2K or 4K cinema films in the home - Page 2 - AVS Forum
Forum Jump: 
Reply
 
Thread Tools
post #31 of 34 Old 01-29-2012, 03:53 AM
Senior Member
 
Tony_Montana's Avatar
 
Join Date: Mar 2011
Posts: 382
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 15
Quote:
Originally Posted by Ryan711 View Post

Just curious as to if that, assuming all other things being equal, would provide a noticeably better picture quality over a standard bluray due to what I assume is a less compressed copy than what would be found on bluray.


it`s a matter of digital processing & storing video files.
DCI files have a lot more video information than BDs.
Its not only the higher frame rates & resolutions that
increase the file size, its also the video information.
The .pdf that 707 posted writes
that dci movies store 12 bit color information per pixel (native deep color )
when bds store 4:2:0 8bit. This is a lot more GBs
(The color gamut is also wider.)


at last, there is no audio codec.
The audio files are uncompressed lossless PCM tracks.


all these facts increase the video file size.


i will copy paste it directly from the .pdf (p.69)

Quote:


Capacity



Excluding storage necessary for redundancy, the storage system is required to provide
for, at a minimum, the storage of three features (including pre-show content) per screen
(one feature currently showing and a second or upcoming feature). Shown in Table 9
below, are some example storage requirements. The numbers are based on:




One three-hour feature
  • 20 minutes of pre-show material at the same resolution
  • 16 channels of uncompressed audio at 48 kHz at 24 (AES3) bits
  • 3,000 sub pictures in PNG file format
  • 3,000 Timed Text lines


Average Bit Rate (Mbits/sec) 3 Hour Image (GBytes) 3 Hour Audio (Gbytes) 20min pre-show (Gbytes) Sub Picture(Gbytes) Timed Text (Gbytes) 3 HOur (Gbytes)
250 337.500 2.074 37.500 0.300 0.001 377.374
200 270.000 2.074 30.000 0.300 0.001 302.374
125 168.750 2.074 18.750 0.400 0.001 189.974
100 135.000 2.074 15.000 0.600 0.001 152.674
80 108.000 2.074 12.000 0.800 0.001 122.874


Table 9: Example of Storage Capacity for one 3-Hour Feature (12 bits @ 24 FPS)

  • Image size: Calculated by: {Average or max bit rate (Mbits/sec) * hours * 60 min/hour * 60 sec/min} / {8 bits/byte *1000} the results is in GBytes
  • Audio size: Calculated by: {32 (AES bits) * 48,000 samples/sec *16 (channels) * hours * 60 min/hour * 60 sec/min / 8 (bits/byte) = size or
    Calculated by: {32 (AES bits) * 96,000 samples/sec *16 DCI Digital Cinema System Specification v.1.2 Page 70 (channels) * hours * 60 min/hour * 60 sec/min / 8 (bits/byte) = size
  • Sub Picture size: Calculated by: 100,000 (bytes/png file @ level 1) * 3,000 (subtitles/feature) = size
  • Timed Text size: Calculated by estimate of 1 MBytes per feature


more bits always mean more information
more digital often means better quality
Tony_Montana is offline  
Sponsored Links
Advertisement
 
post #32 of 34 Old 01-29-2012, 05:01 AM
Newbie
 
raus's Avatar
 
Join Date: Feb 2010
Posts: 12
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Apart from color space and a few pixels (for 2K, not 4K of course), there is no great difference, DCI files are just treated as series of single frames, while on BD they are treated as a film so some frames do not contain the whole information (while each and every DCI frame can be viewed separately, as a jpeg2000 file) and that's why they are smaller, not because there is an abyss in quality between them.
I think that a 250 GB DCI movie could be compressed to some 130-150 GB (which is soon to be available for BD) with a loss in quality close to none, yet that would demand greater computing powers (and DCI server has to decrypt, process and encrypt the frames in time close to real, all that on specialised chips (encryption), not normal CPU/GPU-s)
raus is offline  
post #33 of 34 Old 01-29-2012, 10:47 AM
AVS Club Gold
 
Alan Gouger's Avatar
 
Join Date: Jan 1999
Location: Florida
Posts: 18,728
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 16
Quote:
Originally Posted by raus View Post

yet that would demand greater computing powers (and DCI server has to decrypt, process and encrypt the frames in time close to real, all that on specialised chips (encryption), not normal CPU/GPU-s)

You bring up a good point, it is amazing how a D-cinema server plays along flawless 24fps where a top consumer CPU/GPU judders and cannot get out of its way regardless the cost, the very best still drops frames.
With a D-cinema server is it the hardware that makes it so different from your typical CPU/GPU, the software or is it the source that results in perfect fps playback.
Alan Gouger is offline  
post #34 of 34 Old 01-30-2012, 07:17 AM
Newbie
 
raus's Avatar
 
Join Date: Feb 2010
Posts: 12
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:


With a D-cinema server is it the hardware that makes it so different from your typical CPU/GPU, the software or is it the source that results in perfect fps playback.

First the source material - it's just an archive with jpeg2000 frames, no motion extensions like in mpeg4. Secondly the hardware - for security reasons AFAIK there must be an external decoder card which gets the encrypted images, internally decrypts them, render (just single frames, 24 per second), decrypts (for server-projector link) and passes on.
raus is offline  
Reply D-cinema Equipment and Theaters

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off