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The audio configuration at the Melbourne Planetarium features a 6-track multi-track played through 6 discrete speakers. There is no spatial encoding involved as the multi-track (a DA-88) is linked directly to a set of amplifiers and connected speakers.
The spatial lay-out is an unusual one that simulates an expanded screen above, in front of and below the listener as they lay in a recliner seat at 140° recline.
A timecode sub-track of the DA-88 serves as the master for the major components of the Melbourne Planetarium's audiovisual infrastructure at the time of this commission:
1. 3 Betacam video decks (each with their own projection, 2 of which are on moveable skews)
2. the DigiStar programme (which generates wire-frame simulations of mapped data from a database of star constellations and their position within the solar system, and projects these computer animations onto the 180¼ dome screen)
3. a custom synchronizing programme called Spice (for sending action lists and sequences to control and trigger movements of the video projector skews as well as the banks ofover 40 35mmslide projectors)This system has since been replaced by a full-dome projection – SkyScan Digital Sky – promoted as a seamless visualization system for 180° set-ups, though lacking in the hybrid charm of the earlier system.
Producing the sound design for a Planetarium show is not as straightforward as working on a film. Firstly, there is no'single screen' to work to. Production involves working with 4 separate time-coded tapes for synchronization:
1. an 'A-Roll' of video
2. a 'B-Roll' of video
3. a flat-screen output from the Digistar system, representing the dome animated dome projection on a 360° circular disc
4. a low-light fish-eye lense vidoe shot inside the Planetarium showing the slides and video being projected onto the dome (the light does not pick up the DigiStar projection)Prior to receiving these 4 tapes, extensive planning is done while the show is being developed and edited. In the case of Launch Pad a demo voice-track was recorded to provide an initial timing guide to produce an animatic. This was then checked for sound effcts timing to ensure that voice narration was separated or spaced away from any major sonic events (explosions, etc.). The animatic was then locked-off and an EDL of trigger events for Spice, markers for the voice track and time-code positions for sound events was generated. The actors were then recorded in a studio and then repositioned over the rough vocal guide-track of the animatic. Once these voices were in place, the rest of the sound design and score could be positioned.
Working in such an open-ended format as a Planetarium show demonstrates the fluidity that exist between pre-production and post-production in sound designing and film scoring. because there is no actual 'shoot' pre- and post- are merged, and in the process one can see the value of preparing simulataneous to the creation, production and placement of the mulitple image tracks.
Spatialization mixing is largely intuitive within such a system. All sound design for launch Pad was done on an ASR10 workstation with an Output Expander. All immersive and dynamic spatial events and gestures are handled through MIDI editing, using extensive controller data to generate precisely articulated movement. Whereas shifting audio data through multiple speakers mainly relies on panning and volume, MIDI manipulation affords an expanded palette of possibilites (pitch, filter, LFOs, gates, envelopes, FX algorithms, etc.). The mix is checked at a number of stages in the actual Planetarium. Notes are taken on how the sounds are sitting in the space, and then the MIDI data is edited back at my studio.
The music score is also produced on an ASR10. All instrumentation is complexly routed through MIDI manipultion throughout the surround soundfield. By working with both sound and music within the one system, great flexibility is available in the mixing and merging of the two. No clashes occur as there is always a way to alter or modiffy micro- or internal details of sound or music data at any one point.
The final mix is mastered with light compression (mainly for voices) onto a DA-88 tape. The output level of the tape is controlled by the Spice programme.
Complete contents of this page © Philip Brophy