Overscan / Crop settings

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Cadriel

134 posts

Master Geek

#26057 10-Sep-2008 20:07

Hi All,

Anyone else notice a small white dot on the top left of the TV2 Freeview|HD feed? I have, and since looking into it further - it appears as if all of my feeds display in a slightly different aspect to what I'm used to via a normal set top box.

Is there a specific overscan or crop setting I need to adjust for this? Also - is this going to break the 1 to 1 pixel mapping?

Sorry for all the posts too - so many questions are arising! :)

--
Craig.

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722 posts

Ultimate Geek

#163821 11-Sep-2008 17:56

Hi All,

Anyone else notice a small white dot on the top left of the TV2 Freeview|HD feed? I have, and since looking into it further - it appears as if all of my feeds display in a slightly different aspect to what I'm used to via a normal set top box.

Welcome to the weird world of HTPC. No to your first query. I haven't. The TV programmes will differ depending on their original aspect ratio mastering. You can adjust it by right-clicking on the screen whilst playing-back a TV programme, or pressing 'more' twice on the MCE remote. Click on change aspect ratio & select the preferred one. For Prime I often use zoom 14:9 & normal for most other TV stations.

Sorry for all the posts too - so many questions are arising! :)

The only stupid post is the one that is not posted.

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sbiddle

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#163824 11-Sep-2008 18:14

The white isn't a figment of your imagation - it does exist!

It's not something that really bothers me but isn't visible on a normal STB or TV since they are overscanned slightly.

Cadriel

134 posts

Master Geek

#163828 11-Sep-2008 18:28

Alrighty - if they're overscanned slighty, does anyone know by how much? And also - How do I achieve the same result in MediaPortal?

:)

--
Craig

1gkar

722 posts

Ultimate Geek

#163856 11-Sep-2008 20:47

Unless you are using your HTPC for 100% Mediaportal, I would not recommend attempting to rescale or resize your desktop resolution. Any attempt will result in losing your 1:1 pixel map. The simplest method is as I've described above. I would start with zoom mode as that seems to apply the least amount of overscan.

Afraid it is one of the limitations of HTPC. But I have also read threads where people using STBs are at the sufferance of varying aspect ratios since the advent of digital TV.

Cadriel

134 posts

Master Geek

#163944 12-Sep-2008 08:56

Hrmf.

My PC *is* 100% only used as an HTPC. However, I don't like the idea of losing the 1 x 1 pixel mapping - especially on the HD broadcasts.

What i've done currently is dropped 6 pixels from each side using the crop setting. This seems to have removed the fuzzy edges off most broadcasts.

However, the best scenario for me would be having a custom zoom mode per channel. At the moment, it seems to remember this setting across the entire range of channels, and obviously zoom mode is *not* suitable in all situations.

I notice the ability to set overscan / size within the mediaportal app itself (i.e., not the config tool). Is this suitable? Whereby it doesn't affect your desktop - only mediaportal itself. Also - how is this different to crop settings?

--
Craig.

Cadriel

134 posts

Master Geek

#163947 12-Sep-2008 09:10

Thinking about this some more..

wouldn't the most perfect solution be having the ability to set custom crop settings based on the type of broadcast coming through? Is that even possible?

E.g., widescreen sd broadcast - crop 20 on the left and right and 6 on the top and bottom.
widescreen hd broadcast - no crop
etc.

Can post processing handle that? Or at the codec level or something?

--
Craig.

Little

82 posts

Master Geek

#163948 12-Sep-2008 09:11

I use MediaPortals built in crop to remove 2px from the top and bottom. There are also some strange colours on the TVNZ6/7 channels that I crop out.

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Cadriel

134 posts

Master Geek

#163995 12-Sep-2008 14:16

Yep - that's essentially what I'm doing.

I think what's happening is we're seeing the full broadcast picture, but most set-top boxes and tv's overscan these pictures to remove the soft edges and artifacts at the edges of the broadcast.

This is especially apparent on sd 4x3 broadcasts on a 16x9 television.

--
Craig.

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#164040 12-Sep-2008 17:07

i was also cropping a few pixels from the top and bottom. i used to get a thin green line at the top of the screen on c4

HTPC / Home automation (home assistant) enthusiast.

1gkar

722 posts

Ultimate Geek

#164045 12-Sep-2008 17:28

Cadriel: Hrmf.

My PC *is* 100% only used as an HTPC. However, I don't like the idea of losing the 1 x 1 pixel mapping - especially on the HD broadcasts.

