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Topic: Dolby DSS200 HI/VI
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Leo Enticknap
Film God
Posts: 7474
From: Loma Linda, CA
Registered: Jul 2000
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posted 06-22-2018 05:05 PM
It depends on what media block (cat862 or cat745 IMB?) you are using, and how its audio output is connected to your audio processor.
Keep in mind two things:
1. The DSS200 does not let you route the audio channels in software, so the HI and VI are going to be coming out on 7 and 8, unless you're using a customized cable to cross them over in the physical connection to the CP750. Unlike with a Doremi, GDC, etc., you can't change the software channel routing to make life easier at the other end.
2. The CP750 can only process 8 channels of incoming AES audio, meaning that it can't process 7.1 audio and HI/VI simultaneously. You can either have 5.1 plus HI and VI, or 7.1 without. Incidentally, and with apologies for the shameless plug, we (MiT) offer a workaround for this, in the form of a DB25 to RJ45 adapter which is pinned for 7.1, but with a pigtail wire with an RCA or BNC connector on the end of it, which gives you the HI and VI channels to go straight into an external DAC, bypassing the CP750 altogether. This enables you to have both HI and VI, plus 7.1 audio, in a CP750-based system.
Here are some things I would check.
1 - Are you using a DB25 to RJ45 adapter to take the sound out of a cat862 media block? If so, is that adapter wired to send 7 and 8 into Ethernet cable A, pair 4? If it's wired to route those channels somewhere else, that will give you a problem. For example, there are some adapters out there that cross 7 and 8 over to 15 and 16, because the audio processor can only use HI and VI on 15 and 16.
2 - Are you using a RJ45 to DB25 adapter on the input of the CP750? Again, the same thing applies. The bottom line is that you need to be sure that 7 and 8 coming out of the media block correspond to 7 and 8 going into the CP750. Check the pinouts of both the media block you're using and the CP750's AES input against how your connection is wired.
Here are the pinouts for the CP750's DB25 AES input connector:
3. Are you playing 7.1 audio, using a cable that crosses channels 11 and 12 coming out of the media block to 7 and 8 going into the CP750? If so, you can't play the HI and VI tracks. In order to do so, you'll have to lose 7.1 capability, and use a regular cable that doesn't cross over these two channels.
4 Check the digital input 1 configuration in the CP750 setup utility, to be sure that it is set for 5.1, and that the HI and VI channels are routed to the BNC AES out correctly.
5 - I know that this is obvious, but check that the content you're using to test actually has HI and VI tracks on it. There is an SMPTE test DCP (I think you can get it from ISDCF's website) that channel IDs everything, including these tracks.
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Leo Enticknap
Film God
Posts: 7474
From: Loma Linda, CA
Registered: Jul 2000
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posted 06-22-2018 09:34 PM
Yes, there are Odyssey options as well.
quote: Steve Guttag
First, the CP750 can handle 10-channels of AES at once.
OK, poor wording. It can't handle 10 channels of AES through the DB25 input, which is only wired for eight. So we're back to needing a way of breaking out 7 and 8 before they reach the CP750. And if you're going to do that, you might as well send them straight to wherever they're going (e.g. a Fidelio transmitter, or a USL IR system via a DAC). I can't think of any good reason to pass them through the 750 if you have to break them out at the source anyways. It's just another failure point in the signal path.
quote: Steve Guttag
As for your shameless plug...if the server is outputting AES3 (balanced 110-Ohm 4-5Vp-p)...does your RCA/Coax adapter have a transformer in line to at least get the impedance right? How about the pad to knock it down to about 1Vp-p?.
I don't know (I've never taken one apart and looked inside it): all I do know is that I've installed around 20 of them, both with HI/VI transmitters that take a direct AES input, and with DACs, and they work without issue.
As for channel routing in software (either at the media block end or the audio processor end), I agree that the risk is that those settings will be lost, either by a software update, the unit having to be replaced and the installer didn't make a setting backup, etc. etc., and that reconstructing them will be difficult, because it will probably be done by someone other than the person who did the initial installation.
