MIX FIELD TEST: Solid State Logic Altimix
Digital Post Production System

Reviewed by Mel Lambert

SSL's new Altimix digital post production system is, without doubt, a product that will radically streamline the way in which audio materials can be handled during film and video post production. Just as ScreenSound, Scenaria and OmniMix redefined the paradigm of how sounds could be edited, mixed, processed and then exchanged between subsystems in an all-digital post facility, so Altimix is destined to literally revolutionize the process, and make fully integrated post production a practical reality. I would go so far as saying that Altimix is has been designed for the post production environment of 15 minutes into our inevitable future, where the traditional barriers between film, video and audio will have all but disappeared.

   The key to Altimix' power - and that of its companion "A-Series Systems," including Axiom and Aysis mixing console/recorders - is the firm's powerful DiskTrack and Hub Router Resource Manager with a wide range of I/O options. More than just a hard-disk recorder/player that provides instant access to multitrack audio material (up to 96 hours), DiskTrack offers the ability to share storage and processing resources between component systems. In other words, in combination with a Hub Router, DiskTrack provides a centralized resource server and project manager for Altimix, Axiom and Aysis, as well as the auxiliary Audio Preparation Station. (Via the Hub Router and DiskTrack APS provides access to up to 24 tracks from the available 128-track central pool.)

   All interconnection is achieved via SSL's proprietary Hi-Way and FreeWay serial digital technology, allowing simple and fast system installation. System commands are sent from the control surface via a combination of Ethernet and high-speed digital links to the audio and video processors, where control information is processed and applied to the data provided from DiskTrack. Because system data is centralized in the DiskTrack hub, all project information can easily be archived in single step. All audio, automation data, routing, edit information and file notes are stored within Altimix as a single project file that can be accessed later date, or transferred to Axiom or Aysis systems. Concurrent backup/restore enables projects to be backed up or restored off-line, simultaneous with a new project, thereby maximizing the availability of studio facilities.

In a typical scenario (pardon the pun), multiple Altimix-equipped suites might be used within pre-lay, conform and edit suites to develop component elements for a complex film or video project, while large-format Axiom- and/or Aysis-equipped mix-to-picture rooms prepare multi-format stems and finals. (Contrast this with Scenario/OmniMix systems, which utilize SoundNET, an intelligent SCSI-based router to switch real-time access to stored audio material, but which cannot provide the concurrent access offered by DiskTrack, nor sophisticated multi-function routing.)

   Which does not mean that Altimix cannot be considered as a stand-alone product; as I discovered during my extensive hands-on sessions in Hollywood and Begbroke, England, Altimix is one of the most powerful, feature-rich post systems that I have ever experienced. Altimix is based on a compact, user-friendly assignable control surface that offers integrated video and audio mixing functionality. A shared multi-disk record/replay array enables instant access to video and audio material, and ensures fully synchronous operation across both domains. Laid out in much the same basic topology as the previous Scenaria and OmniMix systems, but with additional I/O capacity, the new Altimix features 24 servo-driven channel faders in a powerful channel/group architecture; as would be expected, full dynamic automation is provided for all mixing, editing, processing and switching functions.

   Axiom will accommodate a total of 48 simultaneous mixing channels with 16 controlling groups, and up to 48-track/20-bit recording/editing, expandable to 128 channels of disk recording with multi-user partitioning. Via a conventional set-up page, analog and/or input sources are allocated a channel path, and assigned to a specific output port. Master sampling rate is 48 kHz; sample-rate converters are available for digital sources running at other frequencies. Altimix will also import sound files in a number of formats, including OMFI, .WAV, AIFF, Lightworks and Digidesign SDII.

   Altimix' array of 24 on-surface channels can be laid out in a variety of ways, dependent upon the intended application(s). For example, the system I used in Begbroke comprised two banks of eight input channels to the left and eight groupers to the right, with a central controller section between them. But, since Axiom is based on a modular construction, inputs and grouper bays can be physically swapped around as necessary. Accessing the inputs is achieved via three layers that can be assigned to the physical faders in any layout the user chooses, with two groups layers being accessed in the same way.

Assignable System Controls for EQ, Dynamics, Routing and Effects
Signal processing is accessed via a bank of dedicated controls above each input bank; at the top are shaft encoders for a four-band parametric EQ section, with accompanying graphics display, below which is a multi-function dynamics section with compression, limiting, gating, etc., (also with a graphics window of input/output transfer function), and a routing assignment panel for accessing sources and up to 32 main mix buss destinations.

