Some Laptop / Intel IGP users report sync does not work

[BradyBrenot]

Some laptop/convertible users are reporting issues. Syncing does not work at all, and shows a black screen.

Trying to gather info. I cannot reproduce this at the moment with the hardware I have available.

Reported bad:

• Intel HD Graphics 520 (Surface Pro 4, Windows 10)
• Intel HD 4000 (? laptop, i5-3230M, Windows 7)

Reported good:

• Intel Graphics HD 530 (my desktop computer)
  • Either in multi-GPU mode (enabled alongside my dedicated video card), or on its own.
  • Which makes me think this might somehow be a laptop thing, not an Intel IGP thing, but I don't yet know how. There's a hint in the comments that some laptops do a thing with the external display, but I don't know if that's the case for recent ones like the Surface Pro 4.

Reports: https://www.reddit.com/r/Hue/comments/7yn2ei/huestacean_lowlatency_screen_sync_using_the/duik4mn/ https://www.reddit.com/r/Hue/comments/7yn2ei/huestacean_lowlatency_screen_sync_using_the/duszr0v/ https://www.reddit.com/r/Hue/comments/7yn2ei/huestacean_lowlatency_screen_sync_using_the/dvbpybw/

[BradyBrenot]

I've attempted to reproduce but I'm not getting anywhere. I have tried:

• Remove Nvidia video card from computer entirely, enable integrated Intel Graphics HD 530
• Change resolution to 1366x768 as reported by user

No reproduction. I'm not having any issues at all.

I might have a motherboard with an older Intel IGP sitting around.

[AbraKabastard]

Is this when actually running the process of Syncing? Before I sync the "display" is just a solid shade of Blue and he actually might not be syncing.

[Collisionc]

I've seen some older laptops have a 2nd monitor that shows up as a "display". I'm not sure what it's used for, possibly the hdmi output screen, but it could explain this, as that display would be completely black at all times.

[BradyBrenot]

Eh good point @AbraKabastard. The mbedtls code doesn't really gracefully recover from a fail but just sort of silently kills the whole thing. He should notice the button switch from (or stay at) "Start Sync", assuming that much is even working. I asked.

And @Collisionc I had no idea about that either. Blah, computers.

[BradyBrenot]

There's another report on the Reddit thread, from an HD 4000. I don't have one of those to test with but I know from Chivalry that they can have... issues...

[BradyBrenot]

Based on DXGI docs, forum threads, blah blah blah, it seems likely that this is something to do with portable devices with "hybrid" GPUs. The fix in bd585e5 might resolve it by letting users pick which adapter is used but, again, haven't got the hardware to test with.

bd585e5 also doesn't display on the GUI which output is for which adapter. Need to add still.

[BradyBrenot]

https://www.reddit.com/r/Hue/comments/7yn2ei/huestacean_lowlatency_screen_sync_using_the/dvq9qdw/?context=3

It looks like it does help in some circumstances. Still getting reports of HD 3000 / HD 4000 users with problems though.