However, for media block > processor combos that can't just take a pin-to-pin connection, a customized cable (or adapter) that crosses over pins has drawbacks, too. The advantage is that it's idiot- and accident-proof, as long as the hardware configuration stays the same. The disadvantage is that if you replace or modify any aspect of the hardware installation, you're going to need a new customized cable. I hit this issue recently when replacing servers in an installation with a CP650, HI/VI breakouts, CCAP and DBox breakouts. The installation as I found it consisted of multiple adapters, dongles, and Odyssey cards. I had to tear the whole lot out and start over.
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Steve Guttag
We forgot the crackers Gromit!!!
Posts: 12814
From: Annapolis, MD
Registered: Dec 1999
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posted 06-23-2018 08:03 AM
Leo, your statement was worse than that. It more than implied that one would need to purchase an external D/A converter.
quote: Leo Enticknap
...straight into an external DAC, bypassing the CP750 altogether. This enables you to have both HI and VI, plus 7.1 audio, in a CP750-based system.
At no point was it even remotely qualified that the 4xAES connector (DB25), which can, by definition/label/or otherwise, can only handle 4 pairs of AES at once but that one may also use the Digital 2 input simultaneously.
At the best, your information was incomplete, at the worst, misleading.
You REALLY can't think of a good reason to use the CP750 as your D/A converter for HI/VI? Really? Not one reason? Here, let me throw this out, how about it is FREE, at that point. No external D/A converters, complete with tally LED that you have AES on the HI/VI cable.
If you are using the Fidelio, the Fidelio way (something I'm NOT a fan of), then they have already got it figured out for you with their adapter that will work with either DB25 or RJ45 (you supply your own cables though, they just supply the boxes) such that the only HI you get is from the track on the DCP and screw everything else.
Or, you send them through the CP750 Digital 2, pick up HI on the HI output of the CP750, since MOST people will want the HI information from ALL sources and VI will be on AUX-8 out. If you have the QSC/USL system, you are ready, at that point to send them to the modulator/emitter. If you have the Fidelio, then you have an A/D process to go through because, well, Fidelio didn't think that they needed to handle HI for anything but DCPs that were so encoded.
And note, even if you want to send the AES audio straight to Fidelio, it is a 75-Ohm 1Vp-p system (AES3-id) but you have 110-Ohm 4Vp-p (AES3).
So you jam that into the BNC and it worked...great! Still wrong. You have no idea what that signal looks like and it is going to vary based on the lengths of cables because that is how transmission theory and intrinsic impedances work.
See Rane Note 149
https://www.rane.com/note149.html
As for cabling to the equipment installed. It takes an actual change in model of equipment, at either end for the potential of the cable to no longer be valid. So is there really a time when hardware is changed (to different make/model) where cable changes shouldn't be anticipated?
And yes, those that use an abundance of dongles tend to get a system that gets unwieldy pretty fast. We generally make our own cables so having the ends have the signals we want normally isn't a problem. For proper AES3 cables (true twisted pair/shielded) we would run 8-pair snake and connect up the pairs needed for the system. If the processor is a true 16-channel one like the QSC DCP200/300 then all 16 channels are landed and the sound processor's formats are set up to get the desired channels. Everything is 1:1. For a processor like the CP750, the 4xAES would be wired for 7.1 and pair 4 would go to Digital 2, via an adapter. Now, if the theatre is 5.1 then it is a straight cable pin-for-pin.
A mistake I think QSC makes on their DCP100 and DPM models is to designate the second RJ45 as the HI/VI input (and on pair 4 only). It makes more sense to me to make the first RJ45 handle 5.1 with HI/VI. So all of the 5.1 theatres would just need a straight up Ethernet cable and no channel re-routing would be needed. If you have 7.1 then run the second Ethernet cable and have it pick off pair 2 for 7.1. Then, no custom cables and everything is straight forward. I guess Odyssey wouldn't have such a good business if designers really thought out their product installations well. The Odyssey guys are great so more power to them.
The vast majority of our new systems are built around 16-channel input processors so it is a non-issue for me too.
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