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» Film-Tech Forum   » Operations   » Digital Cinema Forum   » gdc server and mpeg

Author Topic: gdc server and mpeg
Dave Ganoe
Expert Film Handler

Posts: 119
From: Point Marion, PA
Registered: Jun 99

 - posted 08-12-2007 02:54 PM      Profile for Dave Ganoe   Email Dave Ganoe   Send New Private Message       Edit/Delete Post 
I have access to a gdc server and tried uploading a trailer in mp4 format. When I go to import the trailer to the server I get an error that says "unable to read FW header". Anyone have any suggestions?

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Tristan Lane
Master Film Handler

Posts: 444
From: Nampa, Idaho
Registered: Feb 2002

 - posted 08-13-2007 11:19 PM      Profile for Tristan Lane   Email Tristan Lane   Send New Private Message       Edit/Delete Post 
This won't work for a number of reasons:

1- Depending on the model of the server, it will not do MPEG4. MPEG2, Motion-JPEG, and JPEG2000 are the commonly used. The newer models only accept JPEG2000 and MPEG2-DCP formats. This holds true for most manufacturers.

2- Aside from your MP4 file not being the right format, it is not packaged correctly. D-cinema servers require all content to be packaged in either an MXF or DCP container. You'll notice if you look at the file extensions of normal content, it will carry a .MXF or .DCP extension. These formats contain a header, the raw data, and a footer. The header contains information on the file as well as metadata for encryption, if needed.

The DCI spec has useful information on how the MXF and DCP (D - Cinema Profile) packages work. Wikipedia also has information on the MXF container.

Edit: I suggest you convert the file to MPEG-2 4:2:0 and figure out how to package it correctly. If you are using the SA-2100 server, it will only accept DCP packages.

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Patrick de Groot
Expert Film Handler

Posts: 161
From: Sprang-Capelle, Netherlands
Registered: Apr 2001

 - posted 08-14-2007 05:04 AM      Profile for Patrick de Groot   Email Patrick de Groot   Send New Private Message       Edit/Delete Post 
I really don't get it why a DC server only play a few file formats. Alternative content? Sure...

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Bobby Henderson
"Ask me about Trajan."

Posts: 10940
From: Lawton, OK, USA
Registered: Apr 2001

 - posted 08-14-2007 09:23 AM      Profile for Bobby Henderson   Email Bobby Henderson   Send New Private Message       Edit/Delete Post 
For playing other kinds of content, such as personal computer-based video files or stuff off of standard DVD, you need to use whatever auxiliary input is available for your projector and server. You can't program it directly into the server itself.

The Christie/AccessIT package can accept inputs from other computer sources (for things like PowerPoint presentations, etc.) and from standard DVD players as well. The results don't look nearly as good as real 2K JPEG2000 content. But it works.

I would be surprised if any of the other major digital cinema systems lacked auxiliary input capability.

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Tristan Lane
Master Film Handler

Posts: 444
From: Nampa, Idaho
Registered: Feb 2002

 - posted 08-21-2007 01:44 AM      Profile for Tristan Lane   Email Tristan Lane   Send New Private Message       Edit/Delete Post 
quote: Patrick de Groot
I really don't get it why a DC server only play a few file formats.
I used to ask the same question...

Then I realized that the projectors [as well as the servers] did all processing in the digital realm. There is no analog video processing on any of the d-cinema projectors. The capabilities of video format/compression schemes varies greatly. To make a server capable of playing back many user-grade formats would require countless additions to the operating software and hardware of the server. All of these extra features would probably be cost prohibitive to use. This would also eat up valuable resources within the server or projector that should be devoted strictly to d-cinema content to ensure reliable playback of feature films. I imagine that down the road servers will become more flexible, but not at the moment.

The solution to this is to use a 3rd party video scaler. Scalers can range in price from over $5000 (for the do everything ever imagined model) to $200 bucks for a specific interface (does 1 thing model). Most projectors used today provide DVI-D inputs for alternative content. The responsibility is left up to the consumer to provide a correctly formatted signal to the DVI input. Keep in mind that the projectors have no upscaling ability (they can compress an image down, but can't make up for lost pixels). Therefore, if you wanted to make a 1024x768 or 480i image fill the whole screen, a scaler is needed to format the image to better fit the projector's native chip resolution. The most economical solution is to buy a Gefen 1080P VGA 2 DVI scaler. It will accept most component video signals (with an adaptor) as well as most video signals that are put through an HD15 connector. The scaler will come very close to filling the entire chip, and as long as your incoming video resolution matches the presets on the scaler. I've been asked a few times what is the best way to interface an XBOX 360 to a projector, and the Gefen VGA2DVIS scaler is always the most economical solution. A theater that I know of has also used these scalers for advertising content and HD-Cable broadcasts of sporting events.

In order to achieve full 2K upscaling, a Christie Cine-IPM2K scaler (or equivalent) is needed. Basically it will take any signal from composite video up to HD-SDI formats and scale it to full 2K resolution so that no changes are needed to lenses or masking. It won't make a crappy standard definition image look better, but it will format it correctly so that no motion artifacts are seen. It is probably one of the most capable scalers on the market next to Folsom scalers (Folsom Research is related to Barco in some way.)

Probably more info than you wanted.... but there you go. Alternative content is very easy to present, as long as you've got the correct equipment.

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