MacBook Air won't display properly when connected to projector via HDMI

usagora · Jun 21, 2020

For years, the only connection I've used to connect my MacBook Air to my Epson projector has been a VGA cable with a VGA-to-Thunderbolt adapter. The projector has a native resolution of 1280x800 (16:10) and my MacBook Air has a native resolution of 1440x900 (16:10). Using the VGA connection, the image fills the screen perfectly, which of course makes sense since both the computer and projector have the same aspect ratio.

So here's my problem. I've recently added an HDMI cable to the setup to be able to use an Apple TV with the projector as well. I've routed this cable to a much more convenient access point than the wall-mounted VGA port, so I'd prefer to simply use it as my primary connection to connect the projector to either the Apple TV or the MacBook Air using an HDMI switch. However, when I connect the MacBook Air to the HDMI cable with a HDMI-to-Thunderbolt adapter, the projected image is 16:9, and thus is stretched and letterboxed at the top and bottom. No matter what options I select on either the projector or the MacBook Air, I can't seem to make the darn image display at a full-screen 16:10 aspect ratio. If I go to System Preferences > Displays and select to optimize the settings for the Built-in Display (vs. the default setting of optimized for the Epson PJ), the projected image becomes 16:10 but is letterboxed now on all 4 sides.

So what gives? Is it not possible to fill a 16:10 projected image of a 16:10 MacBook Air using HDMI? See pictures below I took using a projector at home that is also 1280x800. I marked the corners of the "screen" in red so you can more easily see the letterboxing. I'm also having similar issues mirroring the screen using the Apple TV, but I'll leave those details out for now to avoid information overload.

USING VGA - fits screen perfectly

USING HDMI ("optimized for projector") - letterboxed on top and bottom

USING HDMI ("optimized for built-in display") - letterboxed all around

usagora · Jun 23, 2020

Any thoughts on this? I've even posted on a dedicated AV forum with no replies. I figured this would be a "duh!"-level easy solution to someone else and I was just missing something obvious. I'm having the same problem mirroring through the Apple TV as well - best I can get is the 16:9 letterboxed output (or the 16:10 letterboxed all-around output if I select "optimize for buuilt-in display). Since the Apple TV was the only reason I ran the HDMI cable, I guess I can try connecting it via the VGA cable instead using an adapter and see if that solves the issue. I just wish I understood what the issue was.

usagora · Jun 24, 2020

PLEASE HELP!

So to recap, my issue is that I can't get my MacBook Air to display in 16:10 FULL SCREEN (NOT letterboxed) with my Epson projector either through HDMI or Apple TV Screen Mirroring. So I ordered an HDMI-to-VGA adapter (male HDMI to female VGA) to see if screen mirroring would work in 16:10 fullscreen if I used the VGA cable.

But to my surprise, the Apple TV will not output ANY video AT ALL with this setup. I checked the HDMI-to-VGA adapter by using it with the MacBook Air, and it works, so I know the adapter isn't bad.

Here are the signal chains I tested (results in red):

Apple TV > HDMI-VGA adapter > VGA cable > projector: no video signal detected

MacBook Air > Thunderbolt-HDMI adapter > HDMI-VGA adapter > VGA cable > projector: displays correctly as 16:10 full screen

Blu-ray player > HDMI-VGA adapter > VGA cable > projector: acts like it's trying to connect, but displays message: "Not supported H: 67.33 kHz V: 59.84 Hz"

I thought the Blu-ray player result indicated that maybe I just needed to change the output frequency of the Apple TV (though the projector never displayed this error message when connected to it), but even changing the resolution to 1080p 24Hz (vs. the default 60Hz) didn't change anything.

The only other thing I can think of trying is an HDMI-VGA cable. But does ANYONE (pretty please?) have any thoughts before I buy something else?

All I really want to do is screen mirror my MacBook Air with the Apple TV in full-screen 16:10, which is the native aspect ratio of the 13" MacBook Air. WHY IS THIS SO HARD?

ferrarr · Jun 24, 2020

Are you setting this up in, mirror mode, or extending the desktop?

usagora · Jun 24, 2020

ferrarr said:
Are you setting this up in, mirror mode, or extending the desktop?

