The Indian IMAX Experience

November 14th,2001

AES India Section & Indian Documentary Film Producers' Association had a joint technical meeting at the Adlabs IMAX Theatre on 10th November 2001. The program started with an introductory speech by Mr. Manmohan Shetty, Managing Director of ADLABS who has brought the Imax technology to the Indian Subcontinent.

He outlined the policy of his company in introducing the Imax in India. Today, people have hi-tech home theatre systems & expect nothing lessthan spectacular in theatre experiences. Imax is more exciting than traditional theatres.The image size is 10 times larger than the regular 35 mm & 3 times larger than standard 70 mm.

Though he is not entirely satisfied with the occupancy of the Adlabs Imax theatre, he is hopeful that the trend will change in the near future. According to him, the audience is ready for this amazing experience.
The audience, comprising of 30 AES members and about 70 IDPA members, was then treated to an Imax presentation of the famous '' Grand Canyon'' Mr. Govind Nihalani, leading filmmaker and cameraman, then informed the audience about the production techniques of this medium. Mr. Jal Mistry, the man responsible for the good acoustics and the installation of the 12000 watts massive sound system, then proceeded to give the members a presentation about Imax sound requirements. The biggest Imax dome in  the world was a big challenge to acoustically treat and Imax International helped in the design and has been fully satisfied with the final outcome. The 60 metres radius dome has an outer 4-inch thick concrete coating followed by a varying density wool treatment and 2-ft x 2-ft readymade screen planks.
Mr Mistry then showed members the locations of the speakers in   the hall.The six channel system uses Left surround, Left, Centre,  Right, Right surround,and a Top Screen speaker. The top screen  speaker  is crucial because of the huge screen height. Here it  would be logical  to mention SONICS ASSOCIATES of Alabama, USA,   who  are exclusive suppliers for all Imax theatre sound systems which  adhere to strict demands of exemplary performance & service. Unlike other  sound systems that limit the frequency response & dynamic range in the  rear speakers, Imax uses identical full range speakers throughout the theatre. There is no separate boom track and the LF portion of all the speakers feeds the sub woofer assembly after passing through a cut off filter at 100 Hz
Mr. Jal Mistry then took the members to the projection room and explained the unique 'rolling loop' film movement at 24 frames per second, which provides the clear & steady picture. The six-track sound, which comes separately on a CD, is transferred to the integrated disc of the operating computer, which controls every technical function in the theatre-from dimming the lights to syncing the sound with picture. Incidentally there is no timecode on the picture.
POSTPRODUCTION - Imax camera generates large amounts of noise & therefore all audio during production is almost unusable. The narration forms the basic backbone of the soundtrack with Sound Effects, the ambient sounds and the Background music making the entire surround soundscape. There is minimal amount of sync dialogue and all other sound effects are recreated in post. Because of the sheer size of the picture, it becomes almost obligatory for all synced ADR to be sample accurate.

Some thoughts about the Mix - In an Imax theatre, the loudspeakers are far away from the audience and also great distances apart.The distance between the left and the right speaker in a normal film theatre is shorter than the distance between, say the left and the centre speaker in an Imax theatre.

 With such a wide sonic scape the elements do not disturb the narration and thus in the final mix can be pushed up substantially, resulting in a more immersing and satisfying film experience. The music is usually premixed by the music recordist in quad surround. (Left front, right front, left rear and right rear) This means that there is no music in the centre, leaving the channel free for narration. The mixer can then afford to push up the background music score in the final mix. As for panning, very radical mixes can be tried, which can complement the large format image. The dialogues can be placed in any location around the theatre while other elements may have aggressive panning with huge ambient and perspective shiftsforwards and backwards. Imax thus completely encloses  peripheral vision of the audience and surrounds them  with  simultaneous spectacular sound, making the  experience more compelling, more absorbing and more  immersive. The meeting ended with vote of thanks by Mr. Avinash Oak, Chairman, AES   India Section.

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