   Selecting one or more mix busses also assigns the appropriate surround-sound pan laws to a pair of rotary controls that handle, dependent upon the status of companion switches, X- (L/R) and Y-axis (F/B) panning. When panned to the rear, operation of left/right panning moves the signal between left-surround and right-surround speakers. As an alternative to the individual channel pan controls, a screen-based panning display can be controlled directly using the pen and tablet. Screen panning can also be operated in a very handy key-frame mode, known as Motion Tracking, which allows panning to be interpolated at sample rate between selected timecode key points.

   The EQ section features four bands that can each be identically configured as a High & Low Filter, High & Low Shelf, Notch and Parametric. While each band is capable of accessing the full audio range, this can usefully be tailored to definable user limits and options (using an editable setup text file). All EQ settings can be dynamically automated and snapshot memorized. A library of 64 user-selectable/savable EQ presets is also provided. And, yes, the all-digital EQ sounds great!

The dedicated Dynamics Processor per channel offers limiting, compression, expansion and gating in three adjustable level bands allocated as Lower Band: Gate only; Middle Band: Compression, Limiting or Expansion; Upper Band: Compression, Limiting or Expansion. All three bands are simultaneously active, allowing the user to insert a gate, compressor and limiter on the same channel. The Dynamics Processor is fully automated and can be reset using snapshots. A Delay Control selects a feed-forward option to delay the main signal path by up to 20 mS, to enable large amounts of dynamics processing without overshoots or distortion. Gain make-up can be either automatic set manually. Dynamics settings can also be copied from channel to channel, and/or saved to a preset library.

Centralized Monitoring and Master Controls
The Central Section houses various monitoring and master controls, in addition to a QWERTY keyboard, pen/tablet, plus motion controller and scrub wheel for DiskTrack and/or external audio/video transports. Machine control is via four serial control ports that can follow Sony 9-pin, VPR-3 or Sony Slave protocols. The Group Controller section also houses an assignable panel that implements changes for insert I/Os and internal special effects, which include multi-channel reverb and delay processing; a library of pre-configured on-board and outboard processing functions can be called up on a channel-by-channel or group basis. Usefully, a bank of automated send/receive level controls help reduce the amount of gymnastics that the user needs to perform while setting up external effects sends via a sophisticated insert matrix. And, because each insert returns is multi-channel in function, a single "channel" can be used to provide a stereo return, or maybe an eight-channel pre-dub input, if that is your requirement. Finally, a 21-inch color monitor above the master section displays a variety of inter-related screens for system setup, waveform editing, mixing and other functions.

   One of four video streams can be user-positioned and resized to appear anywhere within the monitor; of course, a dedicated NTSC video feed supply separate color monitor(s) during the session. Why four video streams via DiskTrack, which in addition to providing up to 48 tracks/72 hours of audio storage, holds up to two hours (expandable to five) of non-linear video ? I wondered that as well. A major new feature of Altimix is its ability to manipulate video in addition to audio. The four vertical reels to the left of the editing options can be used for different projects, or different aspect- -  ADR/Foley and dialog, for example - of a current project. Also, if there are last-minute picture changes (and when aren't there?), new or replacement sections can be recorded into the system and then merged with existing material using simple cut and past of audio and video streams. Video clips can be loaded in Absolute Mode (their recorded position), at a specific timecode, or to start at the current Playhead position.

   Access to any part of the project simply involves stabbing the graphics pen at the section of video to be recalled to the Now Line. Modifying a video stream on Altimix is simple, using operations that are the same as for editing audio reels (copy, move, shift, etc.), the only exception being that any crossfade function is ignored. (To avoid straining the internal DSP resources, all video transitions are butt edits to frame boundaries- but, there again, Altimix is an audio system.) Placing the audio reels within a video edit group allows them to be edited together with the video, a function that operates in a similar way to the audio edit group except that a video edit action is taken as the master guide for editing commands. Simplicity personified.

   Each set of servo-fader panels offers Solo and Cut switches per channel, plus record enable buttons for DiskTrack and Access buttons for assignable EQ, dynamic and related functions. Each Altimix mix channel features access to eight Auxiliary buses that can be configured as mono or stereo sends in any combination. Control of each send is assigned to either the channel faders or pan controls.

   Each channel is provided with access to one of 16 pre/post fader insert presets which, in turn, are accessed via a routing matrix. Channel inserts offer a powerful return structure that allows a single channel fader to return a multi-channel signal according to the return channel's stem bus assignment. If panning is incorporated with this assignment, then pan controls will effect the balance of the signals to the busses. The fader, however, will always control gain for the return.

