Film and MPEG4

Jon O'Brien · April 1, 2018

Are the best-looking examples of scanned film that you can see online, on Youtube and Vimeo, all MPEG4? Like Indiana Jones said, "You know the one I mean?"

For showing your work online, and editing/grading using a PC, what's the best way, in your opinion, to get scanned 16mm footage out there on the web, looking its absolute, 'real-film', best? How does MPEG4 affect the definition of the image? What definition is possible? My S16 footage shot late last year was scanned at 2.5K and was rendered in ProRes4444. Attempts to edit and colour grade the image on Davinci Resolve have so far not produced satisfactory results, probably because the computer can't handle the large file size. A friend has now converted the file to MPEG4 using a free program called Handbrake. Are we on the right track?

Brian Drysdale · April 1, 2018

No, you should ensure that all your monitors are correctly calibrated when grading your film. Handbrake is dumping data, so reducing the quality if your film, you don't want to using that at this stage, Handbrake is good for converting variable frame rate footage (eg phone videos) to constant frame rate or making highly compressed streamed video usable for editing or compressing video, but not for your master..

You may have to look at your computer, Davinci Resolve can be demanding in computer power, especially when grading, I gather less so when being used as an editor. Have you tried using proxy files?

Tyler Purcell · April 1, 2018

Most MPEG formats use Long GOP compression, which means there aren't actual frames. It takes a full-resolution sample of one frame and then only records the differences between that frame and the next 18 - 24 depending on the style. So for editing, Long GOP is basically the worst format. Also quality wise, it's the worst as well, mainly because it's 8 bit 4:2:0 color space, which gives you very little dynamic range to work with.

DaVinci needs a minimum of 4gb video memory and it prefers nVidia Cuda video cards, the lowest/cheapest would be a GTX980 in my opinion. That's kind of a "requirement" to make it work. DaVinci doesn't really need much CPU power, it uses the GPU for mostly everything outside of the GUI, which is part of the reason it's such a powerful program.

Pro Res 4444 needs around 100Mbps to stream at 2.5k, which means it kinda caps out on a USB drive, but an internal 6Gbps sata drive should work fine. My scans are 4444 Pro Res and I have no problem playing them back on a single drive.

So no, converting to MPEG files is pretty much the worst thing you can do. However, DaVinci does make DNX files internally, so you could put the files in DaVinci, make a timeline and export that timeline as a lower-quality DNX-SQ 4:2:2 10 bit format. I think that's 175Mbps on DaVicin's menu or standard Pro Res, which is the same bit rate. You should also adjust the sequence to be 1080p instead of 2.5k because that will help a lot with bandwidth when you're exporting. A 1080p 24fps DNX or Pro Res 175Mbps file should have zero problems playing back on your system. It would also be an unnoticeable quality difference.

As suggested above, DaVinci proxy files are another way to go, but they are also pretty large and if DaVinci isn't working properly, the files are worthless to any other editing software. So it's better to at least convert to something that can be used with Avid, Premiere, Final Cut Pro and DaVinci.

Jon O'Brien · April 3, 2018

Thanks so much guys. Great information. Sigh. Looks like the answer to it all is to buy a much more powerful computer. Just can't do that at the moment. Anyway, my friend has got the footage edited using a free program, so hopefully we can get this posted soon, once the soundtrack is done. It's only a 2 minute film, really just a first test of the Bolex Rex 5 and lenses, and getting my film skills going again, but it turned out okay to use as a music video. I'm okay with the photochemical side but, with computers, my knowledge extends only to things like Word programs. I'm digital video challenged, but making some good progress. With patience I should be able to work all this out eventually.

Jon O'Brien · April 8, 2018

Just out of curiosity, what would be a dream computer outfit for digital editing and colour grading, fully professional set-up, specifically for film projects eg. 16mm for top-quality film results posted on the web ... not necessarily for cinema release, but sure why not talk about that too. What would these computer set-ups cost? I realise that cost can vary a lot depending how you build the system, but some general advice is all I'm asking for, to get an idea.

Edit: and that might expand one day to 35mm footage as well. Probably doesn't make any difference, but just in case ...

Edited April 8, 2018 by Jon O'Brien