Datasat AP25 - several questions

[Karim Benmachiche]

Hi all,

I know some of you here are very knowledgeable with the AP20/25. We had one installed in 2019. Overall, we are very happy with it. It's in a small arthouse cinema, where we don't have the means for DCI equipment. We mainly screen from a Windows machine (hdmi), with NeoDCP for DCPs. We also have a bluray player for the occasional school screening (hdmi), and a 16mm projector.

The software version of the AP25 is 1.05.06, with hdmi board ID HSR41-2, hdmi F/W 44 Release 43 Rev 17.

I have noticed a strange behavious with the hdmi input switch: the bluray player has no problem, we can switch back and forth to it without issue. The computer however, works only if is booted when the AP25 is set on its corresponding input. If we switch to it after boot, or switch to the bluray player and then back to the computer, the hdmi connection is lost by Windows, and a full reboot is needed. Has anyone else experienced this? Strangely enough, it is an issue that seems to be described in the latest release notes... but for another hdmi board type.

Please note I emailed ATi techsupport, but I am still waiting for a reply. I thought you people might have some ideas in the meantime Here are my questions:

1. I wanted to first try to upgrade firmware to see if it would solve the issue, but the current one is 1.05.09. Is it safe to go straight from 1.05.06 to 09? Or should I do the two intermediate ones first? (from my experience upgrading firmware on motherboard, it is always best to go version by version... by I wasn't able to select the intermediate version in the AP25 touchscreen).

2. Have you also experienced this hdmi switching issue and were you otherwise able to resolve it? I am thinking of trying to put some hdfury device between the Windows machine and the hdmi input to emulate the AP25 EDID and trick the computer into thinking the connection is not lost, but I am not sure that would work.

3. This has nothing to do with the above. I have seen a lot of talk about about matrix decoding. From what I understand, it could allow a stereo movie to be played on all - or most - speakers of our 5.1 system.
3.1 Am I understanding this corredtly, and how do I enable that for the hdmi input and only for stereo sources? (the Windows computer outputs 5.1, but we have had several 2-channel movies)
3.2 Our 16mm projector only has a mono XLR audio out, so we are using the mic input for it. It work, but I think it is sending the same channel into both L and R... can I fix that as well? not urgent at all, I don't think we are going to screen from it for another year or so, but I would rather have it setup before that

Sorry for asking here, but it's a small country, and I think we are the only ones to have a Datasat processor... it was already complicated finding one, so we don't have anyone available locally who really know the thing and could set it up for us. We all work voluntarily at this theater, I'm an IT guy, I can do a config, what I miss is knowing what to look for exactly (and I did read the manual, but I couldn't really find something applying to my situation).

Thanks!

[Marcel Birgelen]

Usually, AP20/25 upgrades with just minor version number bumps can be safely done without doing an intermediate upgrade, but you should always check the release notices to make sure your upgrade path is supported.

Many HDFury devices (Vertex, Vertex2, Integral, DR HDMI and probably some others) support "EDID spoofing" and will most likely solve your problem. We've used them in the past for exactly those kind of problems. Have you tried another computer and checked if the problem exists there too? Some graphical cards have notorious bad HDMI implementations and may not respond correctly to the AP20/25 on switchover. Sometimes, a firmware update on the machine may also alleviate problems.

You can use the DTS Neo:6 mode on your AP20/25 to enable "upconversion" of 2.0 material to "5.1" when there is no matrix-encoded surround present in the 2.0 material. While the surround quality of DTS:6 leaves a lot to be desired, it usually works fine for redirecting the dialog to the center speaker.

DTS Neo:6 will not work well on mono signals, even if you spread them over left and right. There is stuff like DTS Neural that can interpolate from mono to stereo, using neural algorithms, but this is not available on the AP20/25.