As seen from the screenshots, mirror mode, but that shouldn't have anything to do with the aspect ratio issue.

Ok, I believe I've solved ONE of the TWO issues. One thing setting I hadn't touched when connecting the MacBook Air to the projector via HDMI was the Underscan setting in System Preferences > Display. It was set to Off, so I moved the slider back and forth to play with that and then turned it back to "off." The image was currently the stretched 16:9 with letterboxing at top and bottom. I then selected Optimize for: Built-in Display and went to scale the resolution to 1280x800 to match the projector, which before cropped everything off all the edges...I was going to then adjust the Underscan setting to hopefully bring the full image into view. Well, lo and behold, as soon as I selected 1280x800 scaled resolution, the image now appears correctly - fulls screen with no cropping or letterboxing! SO STRANGE. The only two things that have changed since I tried this the other day were upgrading to Catalina and moving the Underscan slider...but I had moved it back to "off," so it shouldn't have made a difference.

Unfortunately, I still cannot get the image to display correctly using screen mirroring with the Apple TV. Even if I turn the Underscan setting on Apple TV to On, I still get cropped off edges if I scale both the Apple TV and MacBook Air to 1280x800. There's no Underscan slider on the Apple TV that I can see.

krs · Jun 24, 2020

I don't have an obvious solution, but let me throw out a couple of things:

1. I have used Epson projectors connected to MacBook Pros, usually via a DislayPort to HDMI cable (or adapter with an HDMI-to-HDMI cable) and occasionally had the problem with no display.
What eventually worked was trying all combinations of plugging in the cable with the Mac and/or projector powered/non-powered.
I just tried all possible combinations - unfortunately I didn't keep a track of what actually worked in the end....but I vaguely remember the "proper way" of plugging in both ends of the cable and then powering up the projector and the Mac did not work for me.

2. On the Apple TV side (and I don't have the product) -are you sure Apple TV can actually output at a 16:10 aspect ratio?
From what I have read, it will only output at a 16:9 aspect ratio since that is the aspect rato of all modern flat screen TV sets (and even most monitors)

3. Which Epson projector model do you have? Using VGA connectivity is a step backwards if all your devices can handle digital video.

usagora · Jun 25, 2020

krs said:
I don't have an obvious solution, but let me throw out a couple of things:

1. I have used Epson projectors connected to MacBook Pros, usually via a DislayPort to HDMI cable (or adapter with an HDMI-to-HDMI cable) and occasionally had the problem with no display.
What eventually worked was trying all combinations of plugging in the cable with the Mac and/or projector powered/non-powered.
I just tried all possible combinations - unfortunately I didn't keep a track of what actually worked in the end....but I vaguely remember the "proper way" of plugging in both ends of the cable and then powering up the projector and the Mac did not work for me.

2. On the Apple TV side (and I don't have the product) -are you sure Apple TV can actually output at a 16:10 aspect ratio?
From what I have read, it will only output at a 16:9 aspect ratio since that is the aspect rato of all modern flat screen TV sets (and even most monitors)

3. Which Epson projector model do you have? Using VGA connectivity is a step backwards if all your devices can handle digital video.

Thanks, krs, for your input.

1. The "no display" issue was only when trying to connect the Apple TV to the projector via VGA using a VGA-to-HDMI adapter. I always hot-swap out cables with both the projector and the source device (Mac or Apple TV) running, but nothing worked. The only reason I was trying VGA was because I figured if I was having no issues using VGA with the MacBook, the maybe the Apple TV would mirror my MacBook as expected if I used VGA with it as well. But for some reason, it simply doesn't respond. I guess I can try again tonight. The good news, though, as mentioned in my previous post, was that I did manage to get the MacBook Air projecting correctly using the Thunderbolt-HDMI and HDMI cable by scaling the MBA to 1280x800, though I will test again tonight using my HDMI switch to be sure all is still well. So IF ONLY I could get the darn Apple TV to mirror my MBA in full-screen 16:10 (not letterboxed around all sides), I would be good to go :'(

2. Yes, there are a bunch of resolutions you can change the Apple TV to, including 1280x800 (16:10), which is the same resolution as the projector. You would think that would be the answer, since all three devices (MacBook Air, Apple TV, projector) are set to output 1280x800 (assuming you scale the MacBook down from 1440x900), yet the image is cut off on all sides (and again, turning the AirPlay Underscan setting to "on" on the Apple TV doesn't make a difference).

