Friday, July 20, 2007

Mastering Digital Cinema

The crew at CineForm has been very busy over the last four days. As intended, we trans-coded and up-converted all the 48 Hour Film submissions for the San Diego division of this international film festival. We had a total of 47 entries (including our own) and nearly 47 different video formats, compressions types, frame rates, frame resolutions and aspect ratios. This was a bigger can of worms than I had predicted, as filmmakers/editors in a rush make a lot of mistakes. CineForm, as a major local sponsor, wanted all the films to look their best when output on the Sony 4K projector, yet the conditions of this competition--think Iron Chef for filmmakers--does conspire against our goals to make the pictures really pretty. That said, many of the pictures did look awesome, and basically every film was improved by our up-conversion, resulting in many happy filmmakers. The audiences cheered and clapped each time our tag was shown, but even more enthusiastically when shown the second time at the end of each night's screening (that felt nice.) Thank you Geoff Pepos of Rogue Arts for making our 15-second tag -- I hope to post that for others to see soon.

The project was presented by a portable Wafian DDR, the HR-F1. This makes a very nice playback server now that there is a play-list feature (that feature is still beta.) In each session, there were around 10 films, with 5-6 other reels for 48 Hour promotion materials and other sponsor advertisements. The Wafian box performed flawlessly.

Here is a cross section of the formats we had to deal with :

DV 60i, 24p, 24pA, mixed 24p/24pA/60i, in 4x3, 4x3 letter boxed, 16x9, mixed aspect ratio (some not intentional), wrapped in MOV or AVIs, recoded to H.264 (at the horror of 256mb/s). We had Apple Intermediate codec encodes as 30p (we said no to 30p as this was for a 24p presentation, yet we had 3-4 films submitted that way), we had a couple of ProRes movies, and range of 720p24 DVCPRO-HD materal, some coded at 60p . We had a surprising number of clips mastered at 24.000 and 30.000 fps -- how or why they did this, I have no idea -- the cameras were standard 23.976/29.97 shooters. Very little 1080p at 23.976, our presentation format, four at most (our own film being one of them.) That was picture data; audio was a whole new set of issues. Converting it all was actually a lot of fun.

We learned a lot during this process, and I expect there will be several enhancements made to our own products to ease the conversion for a wide range of source material. We actually produced code over these last few days to deal with pulldown and framing issues we saw.

Some take-aways for filmmakers entering these competitions:

1) Choose a video format before you start shooting and stick with it. And for 24p presentation don't mix 60i and 24p sources.
2) Don't letterbox a 16x9 movie into a 4x3 frame; that just wastes resolution -- I know some cameras force you to do it and this is actually recommended by the 48 Hour Film web site. This causes another issue in you have a 16x9 sources and render to 4x3, any re-frame (zooming into a shot) will make your letterboxing size change between scenes -- there were 2 or 3 films with that issue.
3) Stop the lens down, or use neutral density filters; many movies had large, clipped white regions that could have been avoided to achieve a more filmic look.
4) If you want a really dark look, still light your scene well and make your film dark in post; we saw lot of source compression artifacts in the shadows of dark films.
5) Basically for items 3-4 there is only a small range of light that works well for most low cost video cameras; try for the camera's sweet spot. That might mean you need to gel your windows for interior shoots.
6) Don't use heavy compression on your output, don't export to MPEG2, MPEG4 etc. for your deliverable -- use that for your YouTube uploads.
7) Shoot HD 24p if you can, as it looks great on the big screen.

This was an awesome experience and I hope we get the opportunity again.


Richard Fox said...

David, Thanks for all the hard work that you and your team from Cineform and Waifian did.

It was a real thrill to see our film as well as the others on the big screen.
Even with technical imperfectioms the experience was wonderful.

David said...

Thanks Richard,

I think the audience got a kick out of your movie, as it was the only one to boldly green screen nearly everything. And the pictures do look awesome presented that way.

Cail said...

Hey, I entered 48 Hours ages ago when I was living in SD. Good to hear it's been beefed up quite a bit since!