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» Film-Tech Forum   » Operations   » Digital Cinema Forum   » Audio Description and 7.1 Sound (Page 1)

 
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Author Topic: Audio Description and 7.1 Sound
Michael Sharples
Film Handler

Posts: 12
From: Leeds, West Yorkshire, England
Registered: Jun 2015


 - posted 06-20-2015 01:57 PM      Profile for Michael Sharples   Author's Homepage   Email Michael Sharples   Send New Private Message       Edit/Delete Post 
We can currently screen DCP films in 5.1 with audio description but not in 7.1. I take it this is because the channels carrying the AD data in 5.1 are used to carry the left and right rear data in 7.1. I am also assuming there is a fix for this, if so what is the nature of the fix and how easy is it to do?
We have a CP750 processor.

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Stephan Shelley
Jedi Master Film Handler

Posts: 533
From: castro valley, CA, usa
Registered: Nov 2014


 - posted 06-20-2015 02:48 PM      Profile for Stephan Shelley   Email Stephan Shelley   Send New Private Message       Edit/Delete Post 
Actually the rear surround channels are on 11 & 12. You have a board or cable that puts 11 & 12 on the 7 & 8 input on the CP750. Both Odyssey and Ultra Stereo have solutions to breakout the HI/VI and move channels 11 & 12 to the 7 & 8 inputs.

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Carsten Kurz
Film God

Posts: 3277
From: Cologne, NRW, Germany
Registered: Aug 2009


 - posted 06-20-2015 03:51 PM      Profile for Carsten Kurz   Email Carsten Kurz   Send New Private Message       Edit/Delete Post 
Michael - get the current CP750 manual (at least rev. 5), you will see 7.1 and HI/VI operation explained in it. It's a bit complicated as some signals are rerouted.

- Carsten

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Marco Giustini
Film God

Posts: 2496
From: Reading, UK
Registered: Nov 2007


 - posted 06-20-2015 05:55 PM      Profile for Marco Giustini   Email Marco Giustini   Send New Private Message       Edit/Delete Post 
It's weird that you have AD in 5.1 but not in 7.1. The 750 will route channel 8 to the AUX phono socket on the back, which feeds your AD device. As mentioned, the back surround channels are 11 and 12.

Main question is: is your system 7.1? If your channel 8 is properly routed, it should always be routed.

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Pete Naples
Phenomenal Film Handler

Posts: 1536
From: Dunfermline, Scotland
Registered: Feb 2001


 - posted 06-21-2015 01:32 PM      Profile for Pete Naples   Email Pete Naples   Send New Private Message       Edit/Delete Post 
I suspect whomever wired the system didn't connect CH7/8 from the server to DIG2 input on the CP750.

Run a channel check DCP with HI/VN in both modes to really see what's going on.

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Marco Giustini
Film God

Posts: 2496
From: Reading, UK
Registered: Nov 2007


 - posted 06-21-2015 02:56 PM      Profile for Marco Giustini   Email Marco Giustini   Send New Private Message       Edit/Delete Post 
Yes but... if 7/8 are still wired to 7/8 input, then you wouldn't have 7.1 out of that system.

What you say is correct but if they can hear AD in 5.1 it means that channel 8 is wired to channel 8 - which mean they cannot have 7.1!

Michael, have you ever tried running a Dolby channel ID on your system? As Pete says that will tell you the truth [Smile]

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Harold Hallikainen
Jedi Master Film Handler

Posts: 636
From: Denver, CO, USA
Registered: Aug 2009


 - posted 06-21-2015 03:11 PM      Profile for Harold Hallikainen   Author's Homepage   Email Harold Hallikainen   Send New Private Message       Edit/Delete Post 
As Pete mentions, Dolby did an interesting workaround in one of their updates. In that case, AES/EBU inputs (8 channels) get routed to 8 channels of analog out, great for 7.1. Two channels of S/PDIF on Digital Input 2 get routed to the "7/8" RCA jacks on the back of the unit. So, you need to get tracks 11 and 12 (rear surrounds) to AES inputs 7 and 8, and tracks 7/8 (HI/VI) to digital two to come out the RCA jacks.

