davidferguson
https://www.theppt.org/rewind/articles/where-can-you-watch-t...
But here are my nit-picks from the article linked here. I'm only commenting on the 15/70mm IMAX parts, because I'm not knowledgable enough about the digital IMAX foramats.
> The extra resolution, up to 18K equivalent
The claim of 18K is entirely untested. No one has ever measured what the theoretical resolution of an 15/70mm IMAX system is. Kodak's film may me theoretically capable of resolving this, but what about the camera lens, the GT projector lens and field flattener, and everything else involved? Until a study is actually done, I don't think the 18K is a good number to band about.
> thanks to the use of single or even dual 15kW water-cooled xenon bulbs
No cinema is using dual lamps. The dual lamps are used for 3D - one lamp per "eye" (right and left). But no 15/70mm IMAX is currently showing 3D, I think the last was the London Science Museum (but that's a guess, so don't take as truth). So it is only single lamp. 15kW is also not always true - some smaller 15/70mm IMAXes use 12kW or around that.
> However, there are only around 24 such theaters in the US, nine in Canada and six elsewhere around the world.
This is incorrect. There are actually 25 in the US, and 7 in the rest of the world, totalling 41 prints.
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> see the 35 mm trailer for reference
The article makes heavy use of referring to scans of trailers to show what colours, grain, sharpness, etc. looked like. This is quite problematic, because you are replying on a scan done by someone on the Internet to accurately depict what something looked like in a commercial cinema. Now, I am not a colour scientist (far from it!), but I am a motion picture film hobbyist and so can speak a bit about some of the potential issues.
When projected in a movie theatre, light is generated by a short-arc xenon lamp. This has a very particular output light spectrum, and the entire movie process is calibrated and designed to work with this. The reflectors (mirrors) in the lamphouse are tuned to it, the films are colour graded for it, and then the film recorders (cameras) are calibrated knowing that this will be how it is shown.
When a film is scanned, it is not lit by a xenon short-arc lamp, instead various other illumination methods are used depending on the scanner. CRTs and LEDs are common. Commercial scanners are, on the whole, designed to scan negative film. It's where the money is - and so they are setup to work with that, which is very different to positive movie release film stock. Scanners therefore have different profiles to try and capture the different film stocks, but in general, today's workflow involves scanning something in, and then colour correcting post-scan, to meet an artist's expectations/desires.
Scanning and accurately capturing what is on a piece of film is something that is really quite challenging, and not something that any commercial scanner today does, or claims to do.
The YouTube channels referenced are FT Depot, and 35mm Movie Trailers Scans. FT Depot uses a Lasergraphics 6.5K HDR scanner, which is a quite high end one today. It does have profiles for individual film stocks, so you can set that and then get a good scan, but even the sales brochure of it says:
> Many common negative film types are carefully characterized at Lasergraphics to allow our scanning software to compensate for variation. The result is more accurate color reproduction and less time spent color grading.
Note that it says that less time is spent colour grading - it is still not expected that it will accurately capture exactly what was on the film. It also specifies negative, I don't know whether it has positive stock profiles as I am not lucky enough to have worked with one - for this, I will assume it does.
The "scanner" used by 35mm Movie Trailers Scans is a DIY, homemade film scanner that (I think, at least the last time I spoke to them) uses an IMX-183 sensor. They have both a colour sensor and a monochrome sensor, I am not sure what was used to capture the scans linked in the video. Regardless of what was used, in such a scanner that doesn't have the benefit of film stock profiles, etc. there is no way to create a scan that accurately captures what was on the film, without some serious calibration and processing which isn't being done here. At best, you can make a scan, and then manually adjust it by eye afterwards to what you think looks good, or what you think the film looks like, but without doing this on a colour calibrated display with the original projected side-by-side for reference, this is not going to be that close to what it actually looked like.
Now, I don't want to come off as bashing a DIY scanner - I have made one too, and they are great! I love seeing the scans from them, especially old adverts, logos, snipes, etc. that aren't available anywhere else. But, it is not controversial at all to say that this is not colour calibrated in any way, and in no way reflects what one actually saw in a cinema when that trailer was projected.
