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2017-06-17, 09:38 PM
(This post was last modified: 2017-06-18, 02:09 AM by dvdmike.)
(2015-07-16, 08:06 PM)PDB Wrote: (2015-07-16, 03:44 PM)nafroe Wrote: I had no idea about all of that... Thanks PDB!
Any ideas on how one might go about trying to track down DCPs? I know there's the DCP for Back to the Future "out there..." Anyone know where that one came from?
DTS-X... I had no idea they were re-entering theaters! I read a bit about it and it seems pretty cool!
I'm not the expert so take what I say with a grain of salt.
You can't do anything with the any DCPs files (the one you want is called MXF). DCP files are sent to theaters on hard drive (sometimes satellite) and then uploaded to a local server (colorfully called ingesting). If you knew someone at a theater you could probably get a copy but those files but they would be useless to you because of the copy protection. Even on the server you can't play the files. The movie company have to deliver the keys before the movie can be played. The keys unlocks the files to be played by a specific projector at specific times in AES encryption (can't remember the bit size). The DCP projector actually contain a hardened box inside it that contains the decyrpting electronics. Tampering with that could invalidate the projector and the movie studio won't issue keys for it. So you are out hundred of thousands of dollars if you tamper with it, no business owner is going to do that. If you were super rich and bought a DCP projector, it normally will not included the hardware for key detection.
The exception is trailers. Often movie companies don't bother with encrypting the trailers. After all those are just ads. But on the other hand, Imax does encrypt their trailers. That's why the IMAX Star Wars VII trailer never (I think) made the rounds with its unique aspect ratio for the Falcon scene. Regardless, in some spots in the wilds of the net you can find trailer DCP files.
So the question is what about BTTF? Some said it was just a HD master used for the BDs while other said it was from a non-encrypted DCP. The current thinking is that it is the later. Mostly since someone posted some of the original 2K files (which I would love to get). They where clearly not the same as the 1080p files passed around. So this is where the story has a little conjecture. Some people have said that the movie companies didn't bother encrypting older films with keys. I guess either laziness, money saving and/or the thought that no one would want to bootleg an older film (boy were they wrong). So in the earlier digital projection days a lot of old films were not encrypted. That doesn't happen anymore, maybe because of BTTF or maybe someone just wised up. BTTF DCP started on an invite only site where we think it was "ripped" by a projectionist who noticed there was no protection and slowly made its way into the wild.
If you could get the files decrypted, what would you see? This is the cool part. The MXF file in nothing but a container for a bunch of picture files and PCM sound files. The DCP is not a video file but in fact thousands of jpeg2000 pictures files. So in a lot of ways similar to old 35mm projection, its just showing one picture at a time. The sound is just PCM in 5.1 or 7.1 configuration (Atmos being different). The size of those files start in the hundreds of gigs and moves up from there. It doubles for 3D and 48Hz. So the Hobbit in 3D, 48Hz was said to be a huge file.
Back to DTS. In the late 2000s, DTS saw the writing was on the wall. That 35mm film was on the way out so they sold their theatrical business to Datasat. Datasat is basically a caretaker, running what's left of the DTS business (they do other things, I'm just reference only the DTS business). DTS itself became an only home sound business. They did very well on BD because they offed their encoders for free whereas Dolby charged fees.
Meanwhile, Dolby was effectively pushed out of the theatrical business also. You don't need Dolby compression/NR if your soundtrack is in (zero licensing fee) PCM. So they decided to come up with a new system they could make money off in theaters. The answer was Atmos. Atmos, to simplify, takes the traditional channel system (5.1/7.1) and adds an object layer. That's a whole technical discussion for another time but object based sound system has been a dream for sound engineers for awhile now.
DTS was working on their own object based system for the home when SMPTE (Society of Motion Picture and Televsion Engineers) put out a call for a universal object sound system to be incorporated into the next revision of the DCP standards. Dolby proposed Atmos. DTS seeing a chance aligned with a bunch of other companies and created the MDA (Multi-Dimensional Audio) group. There a lot of difference between the two but MDA is basically DTS version of DTS-X for theaters (Theatrical and home Atmos vary also).
Anyway I went long, sorry. I love talking about this crap.
I thought BTTF it was decided it wasn't a DCP?
Some DCPs got uploaded but no-one is seeding
Dunkirk may have a datasat disc yet.
With audio I want a way to rip CDS and SddS.
Edit:
Yep
https://s24.postimg.cc/51z00hihh/Screens...010811.png
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The only option for 70mm is DTS discs. So if they no loger produce any, then there will be no audio playback since mag striping was discontinued long ago.
I'm sure they will still do it for special circumstances. I don't know of a single theater outside of LA or Europe hat is even capable of playing back Mag prints let alone 70mm six track mag.
IMAX iirc has their own weird formatting but used essentially a variant of DTS discs for film prints.
