Film-Tech Forum ARCHIVE: Wrong audio tracks on HDMI input

This is topic Wrong audio tracks on HDMI input in forum Digital Cinema Forum at Film-Tech Forum ARCHIVE.

To visit this topic, use this URL:
https://ft-forum.com/ft/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=16;t=002708

Posted by Joost Vandertogt (Member # 9459) on 05-31-2016, 08:12 AM:

Hello all, I'm pretty new in this bussiness. Originally I'm a sound engineer in a theatre (in the Netherlands) and since november last year we have a DC setup in our small stage. The setup is:
Doremi DCP-server
Doremi IMB
Barco DP2k-15C
Datasat AP20

Audio from IMB to AP20 is AES.
On the IMB, there's a HDMI input, which we would like to use for viewings outside of the usual screenings. When I last connected a MacBook, the picture was fine, but there's something odd with the audio tracks. When viewing a video with 5.1 sound, the center channel was missing. When putting just audio from iTunes, the audio came on input 3 and 4 on the AP20 (center and sub).
Now my question is: what's going wrong and where can I (if possible) correct it?
Later I'll try with a DVD/Blue-ray, but we're a little busy at the moment...

If the solution is above my head, I'll ask DCinex when they come for maintenance in November.

Thanks in advance!
Kind regards Joost

Posted by Dave Macaulay (Member # 813) on 05-31-2016, 02:22 PM:

The HDMI sound processing in the IMB is mysterious, I have tried to get details from Doremi without success. Some sources give 5.1 sound and some don't. Some come out as L/R (AES pair 1) which can be decoded with ProLogic to whatever that gives (4.1?).
Apple have their own impenetrable secrets, no clue what is happening there. Try a standard DVD player with HDMI output and see what you get out of the IMB.
Generally I find it better to strip out the digital audio signal from HDMI and deal with it in an outboard processor, where non-DCP content playback is required. It just makes everything simpler especially with BluRay where there are so many audio options. If you strip out HDMI digital audio and send it to an AP20 SPDIF input you should have better results.

Posted by Sascha F. Roll (Member # 9043) on 05-31-2016, 02:28 PM:

Never had any serious issues with the HDMI audio de-embedding in the AP20. It just works. And is easy to configure.

Just connect your HDMI source to the AP20 HDMI inputs 1-4 und send the "picture" stream to your IMB and everything should work fine.

/Edit: The only thing that didn't work for me was Copying the Side Surrounds to the Back Surrounds (on a DS7.1 channel layout) when using DTS NEO6 Matrix Decoding.

Posted by Joost Vandertogt (Member # 9459) on 05-31-2016, 03:03 PM:

Thanks for the answers.

Sascha, I'm using the HDMI input on the IMB in the projector. The AP20 gets its AEB audio signal by about 35 meters of Shielded CAT6 cable, because all the amps (and AP20) are in a room with all other amps of tha hall, so using the HDMI input of the AP20 is not quite an option, because the HDMI signal has to travel the same distance back to the projector (or we have to use 2 HDMI ports on the source).

Dave, I'll soon try with an ordinary DVD-player and maybe a Windows notebook, to see if it reacts different then Mac. And offcourse I'll post my findings [Smile]

Posted by Sascha F. Roll (Member # 9043) on 05-31-2016, 03:10 PM:

Maybe this discussion here might be interesting for you as well?

http://www.film-tech.com/ubb/f16/t002689.html

Posted by Joost Vandertogt (Member # 9459) on 05-31-2016, 03:34 PM:

Yeah, I went through that post already, but thanks for the heads up!

Posted by Carsten Kurz (Member # 5396) on 05-31-2016, 07:18 PM:

Joost - the Doremi IMB is very poor in decoding most popular HDMI audio formats. I suggest you feed HDMI sources to the AP20 4/1 switcher and use a HDMI extender from there. The AP20 is the only cinema processor with all the necessary audio format decoding. Besides that, the Mac has a full audio routing feature in audio setup in the utilities folder.

- Carsten

Posted by Peter Castle (Member # 1997) on 05-31-2016, 10:07 PM:

Some time back I encountered a similar (perhaps the same) problem in making a DCP from a 6-channel quicktime movie. The six channels were in one order, while the DCP wants Windows WMA(?) order. I can't remember the workaround but I seem to recall a PC program that allowed the shuffling of the channels.

