make the upgrade from 5.0 to 5.1 a no-brainer for any current Pro Tools user.


Nick Peck owns Perceptive Sound Design, an audio post facility for film and games. He also plays keyboards in the jam band Ten Ton Chicken.

PRODUCT SUMMARY

Digidesign
Pro Tools 5.1 (Mac/Win)
digital audio workstation
Pro Tools/24 Mix w/Pro Tools TDM 5.1
$7,995
Upgrade from v. 5.0.1 or earlier
$295

FEATURES 4.5
EASE OF USE 4.5
DOCUMENTATION 4.0
VALUE 3.5

RATING PRODUCTS FROM 1 TO 5

PROS: Stable. Multichannel capabilities. Widespread third-party support. Large user base throughout pro-audio industry.

CONS: TDM system is expensive.

Manufacturer

Digidesign
tel. (800) 333-2137 or (650) 731-6300
e-mail prodinfo@digidesign.com
Web www.digidesign.com

Pro Tools Specifications
Audio Tracks 64
Virtual Tracks 64
MIDI Tracks 128
Buses 64
Sends Per Track 5
Inserts Per Track 5
Resolution 24-bit; 16-bit
Sequencer Tracks 128 maximum
Sequencer Resolution 960,000 ppqn, synced to internal or MIDI Clock source
Quantization whole note-64th-note triplet

Minimum System Requirements

Pro Tools TDM

MAC: Macintosh 68000; 12 MB RAM; Mac OS 7.0; free modem/printer/USB port

PC: 486 DX2/66; 12 MB RAM; Windows 95/98/ME; free COM (1-4)/USB port

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