Film-Tech Forum ARCHIVE: dcp specification

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Posted by Allan Riddelll (Member # 5090) on 03-23-2015, 09:48 AM:

Recently it was decided to transfer our pre show advertising from DVD to DCP. After ingesting the DCP successfully onto the Doremi server, it was found that sound and picture were playing far too slow despite a transfer of 24 FPS which I understood to be the appropriate frame rate. Can anyone supply the appropriate specs for sound and picture.

Posted by Carsten Kurz (Member # 5396) on 03-23-2015, 10:10 AM:

Which software did you use for the conversion and what format (codec, origin) was your source footage?

- Carsten

Posted by Mike Blakesley (Member # 26) on 03-23-2015, 10:31 AM:

Most likely, your preshow was created at a higher frame rate like 30 so a 24 frame rate DCP will play too slowly. You need to create the DCP at the same frame rate as the origin footage. Just make sure your projector will play that frame rate.

Posted by Jim Cassedy (Member # 4115) on 03-23-2015, 10:47 AM:

There's a difference between rendering a DCP at 24fps, and transcoding
or re-sampling video from some other frame rate to 24fps.

I don't know what television standard is used in Malta, but here in the US
we use NTSC at 30fps. If I simply tell the DCP program to output at 24fps
it will simply slow down the video & audio playback from 30 to 24fps , which
sounds like what is happening to you.

What first has to be done
is that the video & audio have to be run through a program or an electronic
frame rate conversion system which will re-sample and do some sort of
digital interpolation to properly convert your frame rate to 24fps,
and then render the DCP at that rate.

>>>But- - do you REALLY need to do this?<<<

Using my USA NTSC/30fps frame rate as an example-
30fps is a valid DCP frame rate. It's not the "standard" DCP distribution
specification, but I've only encountered ONE system in the past two years
that was 'locked' to 24fps and would not play back 30fps DCP's.

Valid DCP frame rates are 24, 25, 30 & 48fps Almost all systems can play these.

So if you are just doing this for yourself, or your own theater, there's really no
reason I can see why you can't just encode your video at whatever frame rate
works for you, on your own system.

I do this all the time, with no problems, with theatres that I'm directly
involved with. But, if you are encoding something for general distribution,
you really must do some sort of 'frame rate interpolation conversion' to
24fps to meet the DCP specs and assure 100% compatibility and
interoperability with all DCP systems everywhere in the universe.

Posted by Fernando Caldeira (Member # 5680) on 03-24-2015, 07:29 PM:

Just use DCP-o-matic and all all problems will go away... [Smile]

Posted by Monte L Fullmer (Member # 2797) on 03-24-2015, 08:48 PM:

+1 For "DCP-O-Matic"

I have to create 10, 30 sec spots, which the source is in MP4 format to target them as DCP content, using the program above, to use with our system.

-Monte

Posted by Stephan Shelley (Member # 8587) on 03-25-2015, 05:17 PM:

Dolby DSS/DSP 100 will not do 25 or 30 fps in jpeg 2000 but will in the older mpeg2 format.

Posted by Carsten Kurz (Member # 5396) on 03-25-2015, 06:05 PM:

Even DCP-o-matic can't solve the issue of 30fps->24fps conversion...
Yes, it will create a 24fps, but slowed down. Better to check if your machine supports 30fps (use SMPTE packaging), and leave it at 30fps (or whatever the native framerate of your source footage is, as long as it is any of the supported rates).

- Carsten

Posted by Gordon McLeod (Member # 33) on 03-25-2015, 06:49 PM:

what about using handbrake to do the frame rate conversion

Posted by Grant Chambers (Member # 7051) on 03-25-2015, 11:08 PM:

I use After Effects to convert the frame rate, then export as tiff sequence 16 bit. Then render the sequence in open DCP to jpeg2000, etc, etc. Never had an issue.