23,98 footage - Do I have a problem?

[Seanzzxx]

Kind people -

First of all, let me say DCP-o-matic is awesome, it lets beginning filmmakers like me deliver films in DCP format and it works like a charm. Having said that, I think I might have messed up and wonder how big the trouble on my hands is.

I have a project which was filmed in 23,976 needs to be delivered in DCP. Do I have a problem with the audio syncing if I do the DCP at 24 frames? Should I render out the original project (in Resolve) at 24fps and will the audio then speed up automatically? I assume a pitch shift is unneccesary at those speeds?

Thank you guys so much.

P.s. is there any way to predict the file-size, based on the original file's size for example?

[carl]

I have a project which was filmed in 23,976 needs to be delivered in DCP. Do I have a problem with the audio syncing if I do the DCP at 24 frames? Should I render out the original project (in Resolve) at 24fps and will the audio then speed up automatically? I assume a pitch shift is unneccesary at those speeds?

No problem, DCP-o-matic will make a 24fps DCP and sync the sound by running it slightly fast. You don't need to do anything.

P.s. is there any way to predict the file-size, based on the original file's size for example?

The DCP's size is mostly the video, whose bitrate is specified in the DCP tab in Mbit/s. Hence you can get a rough estimate from that. e.g. 1 hour is 3600 seconds which at 100Mbit/s is 3600 x 100 / 8 megabytes i.e. about 45Gb.

[Carsten]

No problem there - DOM will conform your image frame rate to 24fps and apply a slight resampling to the audio to make it fit.

File size estimation is virtually impossible - unless all you want to know is a very rough estimate.

The compression datarate you specifiy in DOM does not translate straight into a filesize.

While many people say they see no improvement in higher rates than 150MBit/s, I usually do not bother much and always use 230MBit/s. That's safe for all equipment in use, and I don't care if I waste some space. Effective data rate depends highly on image resolution/container size and image high frequency content. The only reason you would want to play around with this is if for some reason you need to meet a hard target, like a special size/capacity of USB stick/SSD for instance. Then you simply need to test, or create e.g. three different versions at different settings and see which fits best.

- Carsten

[Seanzzxx]

Thank you guys so much for the swift replies, it really means a lot. Are there any problems with frame interpolation or ghosting that I have to worry about with this framerate change?

[carl]

No, the video frames stay exactly the same, they just happen more often. The sound is resampled but the effects of this are inaudible unless you are really trying.

[Seanzzxx]

Thank you so much for the reply. One completely different question - our movie is 2:1 aspect ratio (yeah, we're stubborn...). Would I be correct in assuming that we would have to deliver this within the 1.85:1 aspect ratio and just accept the slightly smaller frame?

[scorpio81]

Hi.
Doing some calculations reveals that Flat container is the best choice.
Look for yourself: 2:1 AR will be 1716x858 in Scope and 1998x999 in Flat. So Flat will have slightly higher resolution.

[carl]

It might also be worth noting that if a cinema has a common-height screen your 2:1 may look a little better if you put it into a Scope container. It would just be 1.85 but a little wider.

Unfortunately if the cinema has common height I think using Scope for your 2:1 will make things even worse...

So it probably depends on whether you are playing in one venue or many.

[Seanzzxx]

Thank you guys so much for the advice. One final (hopefully) question: can I make a DCP from a Prores file on Windows?

[carl]

Yes, that should work fine.