Posted by Joost Vandertogt (Member # 9459) on 08-11-2016, 07:15 AM:

Today I finally found some time to do some tests...
All without succes... Even from a DVD-player the sound wasn't routed correct from IMB to AP20. I even tried using other audio settings in Doremi (not sure if they effect the IMB or just the Doremi/DCP).
So next step is to contact the supplier, see if they know some way to get it to work correctly. If not I guess we have to spend some money to get some very good HDMI extenders...

Posted by Carsten Kurz (Member # 5396) on 08-11-2016, 11:54 AM:

Maybe you have a non-standard AES-Routing and audio routing table setup in the Doremi to the AP20.

There is actually not much to do about the HDMI-AES mapping in the Doremi, it is 1:1. Doremi has a techdoc dealing with adjusting the mapping for different SDI and HDMI mappings on a per-CPL basis. I don't know if you have access to

http://support.doremitechno.org/index.php/faq/digital-cinema-player/set-up/499-imb-audio-channel-3-4-swapped-when-switching-sdi-to-hdmi

If not, pm me, and I will help you out.

You'd certainly be better of feeding the HDMI to the AP20 directly. Put some money on the HDMI extender, but you will have no HDMI/audio trouble afterwards, no matter what BluRay player you connect or what disc you play. You WILL certainly have trouble when you keep feeding the audio to the IMB HDMI input.

- Carsten

Posted by Marco Giustini (Member # 4544) on 08-11-2016, 01:59 PM:

Joost,

what Carsten said: take the HDMI to the AP20 *FIRST*, then to the IMB.

The AP20 will take care of the sound just fine.

Posted by Joost Vandertogt (Member # 9459) on 08-11-2016, 02:07 PM:

Hi Carsten,
Thanx for the link. Unfortunately I do not have access to that site...

Posted by Carsten Kurz (Member # 5396) on 08-11-2016, 02:47 PM:

Check your profile for pm...

- Carsten

Posted by Joost Vandertogt (Member # 9459) on 08-11-2016, 02:53 PM:

Thanx a lot, I'll try next week and let you know the result!

Posted by Joost Vandertogt (Member # 9459) on 08-15-2016, 03:01 AM:

Just tried with the CPL, even after rebooting the whole set-up a couple of times no result, so I'll contact the supplier, hope they can help with it, or just go with the HDMI-extender sollution...
Thanx fot the help though

Posted by Joost Vandertogt (Member # 9459) on 08-15-2016, 10:22 AM:

Update: We had a Konig single UTP HDMI extender on stock, tried with MacBook at the AP20 and extender to projector. With audio output at HDMI Decrypted the audio was routed correctly! So I just ordered one more so we can place the HDMI source at other locations than directly next to the AP20 [Smile]

Posted by Steve Guttag (Member # 268) on 08-15-2016, 12:56 PM:

Carsten,

So I see the channel mapping thing you linked to and it is interesting. I presume that it only works if you haven't channel mapped the system.

Posted by Carsten Kurz (Member # 5396) on 08-16-2016, 06:31 PM:

As far as I understand, it is meant to adjust channel mapping for live transmissions, as such for it to work, you would need to create a LiveEvent, and then assign that mapping to the 'live' CPL and play it? There doesn't seem to be a way to remap HDMI audio globally.

- Carsten

Posted by Steve Guttag (Member # 268) on 08-17-2016, 06:30 AM:

I think it works for ANY CPL...not just Live. I gave it a look and from Content Manager, you can go to any CPL and set up its unique channel mapping.

Posted by Carsten Kurz (Member # 5396) on 08-17-2016, 08:42 AM:

That's right, it does work for any CPL (type), as you can assign a mapping to any CPL present on the server. But to have an effect on HDMI->AES, you need to assign the mapping to a live event CPL with HDMI referenced as the source.

- Carsten

Posted by Steve Guttag (Member # 268) on 08-17-2016, 09:24 AM:

But does this work even if one has assigned channel mapping via the control panel?

Posted by Carsten Kurz (Member # 5396) on 08-17-2016, 10:53 AM:

Yes, there is a global mapping which is used when no per-CPL mapping is applied (which is 'always' for most systems, I guess) . But if AES/internal and IMB/HDMI channel assignment is different, you ruin the DCI channel assignment when trying to adjust for HDMI.

The per CPL mapping was probably introduced for SMPTE DCP dynamic channel routing. We'll see if that will ever become a practical reality...

I have no Doremi IMB system in daily use, so I can't check into this on a short term.

- Carsten