   A pool of 48 internal effects DSPs within Altimix are associated with the insert return functionality. By routing an insert return from one or more effects processors, multi-channel effects sections can be configured, including configurations beyond stereo to 7.1 or eight channels.

   All in all, the ergonomics of the Altimix control surface is a revelation; it's a shame that other workstations could not be laid in such a clean, uncluttered manner, with dedicated controls for the regular functions- and ones that are large enough to grasp easily- with assignable access to less-necessary functions.

Flexible Input/Output Routing and Monitoring
In terms of I/O functions, Altimix offers many powerful options. The 32 primary busses are configured as an array of four stems with eight-bus component program mixes, linked to a 32-by-8 channel assignable monitor matrix. Also provided is inter-format monitoring with external insertion of encode/decode matrix units. As might be expected, users can import Edit    Decision Lists in a variety of formats for project reconfirmation from external EDLs. And for enhanced compatibility with existing SSL-equipped suites, Altimix will import desk files from ScreenSound, Scenaria and OmniMix via a dedicated SCSI port that connects to external hard drives.

   As with other members of the SSL A-Series products, DiskTrack's integral Hub Router provides numerous input/output format options. Analog Remote Input/Output units (A-RIOs) provide up to 48 analog line-level I/O (16/20-bit options); outboard microphone pre-amps can also be remote controlled. Each of the A-RIO's 12 inputs feature a selectable limiter and switchable 20/100 Hz highpass Filter. Digital Remote Input/Output units (D-RIOs, as if you haven't guessed) feature combinations of up to 96 synchronous 48 kHz AES/EBU-format inputs and outputs, or up to 48 asynchronous AES/EBU-format sample-rate converting inputs and outputs. In addition, a multichannel SDIF2-compatible interface provides digital connection to a variety of multitrack tape machines, and similar systems.

   Altimix' Monitoring Section is configured in two main parts. Monitor Insert Sent is fabricated from a matrix assignment, as with the Program Mix. (If you select to monitor Program, for example, Altimix assumes the settings- and bus sources- of the program matrix.) Selecting External Monitoring allows a set of 16 programmable keys to re-configure both external and bus sources to the matrix, and hence to the Monitor Insert Send. A second set of programmable keys allow an external source to be switched between associated Bus and Tape signals, for mimicking the operation of familiar PEC/DIR switching.

Having configured the monitor send matrix, signals are directed to the DiskTrack routing and hence to matrix-encoding devices. The monitor signal is then fed through a further 8x8 fold-down matrix for monitoring in a variety of programmable monitor formats, to switch the same monitor signal between Mono, Stereo, LCRS surround, Lt Rt, and LCRLsRs, for example.

Advanced Non-Linear Editing Functions
Space prevents me from providing more than a brief overview of Altimix' powerful recording and editing functions which, to say the least, are extensive. Stand-out features include automatic record take management, with 50 levels of undo; a multi-level take editor; plus 48-track drop-ins with instantaneous playback monitoring and user-programmable advance record. Useful new editing commands include real-time clip auditioning and spotting; clip gain profiling; and a multi-channel feature set that dynamically links automation data to audio clips for repeatability through multiple editorial changes.

It is amazing how soon you get used to the ability to edit audio tracks with high-speed integrated- and editable- video. Altimix' scrolling waveform displays are very easy to work with, and move across the screen with no tearing nor shimmer. The integration of a fully automated 48-channel digital console may be overkill for editorial suites, but really comes into its own for complex mix-to-picture sessions, where the ability to rapidly touch up and/or edit a track in real-time is soon taken for granted. The four- band parametric EQ is very powerful, as is the three-band dynamics processing provided on every channel. Built-in multi-channel reverbs also enable tracks to be processed during a mix, and then re-processed for different applications.

   The Altimix control surface gives every appearance of having been designed to provide an intuitive workplace for both editing and mixing. The majority of the editing functions are controlled from the pen, keyboard and motion control panels with dedicated EQ, dynamics and fader panels controlling channel signals.

Recording audio directly to disk is as simple as selecting a disk source for a channel, and then hitting the record key on that channel. The currently assigned source is displayed on the fader scribble strip; accessing the source routing panel sets up routing for the record source assigned to this disk track. (A Range Setting function allows an number of channels to be set up simultaneously.) Drop-ins can be achieved using the familiar combination of transport controls, each pass being stored independently as a separate take that can be edited to select a master take for each channel. Up to 48 tracks can be recorded simultaneously, if necessary.

