Film-Tech Forum ARCHIVE: Uses for digital projectors, and are there any Apple Quicktime experts here?

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Topic: Uses for digital projectors, and are there any Apple Quicktime experts here?

Stephen Furley
Film God

Posts: 3059
From: Coulsdon, Croydon, England
Registered: May 2002

posted 08-12-2007 07:22 AM

I've finally managed to do something with the digital projector that I couldn't have done either with film, or with a conventional video projector. This was at an actual show with an audience, not just trying out various things between shows, which I've spent quite a lot of time doing.

Saturday morning children's show, we don't run the adverts and trailers reel with these, but we had a film at the next weeks show, which would appeal to a similar age range to this weeks one, so showing the trailer for that wouldn't seem to be a bad idea. Of course, we don't have a trailer for these films so get onto the Internet via the wireless connection that's available for visitors to the Town Hall/Clocktower, and download a trailer in 1050p format. Quickly make up a suitable caption slide to go before it, total time about ten minutes. Connect laptop into system using DVI connection to Christie Cine IPM 2k for video and Toslink digital optical connection to Dolby DM8 Plus for sound. Laptop has non-standard miniature connectors for both, but I have adapters for both with me in the case. Run trailer on the laptop, then change over to 35mm for the feature. Didn't look quite as good as proper digital cinema content, but not far short of it; it really is surprising how good 1080p HD video can look on a cinema screen, there's no comparison at all to conventional video.

Picture was in H264 format, and sound was six channel AAC, and that's the problem; it comes out of the Quicktime Pro player converted to two channel PCM, which then gets matrix decoded to four channels by the DMA8 Plus. What I'd like to be able to do is to get Quicktime Pro to output a Dolby Digital, or Dolby E but I think that's unlikely, bitstream to the DMA8 Plus, so I get the full multi-channel sound. If I take the Quicktime file into Compressor I can export the sound in Dolby AC-3 format, and this will play in DVD Studio, though I've only tried playing it on the two internal speakers in the laptop. What I'd like to be able to do is to replace the original AAC track in the Quicktime file with the Dolby Digital one, and then get Quicktime Pro to output this encoded bitstream to the DMA8 Plus. Any suggestions?

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Peter David Bruce
Expert Film Handler

Posts: 187
From: East Anglia -England
Registered: Aug 2007

posted 08-20-2007 11:36 AM

Hi Stephen,

I used to work for apple in their audio rooms and even with all my experience in Quicktime Pro I have not tried what you request here. I do suggest calling Apple Technical - not sure of the number.

But they do have a department for audio/video conversions and repro so it might be an idea to give them a ring. I believe it can be done - however as of yet here in east anglia we have no mainstream digital projectors to hand for us to try.

All the best mate, speak soon.
Peter Bruce

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Stephen Furley
Film God

Posts: 3059
From: Coulsdon, Croydon, England
Registered: May 2002

posted 08-20-2007 02:29 PM

Hi Peter; first post I see, welcome to the forums.

Thanks, I'll try to find the right people at Apple to talk to about this. The optical output is certainly capable of carrying a Dolby Digital bitstream, as I've done it from Power DVD running under Windows. I've got both Windows XP and Apple System X on the laptop.

You're from Duxford I see. Have you been to the cinema that the Projected Picture Trust run at the Imperial War Museum place there? I don't think they give public shows there any more, and I've never been because it seems to be difficult to get to by public transport.

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