[Carsten Kurz]

The HDMI board has it's own firmware update function - it is usually NOT updated with the main software. Now, our HDMI board is probably different from yours, but, we don't have the issue you describe. The moment our AP20 is powered, it shows a solid AP20-EDID towards the PC. We can switch to any other source - be it HDMI or not, and have no issue between PC and AP20. It may, however, also depend on the display device connected to the AP20 output. You may want to use an EDID manager between PC graphics card and AP25 if you can't solve the issue otherwise. Simple EDID Managers can be bought for as little as 20€.

Neo:6, as Marcel wrote, is your option for stereo input over HDMI or Toslink/S/P-DIF. It is activated under Format Options -> Decoder Setup.
Unfortunately, you need to set your HDMI audio output to stereo in audio prefs, which will need to be reset to 5.1 or 7.1 when showing 5.1/7.1 movies. Neo:6 will not work with stereo signals over a 5.1/multichannel connection.

For XLR, you can configure mic routing into either L/R, Center, or surrounds. Center would be the better choice for mono 16mm.

I guess you just need to spend a few hours with the AP25. You could do that from a PC through VNC, which might be a little bit more convenient than standing in front of it in the booth. I suggest you set the unit to 'Expert Nav' mode (under System Setup -> Access Control). That will give you a faster access to all setup options.

- Carsten

[Karim Benmachiche]

Thanks a huge lot to you both! You have been very keen to help since the beginning I started to ask questions about renewing our system.

It's good to know you don't have an issue with hdmi on your PC, it means it should be solvable on my end. The graphics card is an Nvidia one, and the drivers have been regularly updated since the beginning while this issue has always been present, so I don't think the fault lies there. But I will triple check the whole thing, test each input ports with each input devices and various cables, to be sure. There is already an Integral 2 device between the AP25 output and the projector, to send a copy to the booth monitor, so I don't think the projector causes an issue either.

Thank you for the explaining the matrix decoding as well. Sounds like it might be more source of trouble with operators than anything else. I prefer having a stereo movie played in stereo instead of neo:6, rather than a surround movie played in stereo because someone forgot to change some settings at the source. However, I will definitely make sure the mic input is routed to the center speaker. This I know how to do .

I will do the software updates on the AP25 as well as do all the cable/input switching testing in the coming weeks and will report back

[Carsten Kurz]

Wondering wether you could have a second source connection from the PC (e.g. via S/P-DIF or TOSLINK) into one of the AP25 nonsync inputs. The apps playing content must then have a means to choose. You could have 5.1/7.1 LPCM from the HDMI, and stereo or AC-3/DTS over S/P-DIF or Toslink. We have a backup analog connection from the soundcard into our AP20. Teaching staff about such things is nearly impossible if they don't come with a natural interest in these technical aspects of presentation.

[Karim Benmachiche]

Teaching staff about such things is nearly impossible if they don't come with a natural interest in these technical aspects of presentation.

Hmm, we could output from spdif, but if you do that, don't you lose hdmi video pass-through in the AP25? We got sold on the AP25 because of hdmi switching and video/audio deembedding, so everything is hooked up with that in mind. Don't you have to output your video another way if audio is going out through spdif?

Anyway, if the AP25 simply ignores Neo:6 when receiving a 5.1 format, than it seems to me that the easiest would be to switch between stereo/Neo:6 and surround at the pc side. Of course if the AP25 doesn't do anything when it receives a surround format because Neo:6 is enabled, that's a problem.

About the other issue: I am more and more prone to think the problem lies somewhere within Windows or the card, rather than the AP25. The only reason I originally suspected the AP25 could be at fault was the release notes for the 1.06.09 upgrade... but it definitely does not concern our hdmi board. I checked and the hdmi software is already up to date. I am fairly hopeful some kind of EDID device will solve this problem. I will test with the Integral 2 device we already have.

[Carsten Kurz]

There is another 'plain' matrix decoder option in the AP20/25 - but I think it only works on the AES/EBU, or, DCP, inputs, not HDMI. I have to check, though.

