Film-Tech Forum ARCHIVE: IMS2000 not outputting 7.1

This is topic IMS2000 not outputting 7.1 in forum Digital Cinema Forum at Film-Tech Forum ARCHIVE.

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Posted by Chad Bateman (Member # 6006) on 10-17-2018, 03:54 PM:

Has anyone been able to get a IMS2000 to play 5.1 or 7.1 through the HDMI port without changing inputs on the processor? I have a IMS2000 with a CP750 which with all the server content works fine but if I run a Blu-ray, computer, or any other source (even with PCM)I can only get L/R.

Posted by Harold Hallikainen (Member # 5405) on 10-17-2018, 04:10 PM:

Sounds like a aetting in the Blu ray player.

Posted by Leo Enticknap (Member # 534) on 10-17-2018, 04:20 PM:

Have you tried multiple HDMI sources, and/or been able to play 7.1 from the player that is giving you the problem into another audio processor?

Posted by Chad Bateman (Member # 6006) on 10-17-2018, 04:52 PM:

it's a 8-plex. 2 have ATMOS with 850's. I have tried 2 different Blu-rays and 3 different laptops. I have tried to even use a scaler to modify the sound setting in all case I have tried every sound setting. (dolby, DTS digital, with or without PCM) manual says any PCM source should work through the HDMI port.

Posted by Leo Enticknap (Member # 534) on 10-17-2018, 05:09 PM:

Check the mix settings for the HDMI preset on your 850. It could be downmixing the HDMI audio to 2.0. If it is, you'll see an arrow pointing diagonally from 7.1 on the left to 2Ch on the right.

Posted by Chad Bateman (Member # 6006) on 10-17-2018, 05:31 PM:

I will look at that for the 850's and let you know. Now any ideas for the 750's? I know I could just use Dig 4 with prologic but I would really like to stay on digital 1 so the customer can stay on the same channel for alt content.

Posted by Harold Hallikainen (Member # 5405) on 10-17-2018, 05:33 PM:

I'd really look at the BLU ray player. On AES/EBU input, it just does eq and delay (unless you're decoding Dolby Digital). I expect the IMB to just pass through whatever it gets from the Blu ray player (converting the audio on the HDMI to AES3 to drive the CP750).

Good luck!

Harold

Posted by Steve Guttag (Member # 268) on 10-17-2018, 09:31 PM:

With HDMI, you enter the world of EDID and the havoc it can cause too. If the IMS is only calling for 2-channel, that is all that the source will deliver too. Remember too, Dolby products don't support DTS, despite DTS being the overwhelming majority of Blu-ray encoding.

If your Blu-ray player is capable of decoding the audio and outputting AES on the HDMI cable, then the IMS should be able to pass that through, channel for channel.

This problem is not unique to any particular brand of IMB/IMS type server too and it gets all the more complicated when one uses channel mapping. For instance, the ICMP (Barco) will output 7.1's Lrs/Rrs channels on 7 and 8 regardless of how the DCP is configured. So, if you DON'T remap DCP 7.1 from channels 11/12 to 7/8 those two channels will not be present. I wish ALL of the IMS/IMB manufacturers would realize that for HDMI sources, if there is audio on pair-4 to have it follow the mapping of the Lrs/Rrs of the DCP and output on the same channels.

Fortunately, more and more sound processors have an HDMI decoder available (QSC, Datasat) that will handle DTS, Dolby or LPCM and don't have the political issues of having to shun one very popular format. Note too, there is a semi-expensive, yet professional approach with Crestron. Their HD-XSP decoder supports Dolby, DTS and LPCM and one can configure it to automatically decode various 2-channel formats in a specified way (e.g. Pro-Logic).

Circling back to EDID...remember too that HDMI is a least-common-denominator format. So if you have any other devices (e.g. a confidence monitor for cuing) it can "pollute" the EDID table and only call for 2-channel stereo if that is all it knows. Many professional broadcast and AV components only call for stereo audio. Cinema and Home equipment are the ones that call for multi-channel. Extron is a company that seems to "get it" and have multi-channel audio as an option and preserve the various high-quality multichannel digital audio EDID.