Film-Tech Forum ARCHIVE: CP850 and Alternate Content

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Posted by Steve Guttag (Member # 268) on 01-16-2014, 05:19 PM:

Those of you with the Dolby CP850 (Atmos) sound processor...how are you all handling Alternate content from sources like BluRays? I ask because Dolby did not see fit to include a multi-channel analog input on this unit. The vast majority of the BluRays commercially authored use the DTS audio encoding (DTS Master Audio)...Dolby, as you can expect, does not have a DTS decoder on-board so this leaves one with the choice...do you dumb down the BluRay audio to stereo so the CP850 can handle it or do you come up with a means to provide LPCM 7.1 audio via HDMI?

Since the theatres likely to have the CP850s are going to be the primo ones...one would hope that they are not using plain stereo source material when high-bandwidth multi-channel audio is available. Now I can come up with a means to decode the HDMI audio to analog just fine (from Dolby or DTS or straight LPCM)...but then one has to get it back to either HDMI in digital form or into just AES form so the CP850 can "decode" it and send it to the proper channels.

Good AES switchers are not cheap nor are good analog-to-digital converters that wont effectively ruin the high-quality audio that you are starting with.

Those of you that have the CP850...what are you all doing for alternative content that is encoded with DTS?

Posted by Carsten Kurz (Member # 5396) on 01-16-2014, 05:28 PM:

First of all, I would guess that most ATMOS enabled auditoriums are probably kept busy playing high-profile DCP content, thus alternative content should be a rare species on existing CP850s.

Second, if you shell out 150.000US$+ for an ATMOS installation, I guess it's no big problem to buy a BluRay Player with discrete multichannel LPCM output over HDMI so the CP850 will accept decoded DTS-HD and the like. I think most current Sonys will do that if the HDMI sink does not identify to support native HD formats.

- Carsten

Posted by Steve Guttag (Member # 268) on 01-16-2014, 07:32 PM:

Cartsen,

We have one venue that is looking to go all Atmos and we also have a screening room or two that are planning on it...so alternative content could be in many forms, including BluRay or Cable or what have you. I generally don't like to have each source device have the overhead of overcoming another device...whatever is THE HDMI audio decoder should be able to handle all sources and then send the audio on its way. That works for us in say a CP750 house where we have the multichannel audio in...but in a CP850 theatre...this will be a problem.

Now that Oppo is able to keep its Icons off the screen (and the screen saver)...we are starting to head in that direction...certainly, as far as BluRay and DVDs are concerned, we have many audio decoding options there...but that will be but one source.

Posted by Anders Nordentoft-Madsen (Member # 3334) on 01-17-2014, 04:54 PM:

At our one Atmos screen we use the Vantage box to switch between the "old" processor (Datasat AP20) and the CP850.

Posted by Marcel Birgelen (Member # 6801) on 01-17-2014, 06:46 PM:

quote: Steve Guttag
but then one has to get it back to either HDMI in digital form or into just AES form so the CP850 can "decode" it and send it to the proper channels.

I've yet to see a box that can encode multichannel analog audio back to HDMI. The other way around, there's plenty of choice. It doesn't really sound like rocket science, but there's probably just a very limited market for those kind of converters. If you happen to find one, I'd be rather interested too [Wink]

.

If you want to go from multichannel analog to AES/EBU, you could use something like this. Not exactly cheap, but should get the job done.

But since the CP850 has just one single multichannel AES input, which you probably want to keep for backward compatibility with 5.1/7.1 LPCM DCP content, you will still need something like a multichannel AES switcher or stack multiple AES switchers which hopefully have some sensible automation interface.

In any case, if you need anything more than stereo, it best supports multi-channel LPCM over HDMI or it will get rather messy, unless a company like Geffen releases a scaler/switcher with the CP850 in mind.