All this is to say that statements like the following in the article are pretty misleading - as the differences may not be attributable to the direct-digital-release process at all, and could just be that a camera white balance was set wrong, or some post processing to what "looked good" came out different to the original:
> At times, especially in the colors, they’re almost unrecognizable
> Compared to the theatrical release, the look had changed. It was sharp and grainless, and the colors were kind of different
I don't disagree with the premise of the article - recording an image to film, and then scanning it in for a release _will_ result in a different look to doing a direct-digital workflow. That's why major Hollywood films spend money recording and scanning film to get the "film look" (although that's another can of worms!). It's just not an accurate comparison to put two images side by side, when one is of a trailer scan of unknown accuracy.
I'm lucky enough to own two working ThunderScans now (and one third one that I needed the software driver from). They work exactly as advertised, and it's a joy to see them zip across the page, digitising line by line.
The software by Hertzfeld is another joy to use. The scrolling, which Hertzfeld calls "inertial scrolling" in that article, is now familiar to us all who have used touchscreen devices. It's funny to think that the feature that wowed so many at the 2007 iPhone launch actually existed all the way back in 1984, designed by one of the key creators of the Macintosh.
I wish there were more creative hacks like this - I just know that if a company tried to do something similar today, the printer manufacturer would instantly roll out an update to break this functionality.
What sort of tactics did you use to convince them? Maybe I can apply them to where I work too...
Really random follow up question - there's a How to Train Your Dragon advert that I assume played before the first film in cinemas, advertising the cinema's popcorn and other concessions, but the only two copies on YouTube are in really terrible quality. (one in English https://www.youtube.com/watch?v=f37fI14Ne0I, the other in Finnish I think https://www.youtube.com/watch?v=W0Hr4mD3G1Q). I really really want a high quality version of this, and I'm wondering if you know of anyone at DreamWorks who I can contact about this? I've tried tweeting at a couple of people but unsurprisingly heard nothing back, so I'm maybe looking for someone in marketing?
It still works, and I’m going to take it to EMF Camp this weekend and send a fax using it!
GitHub did this with its Archive Program https://archiveprogram.github.com/, and Piql https://www.piql.com/ is a company that specialise in doing this. They're the company that created the Cinevator, a high speed data to film transfer machine that was originally used for creating film prints, but since film is kinda dead these days, they've pivoted to archival storage.
There are 3 blocks every 128 on the film that contain the software update (and/or other data channels, or are unused). They're also used for something called the "Splice cache" which I can discuss if you want. The rest are the audio blocks.
As far as I'm aware, Dolby only used this once - to update from what they called version EC9 to EC11. I've also heard that it didn't work well with the DA10 - their first processor - and this may be part of the reason.
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Oh, a topic I know a bit about!
To add a few things onto the stuff mentioned in the article: - A lot of places mention Dolby Digital on film being AC3 encoded. This is sadly not true - ish. Dolby were developing AC3 for film and other applications, but the version that ended up going on film isn't quite AC3 - although I suspect it's very close. To quote someone at Dolby:
> The audio coding used is actually a pre-cursor of what became AC3, and in fact, two different versions of the codec were used during the lifetime of Dolby Digital on film. We referred internally to these as EC9 and EC11. I don’t remember the exact characteristics of these codecs but unfortunately they are not compatible with AC3
- The article mentions Reed-Solomon encoding being used - this is indeed the case, but more specifically a concatenated code meaning that two Reed-Soloman instances are applied one after the other. However because nothing is nice and simple here, some of the bits are only protected by one of the R-S layers and not both, but I'm not sure which at the moment.
- The article questions how the bytes are stored - this is actually mentioned in the patent. The bytes are arranged in 2x4 groups, ie 2 horizontal, 4 vertical, and therefore each block is 38 bytes wide, and 19 bytes high. Interestingly the picture in the article is rotated - you can tell by the Dolby logo being the wrong way round.
- Something not mentioned in the article or the patent - before the Reed-Solomon decoding is applied, all the bits are XORed against a constant in order to break up large black or white areas which would be hard to detect. Because the same value is used during encoding as decoding, the original data is recovered. Sadly, I don't know what this constant value is.
I would love there to be a open source decoder for the Dolby Digital on film, but at the moment I'm at the limit of my knowledge on AC3 and audio signal processing. If anyone knows more, or wants to help, I'd be delighted! You can reach me on email `[email protected]` or discord `davidferguson#2018`