HDMI-SDI Micro converters - can I create a 4:3 output?

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Eric Kron

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HDMI-SDI Micro converters - can I create a 4:3 output?

PostMon Sep 04, 2017 11:04 pm

Hello all,

Question about using micro HDMI-SDI (and micro SDI-HDMI) converters to push signals to XGA (1024 x 768) projectors.

Background: installed new XGA projectors (2) in my church this morning. Connected our existing VGA cables, but also ran SDI and installed BMD micro converters.

It seems like these converters always want to push a widescreen image. When I play a widescreen video that's fine (I get the black bars on the top and bottom of the screen as expected). When I attempt to play something that's 4:3 (video, older PowerPoint slides) I get black bars on all 4 sides of my image, rather than having the image fill the screen. My projectors always report that they're receiving a 1080p signal, regardless of what I set my PC video card to output.

Given that our screens and our projectors have native 4:3 resolutions, is it possible to configure any of the BMD devices to always send 1024x768 resolution? Is there another piece of the puzzle that I'm missing?

Here's my basic signal route:

2 laptops, both connected by HDMI into a BMD micro HDMI-SDI converter.
SDI cable to a switch
SDI cable out to projector 1 (BMD micro SDI-HDMI converter)
SDI cable from projector 1 (BMD micro SDI-HDMI converter loop out) to projector 2 (BMD micro SDI-HMDI converter)

Thank you for any help you can give me.

Best regards,
Eric
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Xtreemtec

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Re: HDMI-SDI Micro converters - can I create a 4:3 output?

PostWed Sep 06, 2017 9:54 am

The micro converters don't do anything with the signal.. It outputs what comes in..

But what could be is that you put your beamer in 16:9 mode creating a black bar on the top and bottom. (Fairly common on projectors to crop this way..)
Then the moment you send a 4:3 slide to it.. The laptop will put black bars left and right to fill it out.. But on your projectors it looks like 4 black borders.

The green is your beamer image area.. YOur laptop and the BMD converters are 16:9 so the purple is your laptop video area.. So when you playback 4:3 slides on your 16:9 output of your laptop you will get black borders all arround..

And live switching between 16:9 and 4:3 mode in the beamer is not that nice.. So try to upgrade the 4:3 slides to 16:9 slides is your best solution. ;)
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Eric Kron

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Re: HDMI-SDI Micro converters - can I create a 4:3 output?

PostThu Sep 07, 2017 3:30 am

Thanks for the reply. It seems that no what resolution I attempt to output it ends up as a 16:9. Regardless, seems like you're right. Solution is to reformat stuff to 16:9 (not a huge deal). I still have VGA cables available if someone insists on a (bad) 4:3 screen.


Xtreemtec wrote:The micro converters don't do anything with the signal.. It outputs what comes in..

But what could be is that you put your beamer in 16:9 mode creating a black bar on the top and bottom. (Fairly common on projectors to crop this way..)
Then the moment you send a 4:3 slide to it.. The laptop will put black bars left and right to fill it out.. But on your projectors it looks like 4 black borders.

The green is your beamer image area.. YOur laptop and the BMD converters are 16:9 so the purple is your laptop video area.. So when you playback 4:3 slides on your 16:9 output of your laptop you will get black borders all arround..

And live switching between 16:9 and 4:3 mode in the beamer is not that nice.. So try to upgrade the 4:3 slides to 16:9 slides is your best solution. ;)

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