Film-Tech Forum ARCHIVE: Deluxe using new digital cinema compression?

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Posted by Jarryd Beard (Member # 2543) on 07-26-2007, 02:58 PM:

I've noticed a couple recent titles released by Deluxe that are significantly smaller in file size. For instance, Harry Potter and Hairspray were 61 GB and 51 GB respectively. I did not notice a decrease in image quality... like it may have been below the 2K standard. Anyone heard anything more about this?

Posted by Bastiaan Fleerkate (Member # 3826) on 07-30-2007, 07:52 AM:

Maybe because HP is longer (in time) then Hairspray????

Posted by John Wilson (Member # 269) on 07-30-2007, 08:40 AM:

No, they are indeed smaller than previous files of other similarly lengthed movies.

Posted by Jarryd Beard (Member # 2543) on 07-30-2007, 11:41 AM:

To clarify, both titles in my first post seem to be of smaller file size. For instance, with Harry Potter running running 138 min, I would have expected the file size to be closer to 200 GB.

Posted by David Zylstra (Member # 4230) on 07-30-2007, 04:04 PM:

The files are definitely 2K - with the push to get things DCI compliant the studios would not take a step backward (a lot of the snafus I saw last year with digital were upgrade related due to studios insisting on certain DCI features being available for their new release before a full QC could be done) and all of the 2K projectors out there are most likely not set up to accept a lower resolution from the playback server without modifying the input settings on the projector.

I know there were many studio and lab people surprised at how far Harry Potter compressed. I think there are several factors that play into file size - amount of on-screen action, how many scenes were CGI painted with a limited colorset, amount of bright or dark scenes, flat or scope, scope encoded at 858X2048 resolution or encoded "full container" at 1080X2048 letterboxed, 2K or 4K, live action or cartoon, is the source truly XYZ colorspace or lower, how hot the soundtrack is, etc . . . .

Posted by Lyle Romer (Member # 1266) on 07-30-2007, 07:54 PM:

quote:
there are several factors that play into file size - amount of on-screen action, how many scenes were CGI painted with a limited colorset, amount of bright or dark scenes, flat or scope,

The biggest factor is that they are probably using variable bit rate encoders. I'm sure some of the factors that you listed come into play in the final file size but "amount of on-screen action" is not one of them. The JPEG-2000 compression specified by DCI encodes each frame as if it was an independent still picture. It is completely motion independent.

Posted by David Zylstra (Member # 4230) on 08-01-2007, 08:14 AM:

Yes, you are right on the "on screen action", my bad, I was pulling knowledge from MPG encoding where action would affect file size . . . . . I probably should have said that films with more action scenes that are bright and full of explosions (aka Die Hard) could carry the need for more color and contrast information than a darker film.

Posted by David Graham Rose (Member # 1450) on 08-02-2007, 08:37 AM:

Greetings All

HP5 was variable bit rate (VBR enc)encoded and thus has a much lower file size. Pirates 3 was not variable bit rate encoded and therefore was about 300Gb.

David