What i've done currently is dropped 6 pixels from each side using the crop setting. This seems to have removed the fuzzy edges off most broadcasts.

However, the best scenario for me would be having a custom zoom mode per channel. At the moment, it seems to remember this setting across the entire range of channels, and obviously zoom mode is *not* suitable in all situations.

I notice the ability to set overscan / size within the mediaportal app itself (i.e., not the config tool). Is this suitable? Whereby it doesn't affect your desktop - only mediaportal itself. Also - how is this different to crop settings?

--
Craig.

1:1 pixel mapping really is only relevant for text-type operations, such as browsing. It won't affect playback of media files.

Your suggestion of setting custom crop settings is a good one. Wish you could also set audio type for specific programmes ie. TV3 news AC3 audio is crap when using SPDif.

Not sure about the rest as I've never had reason to investigate. My LCDTV has a native resolution of 1360x768 so I'm automatically losing that screen area where, it seems the issue lies.

bazzer

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#164131 13-Sep-2008 02:30

1gkar: 1:1 pixel mapping really is only relevant for text-type operations, such as browsing. It won't affect playback of media files.

I'm interested in why you would say that?

1gkar

722 posts

Ultimate Geek

#164155 13-Sep-2008 09:01

bazzer:
1gkar: 1:1 pixel mapping really is only relevant for text-type operations, such as browsing. It won't affect playback of media files.

I'm interested in why you would say that?

http://pixelmapping.wikispaces.com/Pixel+mapping+explained

Take specific note of the second paragraph just below the bridge pictures.

But I probably could have been a little more accurate. I should have said, "Media files' playback quality will be minimaly compromised when using non 1:1 pixel map scaling."

aucklander

477 posts

Ultimate Geek

#164215 13-Sep-2008 14:06

Finally other people see the WHITE DOT !!! I always wondered what's the story with that dot, ONLY on tv2 !

I did not used to have it on the screen. But (I believe) it appeared after replacing the tv tuner (with an identical one, part of troubleshooting other issues at that time). I also get other strange dotted lines on TVNZ6/7 (on top).

So... just cropped the image using MP settings. But not too much, the dot is still there but much smaller, line on top of screen on TVNZ7 is still there (but not so thick).

Screen is 1366x768, nVidia card is set to 1360x768, TV set to "normal", which I assume is the 1:1 mapping. Text on desktop is crisp enough, easy to read.

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bazzer

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#164250 13-Sep-2008 17:29

1gkar:
bazzer:
1gkar: 1:1 pixel mapping really is only relevant for text-type operations, such as browsing. It won't affect playback of media files.

I'm interested in why you would say that?
http://pixelmapping.wikispaces.com/Pixel+mapping+explained

Take specific note of the second paragraph just below the bridge pictures.

But I probably could have been a little more accurate. I should have said, "Media files' playback quality will be minimaly compromised when using non 1:1 pixel map scaling."

Then I guess it depends how fussy you are. Just because it's easier to notice 1:1 mapping with text doesn't mean its any different with media playback, in my view. If the source is 1920x1080 and my screen res is 1920x1080 shouldn I expect 1:1 mapping? Why would I want unnecesary scaling steps to be introduced? Isn't the point of HD, high quality video? Why compromise?

1gkar

722 posts

Ultimate Geek

#164264 13-Sep-2008 18:52

bazzer:
1gkar:
bazzer:
1gkar: 1:1 pixel mapping really is only relevant for text-type operations, such as browsing. It won't affect playback of media files.

I'm interested in why you would say that?
http://pixelmapping.wikispaces.com/Pixel+mapping+explained

Take specific note of the second paragraph just below the bridge pictures.

But I probably could have been a little more accurate. I should have said, "Media files' playback quality will be minimaly compromised when using non 1:1 pixel map scaling."

Then I guess it depends how fussy you are. Just because it's easier to notice 1:1 mapping with text doesn't mean its any different with media playback, in my view. If the source is 1920x1080 and my screen res is 1920x1080 shouldn I expect 1:1 mapping? Why would I want unnecesary scaling steps to be introduced? Isn't the point of HD, high quality video? Why compromise?

Whilst that is probably true for all 1080p LCDTVs, there are a number of lesser specced LCDTVs that don't pass 1:1 via all their connectors. A number of threads regarding certain brand TVs not having 1:1 on HDMI exist. I agree, it is definitely preferable to have 1:1 working, even on a 100% dedicated HTPC, as I stated in an earlier post. If you have top of the range gear, the image artifacts will be more noticeable than with average equipment.

But we seem to have digressed from this thread's topic somewhat.

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