Harold

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Marco Giustini
Film God

Posts: 2496
From: Reading, UK
Registered: Nov 2007


 - posted 06-21-2015 04:13 PM      Profile for Marco Giustini   Email Marco Giustini   Send New Private Message       Edit/Delete Post 
That's correct, of course. But if the system is 7.1 that means that channel 11/12 are routed to input 7/8 for 7.1 to work.

If AD works in 5.1, I would expect that channel 7/8 are routed somewhere - DIG2 if the system is set to 7.1.

My impression is that the system is in fact set to 5.1, channel 7/8 are routed to 7/8 which works well in 5.1. Now, can you select "Dolby 7.1" on a CP750 which has been set to 5.1 in the general settings?

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Pete Naples
Phenomenal Film Handler

Posts: 1536
From: Dunfermline, Scotland
Registered: Feb 2001


 - posted 06-22-2015 02:06 AM      Profile for Pete Naples   Email Pete Naples   Send New Private Message       Edit/Delete Post 
That's my point. I've come across countless systems where the site believes it to be 7.1 capable but actually due to input mis-wiring or processor misconfiguration, it's never playing real 7.1 [Wink]

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Marco Giustini
Film God

Posts: 2496
From: Reading, UK
Registered: Nov 2007


 - posted 06-22-2015 06:32 AM      Profile for Marco Giustini   Email Marco Giustini   Send New Private Message       Edit/Delete Post 
I'll pretend I didn't read that... [Frown]

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Pete Naples
Phenomenal Film Handler

Posts: 1536
From: Dunfermline, Scotland
Registered: Feb 2001


 - posted 06-22-2015 12:26 PM      Profile for Pete Naples   Email Pete Naples   Send New Private Message       Edit/Delete Post 
Don't. I've lost count how many '7.1' systems I've been asked to fix. The ones with 6 power channels.... The ones where HI/VN is booming out of the rear surrounds....

I could go on.

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Carsten Kurz
Film God

Posts: 3277
From: Cologne, NRW, Germany
Registered: Aug 2009


 - posted 06-22-2015 01:47 PM      Profile for Carsten Kurz   Email Carsten Kurz   Send New Private Message       Edit/Delete Post 
I'm not sure, but I think Datasat added explicit 5.1, 7.1+HI/VI signal routing patterns in one of their more recent software updates. When you had a previous 7.1 configuration and applied the software update, it somehow defaulted to a 5.1 afterwards. I you didn't check after the software update, you would think your system was still 7.1, but in fact was 5.1 with too much surround level applied, until you went in and adjusted to the proper 7.1 routing preset.

- Carsten

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Michael Sharples
Film Handler

Posts: 12
From: Leeds, West Yorkshire, England
Registered: Jun 2015


 - posted 06-25-2015 10:28 AM      Profile for Michael Sharples   Author's Homepage   Email Michael Sharples   Send New Private Message       Edit/Delete Post 
Thanks for the responses. I managed to get the audio description to work through the general settings of the CP750 software, 7/8 Aux out were disabled for the 7.1. Once i changed that to the route digital 2 option audio description was working. I will be sure to run a channel check anyway though. Thanks again

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Marco Giustini
Film God

Posts: 2496
From: Reading, UK
Registered: Nov 2007


 - posted 06-25-2015 02:48 PM      Profile for Marco Giustini   Email Marco Giustini   Send New Private Message       Edit/Delete Post 
I was not aware that that option was format dependent. As far as I know it's either enabled or disabled. Hence, your AD either works or it doesn't.

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Michael Sharples
Film Handler

Posts: 12
From: Leeds, West Yorkshire, England
Registered: Jun 2015


 - posted 06-25-2015 03:03 PM      Profile for Michael Sharples   Author's Homepage   Email Michael Sharples   Send New Private Message       Edit/Delete Post 
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