[Paul Finn]

Whenever there is a HDMI connection problem, I've found the first thing to do is change the output resolution from the video source device (especially computers), which is probably 1920x1080P with HDCP protection(s), to 1280x720P and see if the problem is resolved. The OP did not say what the projector is, but most DCI projectors will upscale the HDMI input resolution to 2K for the screen. It is also not clear to me herein if the problem is new with the present setup. In almost all situations 1280x720P source video will provide a satisfactory picture, if necessary, even on a temporary basis.

Paul Finn

[Marco Giustini]

Paul - reducing resolution will reduce the bandwidth of the signal being used.
If a lower resolution fixes the problem, I would try a different HDMI cable. They can indeed be sensitive and sometimes an expensive cable is not necessarily a good cable unfortunately.
Longer cables - > 5m - can be problematic for sure.

[Karim Benmachiche]

The projector is not a DCI projector, it's a 3LCD laser panasonic projector, we screen in 1920x1080.

We only use certified hdmi cables. Only the cable going to the projector is 7.5m, others are 0.5 / 1m. The issue is present since the beginning. Hot plug events work, the problem is only with the hdmi input switching. But I am fairly sure it's an nvidia issue, I have found some similar problems reported. I just haven't had enough time ahead of me to plan to test everything thoroughly, the setup is getting too much use with public at the moment and I don't want to risk breaking something people operating it know how to get around of.

[Marco Giustini]

Last time I checked - fair enough, it was a few years ago - HDMI cables were a very much hit and miss. Even good brands could end up making poor cables as the testing facilities for those cables were quite expensive. 7.5 metres is still quite a long cables, the standard was never created with such length in mind - but again, the standard has evolved and I am not 100% familiar with it.

I would definitely try a shorter cable - if you can run a temp one - to see if the issue stays.

[Paul Finn]

My intention in recommending trying a lower resolution FIRST was to eliminate all of the HDCP image transfer issues/complications enforced with1920 x1080P video. HDCP requirements on the HDMI output of most computers are only present with 1920x1080P FULL HD video. Even 1920x1080i HD video does not have the HDCP requirement. Knowing if HDCP is causing the problem, or not, can go a long way in troubleshooting the problem.

Paul Finn

[Marco Giustini]

HDCP is only enforced on Full-HD resolutions?

[Marcel Birgelen]

The default behavior of a HDMI source whenever the sink does not support HDCP is to switch to an "SD" resolution. This is what your average BluRay player would be doing in such an event. For graphics cards, the problem is more complicated and as such, they usually don't start to switch resolution, they simply refuse to output a signal, if HDCP is required and the sink doesn't acknowledge.

Your HDMI signal is essentially divided into two channels, running over physically separated wire bundles. There is a "low bandwidth" channel, used primarily for signalling events. The EDID handshake is also performed over this channel and then there is the "unreliable channel" used for the payload data, usually the image data. If your image data isn't corrupted, then your cable length is fine. Your image data will start to see issues way before handshakes will get lost and broken due to excessive cable lengths.

HDMI is a complicated stack of protocols and the whole EDID thing is part of the problem. It was designed with "zero-end-user-configuration" in mind, but it's purpose got lost in half-assed specifications and vendor implementations.

In your case, you can spend hours and hours on installing software updates and trying to debug this, but your best bet is the HD Fury DR HDMI device, which costs somewhere around $100 including shipping and will keep your EDID stable, no matter what happens with the signal behind it.

[Marco Giustini]

well... my home theatre AVR was going to the projector via a wall HDMI sockets. Every now and then - not every time - the projector would lose signal, picture would flash a few times and then it would stabilise. It would happen only once or more or it would start and never stop.

I changed all cables a few times for then realising it was one of the HDMI Female-Female couplers on the wall. I removed it (routing the cable out of the wall directly into the projector) and never had an issue since.

The picture would be perfect in between those events.

I have tons of examples similar to that!

an HD Fury is probably a good idea though.