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Author Topic: DTS decoding Joe Redifer You need a beating today Posts: 12859 From: Denver, Colorado Registered: May 99 posted 04-07-2004 04:50 AM                        The Winamp plugin only works with recent DTS discs. Put in something old and it will not play. Put in a DTS 2 channel disc and it will not play. The plugin is guessing on the correct way to decode, unless DTS has changed something in the codec over the years.  |  IP: Logged Steve Kraus Film God Posts: 4094 From: Chicago, IL, USA Registered: May 2000 posted 04-07-2004 09:02 AM                    I will hazard a guess that at the time realtime APT-X100 decoding might only have been possible in hardware. The idea of doing it in software is based on the vastly increased computing power now available on a PC, and as you say, it's not a complex algorithim but it was probably beyond the capability of a 80386 PC. Not sure what patents or copyrights would be violated if someone used a PC-based decoder in a commercial theatre. I guess it mostly depends on the APT-X100 software itself. You're certainly not violating the copyright on the soundtrack if you're an exhibitor showing the film under license. The DTS software that is on the disks may be intended only for use on their own players but given that the disks are simply sent along with the print that could be construed as an implied license to run the software. There's no stated license, not even a shrink wrap license, for owners of bona fide boxes so not sure what would prevent its legal use on a homemade box. Not that they could not add such legalese to future disks if this ever became widespread. Then again only the booth staff would know for sure and many theatres simply advertise "digital sound" without being specific about what brand.  |  IP: Logged Bobby Henderson "Ask me about Trajan." Posts: 10973 From: Lawton, OK, USA Registered: Apr 2001 posted 04-07-2004 10:18 AM                     How often are films distributed with DTS discs accompanying every print? I have heard of theaters not equipped for DTS receiving discs. Still, my understanding is that if you want to receive the CD-ROMs with any kind of dependability you have to be in DTS' distribution list at the very least (along with the booking department in your own circuit knowing you have the DTS equipment, thus putting you down to receive the discs as well). Those issues would weigh pretty heavily on whether a theater should even try to hack out a cheap PC to play theatrical DTS. I would still expect some laws to be broken (perhaps patent violations) from using a such a setup. Advertising a show as being in DTS, but being played from a jerry-rigged PC setup may construe trademark violations. Realistically, it would be highly doubtful a single theater would get sued over such a setup. But if you had a number of theaters putting together their own PC-based DTS theatrical players, whoever came up with that WinAMP APT X100 plug-in would turn into a larger target. quote: Put in a DTS 2 channel disc and it will not play. There's 2 channel theatrical DTS discs? Hmm. Come to think of it, I do remember a Woody Allen movie released by Dreamworks (was it "Small Time Crooks"?) that was Quad Format, but I think mono on all the tracks. Still haven't seen any DVDs with DTS 2-channel, even though the DTS encoders make it possible (at two different bitrates no less, 508kb/s & 377kb/s).  |  IP: Logged Daryl C. W. O'Shea Film God Posts: 3977 From: Midland Ontario Canada (where Panavision & IMAX lenses come from) Registered: Jun 2002 posted 04-07-2004 11:07 AM                        The DTS distribution list only concerns trailer discs. Any theatre, whether or not they are capable of reproducing any sort of sound, receives discs. In fact, there are very very few times I receive a DTS print with no dics, regardless of the theatre. Apparently some theatres in the US aren't as fortunate though.  |  IP: Logged Bruce Hansen Jedi Master Film Handler Posts: 847 From: Stone Mountain, GA, USA Registered: Dec 1999 posted 04-07-2004 05:03 PM                     Look around for a used DTS6D. By the time you buy a PC, add the software, find a way to get 5 channels out of the PC, BUILD a time code reader to read the time code on the film, find a way to input the time code to the PC, find a way to have the PC sync the audio to the time code, somehow get the PC to output the control signals that your processor needs to switch to DTS, and find a way to get this all to work under windows, you could buy a used DTS player, and save money.  |  IP: Logged Joe Redifer You need a beating today Posts: 12859 From: Denver, Colorado Registered: May 99 posted 04-07-2004 05:27 PM                        Bobby, back in the day DTS couldn't make enough 6 channel units for everyone due to a drive shortage. So they started making 2 channel stereo players that would only require one drive. Many theaters actually showed Jurassic Park like this and advertised digital sound. You could only get the 6 track version at good theaters. They kept making stereo and 6 track versions of each movie fo' a long time. Perhaps more than a year. Then they dropped the stereo format and the stereo players could be upgraded to 6 track players. I think stereo DTS was probably one of the most retarded things to ever happen on the planet.  |  IP: Logged Aaron Garman Phenomenal Film Handler Posts: 1470 From: Toledo, OH USA Registered: Mar 2003 posted 04-07-2004 05:36 PM                     Were the tracks on those DTS 2 channel discs just like a PCM track on Laserdisc, and played out of two speakers, or was it basically separated by some sort of Pro Logic method? If it was just some LPCM, I'm sure it sounded fairly good. AJG  |  IP: Logged Joe Redifer You need a beating today Posts: 12859 From: Denver, Colorado Registered: May 99 posted 04-07-2004 06:12 PM                        They were compressed and then run through the Pro Logic type matrix of the cinema processor.  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 04-07-2004 07:48 PM                     Joe it wasn't a shortage of drive but the idea was to penetrate the market with a low cost version with the two channel version We had to upgrade all of them shortly after Jurasic Park  |  IP: Logged Steve Kraus Film God Posts: 4094 From: Chicago, IL, USA Registered: May 2000 posted 04-07-2004 09:59 PM                    I believe the story was that they were surprised at how poorly the 2:4 version fared in the market which was why it was dropped fairly quickly. The two channel version is sent into the CP via the solar cell inputs since a more logical entry point (post NR but pre 2:4 channel decoding) may not be available on some processors without backplane mods. So the output from the 2 channel DTS unit must be NR encoded since it will be passing through NR cards AND must be adjusted to match the slit loss correction of the pre-amp card and that's going to vary from installation to installation.  |  IP: Logged Joe Redifer You need a beating today Posts: 12859 From: Denver, Colorado Registered: May 99 posted 04-07-2004 10:10 PM                        Yup. Like I said, retarded idea.  |  IP: Logged Aaron Garman Phenomenal Film Handler Posts: 1470 From: Toledo, OH USA Registered: Mar 2003 posted 04-07-2004 11:20 PM                     Thanks for the clarification Joe. The whole thing does sound like it'd suck! AJG  |  IP: Logged Matt Zeiner Expert Film Handler Posts: 146 From: Windsor, CT USA Registered: Sep 2003 posted 04-08-2004 07:41 AM                     This could be easily accomplished with the winamp plugin, a 5.1 channel capable soundcard, some version of multitrack software (cubase SL is cheap and has SMPTE capability) and whole LOT of TIME. Decode each channel through the winamp plug out via s/pdif and into cubase via s/pdif one at a time. If you begin each pass at the same position, they will be in sync with each other. set up a send on each surround channel to an aux track with a low pass filter on it, and hi pass the surround channels. Output LCR to the appropriate channels, surrounds to the appropriate channels, and the filtered aux track to the sub. Sync can be accomplished with biphase (with the appropriate biphase to MIDI converter or a TC reader (with the appropriate SMPTE to MIDI converter). Probably would take oh, I don't know...12 hours of work to prepare for each show...  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 04-08-2004 09:33 AM                     Actually the DTS two track was suprisingly good results when properly set up the big problem was the latter was rarely done  |  IP: Logged Darryl Spicer Film God Posts: 3250 From: Lexington, KY, USA Registered: Dec 2000 posted 04-08-2004 09:51 AM                    If memory serves the DTS units that we had when Jurrasic Park opened could play either the 2 channel stereo discs or the 6 channels discs. It just depended on how you set it up. The back of the unit had outputs for both types. Luckly the theater I worked at that opened Jurrasic Park must have been one of the good ones because we played it in 6 channel sound and was one of only 11 or 12 locations in the region of the company, which was a much broader reagion at the time, to open it in DTS.  |  IP: Logged

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