Sunday, January 27, 2008

IMAX 3D vs. broadband

Watching a concert film on IMAX 3D is an interesting experience. You get a much better view, for a stadium show, than anyone actually in the house -- sort of like you're somewhere close to the stage and really tall and able to float up level with or above the performers at random intervals. The sound is great, and perfectly synchronized, unlike sitting up in the nosebleeds with a slight-but-noticeable lag between the big screen and the speakers. You can hear the virtual crowd roar around you, even if the actual crowd around you is quiet.

The screen is big enough and close enough that you can't quite take it all in at once. If something darts forward off to one side, you have to turn (slightly) to see it in focus. You don't have to turn as far as you would in real life, another slight but unavoidable disconnect between being fully immersed and sitting in a theater with a huge screen and great speakers.

Note to directors: The 3-D cameras love the drum kit -- all those cylinders poised at various angles -- but don't overdo it. There's also another slight disconnect here. The drumsticks strobe noticeably since even IMAX is still 24 frames per second.

Now for the interesting question: How many bits?

IMAX film has a resolution of approximately 10,000 by 7,000. Assuming 32-bit color, 24 frames per second and 2 cameras, that comes out to about 13 gigabytes per second, uncompressed. There's ample room for compression, particularly in 3D since the two images are largely identical, but you're still talking on the order of a gigabyte per second. Picture throwing two blu-ray DVDs into the maw of the beast every minute and you're in the ballpark.

Leaving aside the small matter of installing an IMAX home theater, could you at least stream the bits into your house? If you happen to have 10-gigabit ethernet or better coming in, you're good to go. 75-year-old Sigbritt Löthberg of Karlstad, Sweden does, thanks to her son, Peter (see here for slightly more details). I don't, and you probably don't, either.

On the other hand, gigabytes are getting cheaper every day. Last I looked, hard drives were running around $0.30/GB. A 90-minute movie would require about 5TB of disk (5400GB at 1GB/second), over $1000 retail. That's probably viable for theaters now -- IMAX film reels are massive -- but not quite ready for home use.

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