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Picture aspect problem with Foxsat to Panasonic plasma TV via HDMI-to-VGA converter

David230757

New Member
For a long time I’ve used a “Scart-to-VGA-converter” to link my Foxsat HDR (with CF) to a Panasonic TH-42PWD4 plasma TV and everything works fine. The TV is old but I really like the picture and don’t want to upgrade.

I’m now trying to link them up using an “HDMI-to-VGA-converter” that I can also use to play other HDMI devices on the TV. I tested it with an Android tablet and the picture’s good.

But when I hook up the Foxsat via HDMI the picture is approx 4:3 and positioned over on the left-hand side. Changing the TV aspect control (4:3/Zoom/16:9) doesn’t use any more of the screen. I can use the TV’s picture position & size settings to stretch the picture but the maximum width still isn’t wide enough so it's a poor workaround

I’ve tried every permutation of Humax setting I can think of: at 720P resolution (via the V-Format button) I set the screen ratio to 16:9 and tried all the available display formats. I then changed the screen ratio to 4:3 and tried all the available display formats. And I repeated all this with the other (“Original”) resolution

I've thought of sticking with my existing setup for the Foxsat and getting an "HDMI-to-Component-converter" for other devices. But I think I should be able to get this to work somehow. Any ideas?
 

MofTot

Member
Hi David

Are you watching SD or HD content on the Foxsat-HDR? I'm wondering whether there's something related to HDCP that isn't properly handled by the HDMI-to-VGA converter with HD.

What's the max. resolution you can get over this combination? 576p?
 
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David230757

New Member
It's SD. I don't understand much about resolution but the Foxsat manual says the resolution is 1080i 720p 576p 576i. There's a button on the remote to change resolution & which cycles between 720P and Original.
 

MofTot

Member
It's SD. I don't understand much about resolution but the Foxsat manual says the resolution is 1080i 720p 576p 576i. There's a button on the remote to change resolution & which cycles between 720P and Original.
Yes but the questions is whether the HDMI-to-VGA downscales the output to SD 576p anyway so it wouldn't make sense to watch an SD channel, ask the Foxsat to upscale from SD 576p to 720p or 1080i, the HDMI-to-VGA converter then potentially downscales to 576p and not sure what your TV does in the end.
 
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David230757

New Member
The info on the converter says it doesn't perform any video scaling, you select the resolution you want to run on the source. It supports up to 1080p Full HD
 

MofTot

Member
The info on the converter says it doesn't perform any video scaling, you select the resolution you want to run on the source. It supports up to 1080p Full HD
That's impressive over VGA, what resolutions does your TV support on the VGA input?
 
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David230757

New Member
I don't really know what I'm talking about but the TV manual says it has 2556x480 dots and the display resolution with VGA is max 640x480 at 4:3 and 852x480 at 16:9. Panasonic TH-42PWD4.
 

MofTot

Member
I don't really know what I'm talking about but the TV manual says it has 2556x480 dots and the display resolution with VGA is max 640x480 at 4:3 and 852x480 at 16:9. Panasonic TH-42PWD4.
There's your answer. You would have to be able to limit the VGA output from the converter to max. 852x480 to make this work.
 
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David230757

New Member
sorry if this is a dumb question but if that's the problem then why does it work OK with the Nexus 10 which has a 2560x1600 px resolution?
 

grahamlthompson

Well-Known Member
There are three parameters that determine the aspect ratio shown by a display. One is the Source Video Frame Resolution, Two is the display native resolution, Three is the Pixel Aspect Ratio (PAR) which the video stream should have embedded required to produce the correct frame aspect ratio.

Simple example a UK DVD in 4:3 and one in 16:9 both have 720 x 576 pixels but have a different PAR. A 1440 x 1080 video source will show correctly on a 1920 x 1080 display because the display correctly knows the embedded pixels are to be displayed wider than tall (rectangular) compared to a 1920 x 1080 PAR of 1:1 (Square)

Seems likely the display that distorts the picture is ignoring the Pixel Aspect Ratio data. The Nexus 10 is correctly scaling the source to fit the screen and maintaining the correct frame aspect ratio.

https://wolfcrow.com/blog/understanding-terminology-aspect-ratio-and-pixel-aspect-ratio/

https://helpx.adobe.com/premiere-pro/using/aspect-ratios.html

https://en.wikipedia.org/wiki/Pixel_aspect_ratio#Pixel_aspect_ratios_of_common_video_formats
 
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