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(2017-06-17, 09:38 PM)dvdmike Wrote: I thought BTTF it was decided it wasn't a DCP?
Some DCPs got uploaded but no-one is seeding
Dunkirk may have a datasat disc yet.
With audio I want a way to rip CDS and SddS.
Edit:
Yep
https://s24.postimg.cc/51z00hihh/Screens...010811.png
Thanks for the link dvdmike, glad to see that they are still working the 70mm releases.
The DCP argument is in another thread, where people were confirming it was a DCP.
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2018-11-29, 12:33 AM
(This post was last modified: 2018-11-29, 12:34 AM by schorman.)
Some discussion on the source forge page for the Foobar DTS (APT-X100) decoder suggests that the newer DataSat discs may be in in the same .AUD format as the older DTS discs.
https://sourceforge.net/p/dvdadecoder/bugs/15/
Also, The decoder has been updated to work with the 6 track and 8 track "Special Venue" formats.
Hopefully the DataSat discs for Force Awakens turn up at some point.
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(2018-11-29, 12:33 AM)schorman Wrote: Some discussion on the source forge page for the Foobar DTS (APT-X100) decoder suggests that the newer DataSat discs may be in in the same .AUD format as the older DTS discs.
https://sourceforge.net/p/dvdadecoder/bugs/15/
Also, The decoder has been updated to work with the 6 track and 8 track "Special Venue" formats.
Hopefully the DataSat discs for Force Awakens turn up at some point.
I did notice the update. Weirdly, it now only converts the normal 5 channel DTS discs to 5 channels. And before you say that sounds like a weird statement to make, the old version automatically extracted the LFE from the rear channels afaik, the way it is supposed to be.
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2018-11-29, 08:59 PM
(This post was last modified: 2018-11-29, 08:59 PM by schorman.)
That may be a good thing, actually. The two issues I ran into with decoding the DTS cinema discs were that the winamp decoder introduces audible artifacts in the Right and Right Surround channels. The foobar decoder does not have this issue, and is therefore preferable. However, the foobar decoder automatically separates the LFE and surround channels, but unfortunately the levels for those channels do not seem to be accurate. For instance, DTS documents suggest that the surround channels should be attenuated by 3dB and the LFE track needs some amount of gain applied (The amount is dependent on when the film was released, and I'm not sure it's been established exactly how much should be applied). The foobar decoder does not attenuate or apply gain to any of the channels, it just separates them by applying low and high pass filters. As far as the crossover, I'll just say I'm not sure it's accurate to the DTS specs provided in their white paper.
Anyway, the newer decoder may allow us to avoid the audible glitches of the winamp decoder and still decode the LFE and surround channels in software, thus avoiding the potentially inaccurate low and high pass filtering being done by the older decoder. As far as I'm aware, there's not a big need to use the decoder for real-time playback, so while it's nice to have the LFE and surround channels split, I'd rather do that in software for better results.
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Good stuff to read. Thanks schorman.
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(2018-11-29, 08:59 PM)schorman Wrote: That may be a good thing, actually. The two issues I ran into with decoding the DTS cinema discs were that the winamp decoder introduces audible artifacts in the Right and Right Surround channels. The foobar decoder does not have this issue, and is therefore preferable. However, the foobar decoder automatically separates the LFE and surround channels, but unfortunately the levels for those channels do not seem to be accurate. For instance, DTS documents suggest that the surround channels should be attenuated by 3dB and the LFE track needs some amount of gain applied (The amount is dependent on when the film was released, and I'm not sure it's been established exactly how much should be applied). The foobar decoder does not attenuate or apply gain to any of the channels, it just separates them by applying low and high pass filters. As far as the crossover, I'll just say I'm not sure it's accurate to the DTS specs provided in their white paper.
Anyway, the newer decoder may allow us to avoid the audible glitches of the winamp decoder and still decode the LFE and surround channels in software, thus avoiding the potentially inaccurate low and high pass filtering being done by the older decoder. As far as I'm aware, there's not a big need to use the decoder for real-time playback, so while it's nice to have the LFE and surround channels split, I'd rather do that in software for better results.
Thanks for the info.
I read something like that on this site before, but I don't have the experience or knowledge to do those things properly myself without further input. Have you come up with any reproducible workflow for separating the LFE manually? Like a basic tutorial or something, ideally with free software?
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(2018-11-29, 12:33 AM)schorman Wrote: Some discussion on the source forge page for the Foobar DTS (APT-X100) decoder suggests that the newer DataSat discs may be in in the same .AUD format as the older DTS discs.
https://sourceforge.net/p/dvdadecoder/bugs/15/
Also, The decoder has been updated to work with the 6 track and 8 track "Special Venue" formats.
Hopefully the DataSat discs for Force Awakens turn up at some point.
With that being said... I'm assuming it could be theoretically used with films with a DTS-ES soundtrack?
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