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Author Topic: Toslink connection through DMA-8 Kyle Butler Film Handler Posts: 47 From: Belton, TX Registered: Jan 2010 posted 02-03-2010 08:48 PM                     We have second run shows coming up this summer. and chances are, we'll only have one lonely 35mm projector left. Details are limited at the moment, but as far as it seems, our booker will handle the licensing to play blu rays/dvd's etc. However, no solution as to what kind of setup will be used has been discussed. has anybody tryed to use the optical input on the dma8? What kind of results did you get? I could always use the external 6 channel, but that would be another piece of equipment to deal with. and has anybody found any decent SDI input switchers that have worked? it works just fine with an HDMI to Dual SDI scaler straight into the projector, but it would be a hell of a lot more convenient to not have to make disconnections nearly everyday. all of our digitals are 2500s's by the way. Ive seen similar posts like this, but none for NEC. Thanks!  |  IP: Logged Sam D. Chavez Film God Posts: 2153 From: Martinez, CA USA Registered: Aug 2003 posted 02-03-2010 10:26 PM                       I've used the Toslink several times and it works great with no hum issues that may pop up with the coax input. As to using HD SDI switchers, I don't think you can maintain Cinelink encryption using a switcher, at least not an active one. You can always use a passive patch bay.  |  IP: Logged Stephen Furley Film God Posts: 3059 From: Coulsdon, Croydon, England Registered: May 2002 posted 02-04-2010 01:59 AM                     I've used it several times from my laptop for normal two-channel PCM and once with Dolby Digital; works fine. Unlike more conventional fibres it's only intended for short distances; avoid very long cables, the one I was using was only three metres. Use decent quality cable and avoid very tight bends in it. If possible, use a single length of fibre, avoid passive couplers and cheap repeaters and fibre/co-ax converters. If you have a long distance, greater than say ten metres, try to move the equipment closer together, if you can't do that consider using co-ax, and if you have to convert between the two use a decent converter. The Toslink interface carries data in the S/Pdif format, which is exactly the same as he co-axial one. As far as the audio data are concerned it's also the same format as AES, it's only some of the metadata that differ between AES and S/Pdif, though S/Pdif doesn't have to support the highest sample rates, but often does on later equipment. The AES3id inputs on the DMA8+ (Digital 2 and 3) will also accept co-axial S/Pdif connections via a simple phono-BNC plug adapter. The 75 Ohm impedance is correct, and they will accept the S/Pdif format matadata. The Voltage is lower than for AES3id, but on short runs this won't be a problem, so you can connect players with either optical or co-ax outputs to the DMA8+; I've done both. I've used DVD with a NEC projector, NC800c, but that was with analogue component output via a Christie Cine IPM 2k to the DVI input on the projector; again, worked fine. I've no experience of Blu-ray, nor of connecting via SDI. For my laptop I used a DVI connection to the Cine IPM; again worked fine, and with 1080p material the results were surprisingly good, not far short of true digital cinema material, though this was with a very small screen. I ran a few trailers this way hen we didn't have a 35mm copy.  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 02-04-2010 08:47 AM                     Cinelink should not be affected by an SDI switcher. There are many brands for that but they are going to be expensive since SDI is a broadcast medium. Popular brands are Evertz, Harris (Leitch)...and now Extron has gotten into the market. The Barco ACS2048 is a good addition to any DCinema system to add A/V inputs to a DCinem projector using the DCinema's DVI input(s). And yes, the Toslink on the DMA8 works just fine. Steve  |  IP: Logged Sam D. Chavez Film God Posts: 2153 From: Martinez, CA USA Registered: Aug 2003 posted 02-04-2010 09:27 AM                       I went through this HD SDI issue last year while doing this Academy of Science project. We were told by Paul Zoesky and Stuart Bowling of Dolby that you cannot use an active switcher without breaking the cinelink etc. We ended up using a passive patch bay. I have not actually tried using an active switch. I believe this is prohibited by the DCI spec's. Think about it though, would it not be cool to be able to have a HD-SDI switcher that routes the cables from each server to your choice of projectors in a multiplex. You would not have to move the content and be able to switch screens in an instant. But you can't.  |  IP: Logged Carsten Kurz Film God Posts: 4340 From: Cologne, NRW, Germany Registered: Aug 2009 posted 02-04-2010 04:53 PM                     There are certainly differences between active SDI switchers. Some 'passive' ones might only use coax-relays. Some may simply replace coax relays by electronic switching, but will not touch the signal at all, so both will be transparent to CineLink Encryption. Other, more advanced switchers might actually fool around with the data in the signal. Or they will not only switch, but distribute the signal to multiple sources, which will break Cinelink as well I guess. - Carsten  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 02-05-2010 09:59 AM                     I'd be more than amazed if an active SDI switcher broke the Cinelink. The switcher is nothing more than a repeater and clocks data in, clocks it out...the signal is unchanged. Now if the SDI like is somehow being used in a bi-directional manner (not SMPTE compliant) that would be the only way an active switcher would have issues. However...the issue I could see is that you have to have the server also communicating with the right projector on the Ethernet side to keep the link. So...just switching the video (SDI) would not be sufficient, the Ethernet and subsequent MAC/IP addresses must also match. My desire to have the SDI ports on a switcher is to allow the SDI ports to be used by either DCP OR a local HD VTR (HDCAM SR). Next time the opportunity presents itself, I'll definitely give it a test. I wonder if they gave you a REASON the link would be broken. It was kinda like the 50-foot thing on the SDI cables...I always wondered WHY they needed that...I know the potential result were SDI errors but a properly designed system that follows SMPTE standards should not require a minimum length. Steve  |  IP: Logged Sam D. Chavez Film God Posts: 2153 From: Martinez, CA USA Registered: Aug 2003 posted 02-05-2010 08:43 PM                       It's all mere speculation until you try it. Steve is being logical and sometimes it's not about that. Funny, no one has tried the active switcher yet. BTW, I would never have believed the 50 Ft. cable myth until it happened to me with cables made by Lonny no less, speaking of mythical. We were getting high TI error rates in the log and I finally went in and changed to 50 Ft. cables to go all of 2 Ft. as the crow flies and the problem went away.  |  IP: Logged Brad Miller Administrator Posts: 17775 From: Plano, TX (36.2 miles NW of Rockwall) Registered: May 99 posted 02-06-2010 12:02 AM                     Geez Sam, just stop using high quality Lonny cables and go buy some short cheap crappy cables from Radio Shack.  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 02-06-2010 02:35 AM                     On the cable thing...I've done shorter than 50-foot...no problems (DSP100/DSS100 connected to a CP2000-SB). On the active switcher thing...I've had DCinema going through an active switcher (Leitch and/or Miranda) without issue...I'm trying to recall doing that with anything in recent memory where the current encryption methods are used...I don't think so...all temp setup have been direct and theatre set ups are direct...it would be in one of my "fancy" rooms that a switcher could come into play. Steve  |  IP: Logged Stephen Furley Film God Posts: 3059 From: Coulsdon, Croydon, England Registered: May 2002 posted 02-06-2010 03:45 AM                     quote: Sam D. Chavez BTW, I would never have believed the 50 Ft. cable myth until it happened to me with cables made by Lonny no less, speaking of mythical. Sam, just to clarify, which cables you're talking about; these are the HD-SDI cables from the server to the projector right? The ones at the Clocktower, the only ones I've worked with, are much shorter than that, probably about 3 metres or so. I have heard of problems with short cables on various interfaces, mainly networking ones. Many of the long-haul fibre interfaces don't work with short cables, simply due to overloading the receiver, which can be cured by simply inserting an optical attenuator; indeed, these interfaces generally need an attenuator of some value, depending on the length of the connection. Our BT connection to a site about 3 km away certainly has them at both ends. I've also heard of problems with very short Cat 6a cables on 10 Gigabit Ethernet (10G Base-T), but I'm not sure what the problem is. The old Thick (Ethernet 10 Base-5) had a minimum distance between nodes due to collision dection requirements, but I hadn't heard about SDI having problems with short cables.  |  IP: Logged Sam D. Chavez Film God Posts: 2153 From: Martinez, CA USA Registered: Aug 2003 posted 02-06-2010 10:05 AM                       It was the HD SDI cables, Steven. It was/is a problem only documented using Dolby server DSS 100 to be sure. Brad, you may be onto something about using cheap cables as the issue may have something to do with needing to attenuate the signal. It's possible the problem resolved with the DSS 200.  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 02-06-2010 10:19 AM                     My shortest cables are on a DSP100/DSS100. However, by short I mean something on the order of 25 feet. I, pretty much, use Belden cables (like in life, there are always exceptions). So I use 1694A. We keep a spool of Red and Green 1694A. Guarantees you are not going to transpose them. Steve  |  IP: Logged Brad Miller Administrator Posts: 17775 From: Plano, TX (36.2 miles NW of Rockwall) Registered: May 99 posted 02-06-2010 12:00 PM                     Sam, actually I believe it was the Dolby training course where they joked (but were serious) about the Radio Shack solution.  |  IP: Logged Geena Phillips Expert Film Handler Posts: 198 From: Norcross, GA / USA Registered: Apr 2006 posted 02-06-2010 01:16 PM                        Important to note: Toslink will not carry the uncompressed 6-channel Dolby TrueHD or DTS-HD soundtracks present on many Blu-Ray discs. The only two ways to do that are: 1) Add a processor that will decode those formats to run the HDMI to; or 2) Have a Blu-Ray player with multi-channel analog outputs to run into the external input on your normal surround processor.  |  IP: Logged

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