MacBook Air M2

[Upstage46]

HI 

Anyone had a problem with the display output on theMacbook air M1 mine just switches on and off when I try to connect it any peripheral device ie Decimators Switchers etc 

Any ideas ?

[Stuart91]

Possibly related to the HDCP copy protection?

[Upstage46]

HDCP switched off on switchers so no joy there.

Bizarrely when plugged into a monitor it works fine  

[alistermorton]

Isn't that the point of HDCP - it works when it is connected to a single display device, such as a monitor, but doesn't allow distribution? So the decimators need to send the right HDCP handshake so the MacBook doesn't think you're pirating. 

 

Or have I missed something?

[Stuart91]

36 minutes ago, alistermorton said:

Isn't that the point of HDCP - it works when it is connected to a single display device, such as a monitor, but doesn't allow distribution?

Yep - and unfortunately there seems to be no way of turning HDCP off on the Mac, even if you are showing non-protected content. 

Some cheap HDMI splitters will strip the HDCP from the signal, which is technically illegal but a very common workaround. 

[J Pearce]

The macbook air has no native HDMI, so you'll be using some form of adapter? I'd suggest swapping this out, I've had issues with cheaper USB-C adapters - notably some don't support 1080p60, and some seem really keen on outputting 4K30 despite what the settings might suggest it should output - so it may be that the decimator is not getting a video format that it can handle properly.

[adamburgess]

Had an issue with more than one AV adapter not being able to cope with 1920x1080 going in to an LED wall server.

One was a no-name Apple AV copy, one was a U-Green dual USB-C adapter. These worked fine into the venues 800x600 projector, and a Samsung TV or two, but no dice with the LED wall. Caused a load of problems with the Mac just going blank; but, sometimes it would work and the list of resolutions was very weird.

Proper Apple one fixed it right away.

[dosxuk]

I'd be surprised if it isn't HDCP related. The big clue is a picture being visible for a few frames and then going black.

Converters like the Decimators / Blackmagic don't support HDCP - it's not supposed to be available on anything that will give you a decrypted version of the source signal otherwise it would just give people a cheap and easy option to remove the copyright protection. Mac's are notorious for turning on HDCP for no reason, even when just displaying their desktop.

[Stuart91]

58 minutes ago, dosxuk said:

Converters like the Decimators / Blackmagic don't support HDCP

Also worth mentioning that SDI doesn't support HDCP either, which can catch people out. 

[alistermorton]

ISTR HDFury devices being recommended to work around HDCP - worth looking into?

[J Pearce]

I'd be checking a different USB-C/Thunderbolt to HDMI adapter before investing in anything further.

[Upstage46]

Thanks everybody for your replies I will try a genuine Apple dongle and see if that cures the problem.