DCP File Size Expectations

[johnc12426334]

Hello,

I recently exported a Wraptor DCP out of Premiere for a feature film at runtime 110 minutes in 2K Flat (1998x1080) and in 5.1 audio. After browsing other forums regarding DCP File Size, I thought I should expect an overall DCP folder file size of somewhere between 175-220 GB but checked my rendered DCP and saw it was completed at 53.81 GB.

After checking other adobe forum discussions, it seems others have noticed smaller file sizes than expected and they have seemed to play fine in theaters. I'd just like to know if there is a standard expectation of DCP file size for a feature film of this length at 2K Flat 5.1, and why Premiere seems to render at these proportionally smaller files sizes. I assume, given the lack of custom options for bitrate setting being anything other than 250 Mbps, there isn't much to tweak in export settings?

Thanks.

[johnc12426334]

Also for reference - Premiere gave an expected DCP file size of 1368074 MB which I believe is 1.37 TB? Also substantially larger than the ~200 GB expectation.

[Warren Heaton]

All that is known at the time that an estimated file size is caclulated is that no single frame will exceed the peak image bitrate.   The estimaged files size is great for determining the most amount of space that the resulting DCP might require, but there's no way to know for sure until it's encoded.

For example, at 24 frames per second with a peak image bitrate of 250 megabits per second, no single frame will exceed 1/24 of 250 and many frames will be less than that.  The actual bit rate of each frame will be something less based on what is happening within the picture (spatial compression) and between the pictures (temporal compression).  For 110 minutes at 24 frames per second at a peak image bitrate of 250 megabits per second we can calculate that the file may be up to 196.36GB, but we can't know how large it will actually be until we've encoded it.

Another example:  58.01GB is an expected size for a 110-minute 2K DCP movie at 75 Mbps, but the actual file can be expected to require less than 58.01GB.

[johnc12426334]

Thanks for your response, Warren. That all makes sense. I could play back the .mxf video and audio files in DaVinci Resolve and it looks like everything's there with sufficient quality.