   During waveform editing, Altimix provides the user with a number of Personable Editing Tools (PET) that dramatically speed up the process via a number of interesting new techniques. By recognizing various pen movements, shortcuts are offered for various editing functions. Pressing a switch on the side of the graphics pen and performing the required stroke- for example, a downward movement- will activate a Delete Function, while a "C-shaped" movement might activate Copy Mode. In this way, as single stroke of the pen simultaneously selects the function and clip. Similar keyboard shortcuts are also available.

   On-screen icons located to the right of the edit display screen represent the tracks to be edited; audio can be fetched to these reels from the main File menu. Usefully, a Listen function can be used to audition, select and pre-edit the desired clips from disk without leaving the edit page. A clip placed on a reel is represented in blue; depending on the zoom scale, red (second) or light blue (minute) ticks along the sides of these clips allow easy location of the current and relative cue locations.

   The Desk Reel function allows a minimum of two and a maximum of 24 reels to be viewed on the screen. During zoom in/out- to view between one second of audio per reel, and more than 30 minutes- a white scroll bar in the lower left of the editing screen adjusts to provide access to all of the 48 editing reels at this selected resolution. Edit point can be marked from the Waveform display, or by scrubbing audio. Multiple edit groups allow any of the 48 editing reels to be grouped together, moved and/or edited together. You really have to work hard to get lost on Altimix!

   Clips can also be named individually, with an abbreviated version of the name being displayed at its head of a clip. The Events list also displays a variety of timecode events, including Clip Start and End points, that can be used buy the transport controls to directly locate to the next/previous event. A useful QuickClips function serves as a scrapbook for up to 12 segments. To create an ambiance loop, for example, an original ambiance clip might be repeated a few times, joined each time to itself with a crossfade. The result can be accessed several times in a production via the QuickClips area, as one composite clip; it is also possible to recover the various elements of the original loop complete with discrete crossfades.

Multi-Channel Automation Modes
In terms of system automation modes, each group of controls- faders, EQ, panning, etc.- is treated within Altimix as a separate entity. All of which means that fader information can be updated, while the EQ and Dynamics, for example, are set in safe-protected mode. Available modes include real-time and clip-based automation, including Protect, Static, Overwrite, Rollback, Clip Fill, Clip End, Cycle Fill and Cycle End. Particularly useful for updating fader automation is "Snap with Autoglide," which starts by writing updates as soon as the fader is touched; when the fader is released, it snaps back to the previous mix over a defined Autoglide period (up to 10 seconds).

   Each channel features dedicated Protect and Inhibit buttons. The former prevents new control changes from being written as automation data while the latter prevents automation replaying on a selected channel. Having written some moves, a mix pass is confirmed by stopping and using a rollback command.

   Usefully, the past six automation passes are held in memory; any one can be held indefinitely as a reference mix. The current mix can be stored permanently as part of a Project by hitting a dedicated Save Project button. In addition to dynamic automation, Altimix also features snapshot reset. A total of 40 snapshot memories can be recalled, globally or selectively, at a later date. Snapshots will reset all automated controls: Faders (channel and group faders), Panning, EQ, Dynamics, Gain trims, FX processing and Auxiliary Sends. Any channel that is Inhibited will be unaffected by a snapshot reset.

   A comprehensive Project Management function saves, as individual elements, all the major components of a session, including editing, mixing, monitoring and routing. Data is consolidated on DiskTrack, and can be backed up to floppy, MO or Exabyte media with other system data.

In Nutshell: A totally Integrated Digital Audio Production Environment
In many ways, Altimix is much more than just another digital-audio post production tool. The system's comprehensive networking capabilities, for example, have been designed specifically to maximize facility resources and offer the ability to fabricate a fully integrated all-digital post/broadcast production environment. SSL's design approach integrates all the components for audio post into a single user-friendly surround-sound system that offers unprecedented connectivity. Altimix provides instant access to stored audio and video though a shared multi-disk array, as well as an ergonomically-designed console surface with 24 assignable motorized faders laid out with a flexible channel/group architecture. Dedicated, user-friendly control panels are provided for all automated DSP, routing and switching functions dramatically reduce the learning curve.

   All in all, Altimix is a hard system to fault. A new level of integrating audio with random access video allows the re-arrangement of both sound and picture within the one system, thus making it possible to audition large-scale project changes even during final mixdown. It is no exaggeration to say that Altimix is destined to provide new levels of power and flexibility to creative sound designer around the world.

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