Audio Device Issues/confusion with multiple active TB to HDMI adaptors

[Freddy Komp]

Hi there,

I wondered if there is a better way to reliably manage recognition of HDMI audio devices; While i.e. their video source can be reliably identified if they have different EDIDs, it does not seem to be the case with their attached audio devices - case in point, it often seem to generate either audio devices called "Display Port" or "HDMI", and if there are several ones, it seems to enumerate them ("Display Port 2", "HMDI 3").

Is there any way to use i.e. the name provided by the EDID? I am working on a project that uses multiple outputs where both the audio and video routing (and their togetherness) are crucial, and find inconsistent results (although I boot with a strict order of events, i.e. only have the control monitor attached, and then attach each QLab HDMI AV output one by one, let it be recognised, and only then open QLab. Display wise, this now seems to work fairly well, but the audio seems to change each time I do it.

This is on a Trash Can (late 2013) on Mojave 10.14.6, and was on QLab 4.6.10 (just updated to 4.6.12).

Any hints or thoughts would be appreciated.

Cheers,

Freddy

[Sam Kusnetz]

Hi Freddy

I am not aware of any solution to this, unfortunately. Things like this remind me of the fact that HDMI was designed as a consumer connector for AV equipment, not originally intended to be used with computers or pro level video equipment, and so situations like the one you describe were not planned for because they were not imagined.

It could be possible to get around this if you use an EDID manager that lets you manually configure the EDID itself, like a DVI Parrot. I’m not sure about that, but it’s possible.

Best

Sam

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Sam Kusnetz (he/him) | Figure 53

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[Freddy Komp]

Hi Sam,

Thanks for your answer! Sorry, I might not have been clear with what I meant to say; It seems that on a MacOS level, there is a tie from the Audio Device to the HDMI source, see the attached screen grabs from the Terminal App system_profiler and the Audio Midi Setup App; The same audio device names are used (i.e. DisplayPort 1,2,n), but there is a "Source" name that seems to be related to the reported EDID name. Would it not be possible to rename the devices in QLab to be either

- a combo of both, i.e. "DisplayPort 1 - HDMI to USB", or probably even more useful, source first "MACROSILICON (DisplayPort 1)", or

- if it can or from a usability perspective only be one, then just the source name, i.e. "HDMI to USB"?

That way, there would be much less guess work and an easier, more consistent way of keeping tabs, no?

Thanks for considering!

Cheers,

Freddy

[Sam Kusnetz]

Hi Freddy

Aha, yes, I did not understand what you were saying at first. Thanks for the screen shots… that’s pretty interesting, I never knew this!

I don’t know for sure if we can do something like this, but we’ll take it under consideration. I definitely see how it could help.

-sk

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[Freddy Komp]

Hi Sam,

Thank you for looking into the feasibility of this - and on second thoughts, the Source name alone as identifier is probably a bit "sturdier", as that could survive plugging the same device into a different port... The remaining issue will always be with multiple identical EDIDs (i.e., if you used 2 HDMI destination that use the very same EDID) - unless it was reliable Connection numbering, be it per port, or per order of being connected... if that was reliable, then the combination of source AND connection would allow uniquely identifying/telling apart when more than one device with the same EDID would be connected. I wonder if the combination might even be helpful to keep Video Outputs apart, too (as there, it does not look like the Connection is used as part of the identifier, but maybe EDID plus Resolution?)

Cheers,

Freddy

[Sam Kusnetz]

I’m sorry, Freddy, but I’m having a very hard time parsing what you’re saying here.

EDID uniqueness cannot be relied upon because many manufacturers, ViewSonic I’m looking at you, do not properly include the unique serial number of their device in the EDID as they are supposed to.

Order of connection cannot be relied upon because QLab cannot reliably know what happened before it launched. Furthermore, if two displays are connected at boot time, which one comes “first” is almost a matter of random chance.

What we can (possibly) do is display the bit of information that you pointed out in the EDID payload. I’m not sure we can, but we maybe can and I definitely see how that could help.

Best
Sam

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[Freddy Komp]

Hi Sam,

Sorry if I was less than clear, and/or have misunderstood the way audio devices and/or video devices are enumerated/counted in MacOS and QLab respectively;

I guess the overall goal would be to have a system in QLab that uniquely identifies devices, remembers them, and recognises them, ideally even if they have been plugged into a different port, although I would argue this last goal could be sacrificed on the altar of unique identification for those pesky identical-EDID-identical-SN cases - i.e. you have two indistinguishable EDID-SN combination, but through ALSO tracking the connection if uniquely identifiable (see two paragraphs down), being able to uniquely identify them (better than at the moment)?

Since I have often encountered in the past that I would not boot a Mac with projectors attached (as this has otherwise sometimes selected one of these projectors as the primary display), I don't mind this as a pre-requisite, i.e. - boot with only your internal display (MacBooks) or primary control display (Macs) attached, then, one by one, plug in the projectors - while this has not been 100 percent reliable in all cases, in most cases it meant it restored the last configuration (including the set resolutions per individual display) correctly. Only then open QLab.

Now, the question is - when you see i.e. in the Audio Midi Setup things like "DisplayPort 1" and "HDMI 3" - is this numbering reliably tied to the order of things plugged in, and thus usable if the plugging it in is done in a consistent order?

And, would QLab be able to access this ordered numbering, or does it make its own numbering up (as I noticed Audio MIDI Setup "DisplayPort 1" and "HDMI 1" versus QLab "DisplayPort" and "HDMI" ), as well as the Source Information to tie AudioDevices to EDID's, in the sense of giving the audio devices more of a unique identifier other than noting its connection as being i.e. one of the potentially many DisplayPorts?

I hope I was able to explain it better - it just is a bit of a complex issue to break down clearly :).

Cheers,

Freddy

[Sam Kusnetz]

It is a very confusing topic! Thanks for clarifying your thoughts.

Some specific answers:

I guess the overall goal would be to have a system in QLab that uniquely identifies devices, remembers them, and recognises them,

If two devices do not have unique EDIDs, then there is quite literally nothing QLab can do to tell them apart. Let’s pretend that EDID is just a single digit number, and let’s say you have two projectors that have an EDID of “6.” When they’re both plugged in, QLab can easily say “ok well there are two ‘6’ projectors here, so I’ll call them 6A and 6B” and everything is OK. But after a reboot, or if only one is plugged in, QLab has to decide “now, which one of these was 6A?” and the device has no uniquely identifying information so QLab simply cannot know.

Now, the question is - when you see i.e. in the Audio Midi Setup things like "DisplayPort 1" and "HDMI 3" - is this numbering reliably tied to the order of things plugged in, and thus usable if the plugging it in is done in a consistent order?

I don’t know the answer for sure. I do know it’s not a simple as it seems like it should be.

as well as the Source Information to tie AudioDevices to EDID's, in the sense of giving the audio devices more of a unique identifier other than noting its connection as being i.e. one of the potentially many DisplayPorts?

Again, without unique EDIDs, the answer is sadly no.

The only true solutions to problems of this nature are to either use video devices with proper EDID, or hardware EDID emulators which can be configured to provide a unique ID.

Beyond that, all we can really do is make it easier for you to quickly say “THIS one goes here, THAT one goes there,” which we are taking another swing at in QLab 5. The new system is, in my opinion, a noticeable improvement.

Best
Sam