Film-Tech Forum ARCHIVE: EPISODE II: what sound format did you use ? PCM 6ch, Dolby EX, DTS ES ?

This is topic EPISODE II: what sound format did you use ? PCM 6ch, Dolby EX, DTS ES ? in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by David Baum (Member # 568) on 05-20-2002, 12:01 PM:

TI seems to say all digital projections use uncompressed 24bits PCM on six channels ( uncompressed PCM is sort of a pleonasm

I suppose not every theater had access to this super high res sound format and dolby and dts was often used instead.

Posted by Antonio Marcheselli (Member # 373) on 05-20-2002, 12:59 PM:

In Italy Fox didn't print SDDS track this time.

I'm using DTS at the moment.

Bye
Antonio

Posted by Manny Knowles (Member # 1171) on 05-20-2002, 01:02 PM:

I feel pretty darn good about being able to present EPISODE II in DTS (2 locations) and Dolby Digital EX (1 location).

But, then, I'm also running 35mm film.

------------------

~Manny.

Now...where was I ?
Leonard Shelby, MEMENTO.

Posted by David Baum (Member # 568) on 05-20-2002, 01:05 PM:

hi Antonio

it "seems" the compulsory or prefered at least sound format accompanying the digital film is PCM. and backup or "second choice" being dolby, sdds, dts.

can anyone clarify this ? is there a synchronisation issue or is the prefered PCM track recommended by TI "one" of the reasons why there's so few 3DLP (aside from the cost but a quality argentic projector ain't no bargain either... ). Are dolby, dts for instance a bit "unhappy" because PCM encoding format has been the reommended choice by TI ? .....

Posted by David Baum (Member # 568) on 05-20-2002, 01:48 PM:

argh! I'm sorry, I meant "which sound format did you use with the 3DLP digital projection" ?

Posted by Scott Norwood (Member # 30) on 05-20-2002, 07:20 PM:

I didn't know that there were different sound formats for DLP. The Qubit that I've seen has discrete 6-channel outputs. I don't know about the Boeing or Technicolor systems.

It would probably be trivial to make this work with a standard DTS player (as long as the timecode matches up), but I can't see it being worth the bother. If anything, Dolby or Sony or DTS would probably just license their compression technology and the actual playback would be done off the hard disk.

Posted by David Stambaugh (Member # 1102) on 05-20-2002, 07:30 PM:

Get rid of as much of the outboard hardware as possible!! It's just more stuff to get screwed up.

Theaters are begging for a "black box" system with a green "START" button. That's all they seem to be able to handle, and it fits in perfectly with their policy of having the absolute minimum investment in training their personnel.

"Can you tell time? Can you press this green button? Congratulations, you are booth-certified!"

Posted by Bobby Henderson (Member # 840) on 05-20-2002, 07:56 PM:

I thought the audio format for digital projection shows was 20-bit 48kHz 5.1 EX. 24-bit would be a bit surprising, although more and more music and movie audio masters are being archived at that bit depth. Too bad nearly all but the most profanely expensive of high end electronics products can get close to displaying true 24-bit dynamic range. I would say 20-bit is enough.

Also, I was under the impression the 5.1 PCM audio stream is part of the overall digital projection data stream, much in the manner that a DVD Video .VOB file contains both an MPEG-2 video stream and a number of DD, DTS or PCM audio streams.

Posted by Matt Close (Member # 996) on 05-20-2002, 09:45 PM:

TI is using PCM for DLP???? .. hmmmm .... Excuse me as I really know nothing about the DLP scene, but wouldn't it make more sense to use a relatively 'lossless' audio compression like DTS and devote as much bandwidth as possible to picture quality?

Posted by Steve Kraus (Member # 476) on 05-20-2002, 11:43 PM:

Picture quality? Since when is digital projection about picture quality?

Posted by David Baum (Member # 568) on 05-21-2002, 03:35 AM:

http://www.dlp.com/dlp/cinema/Specs.asp?mid=143

they say that the audio is "normally" stored as 6ch PCM 24bits

thus, not "necessarily" ...

the image is stored on 4 HD drive for a total of 72GB.

Posted by Bobby Henderson (Member # 840) on 05-21-2002, 11:58 PM:

A 150 minute long film with 24-bit 48kHz 6.0 channel audio would require 7.7GB of space to store the audio data (864 kilobytes per second --not bits).

Posted by Paul Linfesty (Member # 214) on 05-22-2002, 12:31 AM:

It's confusing, though, to the public about soundtrack format, as the LA Times ad has the three (SRD, DTS, SDDS) digital formats listed as playing with the DLP presentations.

Posted by David Baum (Member # 568) on 05-22-2002, 03:43 AM:

really confusing!

some people say that on top of the cost of a new digital projector (+ server etc), the fact that PCM is the prefered recommended "by default" sound format "irritates" Dolby and Dts and Sony (SDDS) and thus "also" explains why there so few 3DLP projectors around the world ( Lucas was shocked when he was told the low nr of 3DLP-equipped theaters ... ).
not a fact, just heard it.

Posted by John Hawkinson (Member # 1135) on 05-22-2002, 09:56 AM:

Matt (Close), I think you're a bit confused.

PCM is Pulse-Code Modulation, and is an encoding scheme, but not a compression scheme. It is in fact just an encoding, compare it with Mu-Law or U-law, etc. So if you're looking for "lossless," PCM certainly is that.

DTS does in fact use compression.

In DLP, basically your storage space is huge, so there is really no reason to worry about compressing the audio -- any audio will be so dwarfed by the size of the video that compressing it or not compressing it is probably irrelevent.

Furthermore, just because it's PCM doesn't mean there isn't compression being applied to it (though it probably means that it is lossless compression, if anything).

--jhawk

Posted by John Pytlak (Member # 331) on 05-22-2002, 10:09 AM:

If Bobby Henderson's 7.7GB estimate for uncompressed 24-bit audio is accurate, that's still almost 10% of the data load, and hardly negligible.

------------------
John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Research Labs, Building 69, Room 7525A
Rochester, New York, 14650-1922 USA
Tel: +1 585 477 5325 Cell: +1 585 781 4036 Fax: +1 585 722 7243
e-mail: john.pytlak@kodak.com
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Posted by John Hawkinson (Member # 1135) on 05-22-2002, 10:13 AM:

I dunno; to me, an 80gb drive versus a 90gb drive doesn't seem like a big issue.

It's also hard to believe there isn't some lossless compression going on, since it seems implausible that there's a lot of information in all 6 channels simultaneously all the time.

--jhawk

Posted by Keith Davidson (Member # 1157) on 05-22-2002, 11:46 PM:

Lossless compression????

Posted by John Hawkinson (Member # 1135) on 05-22-2002, 11:48 PM:

Yes, "lossless compression" -- that's like when you have "00000000000000000000" that gets replaced with an encoding that means "20 zeroes."

--jhawk

Posted by John Pytlak (Member # 331) on 05-23-2002, 07:40 AM:

jhawk said: "I dunno; to me, an 80gb drive versus a 90gb drive doesn't seem like a big issue."

The issue isn't so much one of storage, but of delivery. Today, it still means a few extra DVDs or longer download time.