3. For my testing at home, I've been using an Epson EX7210, and the permanent setup (which is not at home) is an Epson PowerLite 485W, but they are both identical resolutions (1280x800). So obviously these are not full HD projectors, let alone 4k, so I'm well within the VGA capabilities. This is for presentations, not home theater.

iggibar · Jun 25, 2020

I have an HP DLP 1080p projector that runs native 1080p, and has DVI, VGA, and component inputs. I had to have a lengthy come to Jesus moment with my projector over some beer trying to figure out how to connect all my devices and have no compatibility issues.

Although I can output HD resolution through VGA, I always have issues with compatibility and adapters. If I mirror my desktop, the image is always cropped.
This is because the 'lit portion' portion of projectors screen that does not have an image processed through it is usually natively at the max aspect ratio.
The only way to push a video signal on the screen to its max resolution is to run through DVI or component while using the projector as a second display.
I believe VGA adapter cables have a problem with bandwidth from my experience. The image is fine, but disconnects as soon as media is played.
If I use the projector in mirroring mode, the projector will always use the native aspect ratio of the computer that it is currently connected to, which will in turn look cropped because those computers usually were the original 13" Macbook Pros. Running the projector as a second display is the only way I've been able to run the max resolution and screen width that is allowed. And for whatever reason, component is so much more reliable for me, and I can easily split the video from the audio so that I can use fiber optic audio through my sound system.

usagora · Jun 25, 2020

iggibar said:
I have an HP DLP 1080p projector that runs native 1080p, and has DVI, VGA, and component inputs. I had to have a lengthy come to Jesus moment with my projector over some beer trying to figure out how to connect all my devices and have no compatibility issues.

Although I can output HD resolution through VGA, I always have issues with compatibility and adapters. If I mirror my desktop, the image is always cropped.
This is because the 'lit portion' portion of projectors screen that does not have an image processed through it is usually natively at the max aspect ratio.
The only way to push a video signal on the screen to its max resolution is to run through DVI or component while using the projector as a second display.
I believe VGA adapter cables have a problem with bandwidth from my experience. The image is fine, but disconnects as soon as media is played.
If I use the projector in mirroring mode, the projector will always use the native aspect ratio of the computer that it is currently connected to, which will in turn look cropped because those computers usually were the original 13" Macbook Pros. Running the projector as a second display is the only way I've been able to run the max resolution and screen width that is allowed. And for whatever reason, component is so much more reliable for me, and I can easily split the video from the audio so that I can use fiber optic audio through my sound system.

I think we may be using the word "cropped" in two different ways. When I say cropped, I'm referring to literally the bottom half of the dock being cut off (for example). I think you're meaning letterboxed, where the full image of your desktop is projected, but just doesn't fill the entire "lit portion" of the projected image (there are "black bars" at the top/bottom or left/right), like in the 2nd and 3rd images in my OP.

My main issue now, again, is with this darn Apple TV not mirroring a 16:10 ration, even when the Apple TV, MacBook, and projector or all set at a 16:10 ratio resolution. That's a complete mystery to me, but I figure it must be something to do with the "Airplay" technology vs. a direct cable connection. The only 16:10 image I can get to display is letterboxed all around (as seen in my 3rd image in the OP). If I could just get the thing to "overscan" to enlarge that image, it could fill the entire lit portion of the screen. But I don't see any way to do that.

I'm happy I at least got the wired HDMI connection now working properly, but I'd really like to be able to go wireless too without wasting a perfectly usable portion of the screen with unnecessary letter-boxing. SO frustrating! I think I'll post on the Apple forums tonight and see if any Apple TV gurus might be able to solve this conundrum.

I edited one of the photos above to illustrate what I mean by cropped. Something similar to this happens when I try to change everything to 1280x800 when using AirPlay with the Apple TV. There is an "Underscan: on" setting on the Apple TV, but it has no effect on this, contrary to logic.