Could HDMI-DVI conversion be causing this?? - AVS Forum
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post #1 of 3 Old 02-10-2007, 10:10 AM - Thread Starter
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Hello, I've posted this in the HDTV recorders forum but thought I might get some feedback from here.

I've been using my LG 3410A STB for awhile now but have recently encountered a strange problem and hope someone may have a solution or advice.

I previously used the LG with my 720p PJ without issue. I now have it connected to a Sharp 1080p tv and am having issues. I can't get a 1080i signal from the LG to display properly on the sharp via HDMI. The Sharp is showing the 1080i signal from the LG with horizontal aliasing. It's like the full horizontal resolution is not being displayed. For example, overlays of sports scores or ticker tape scrolling along the bottom is somewhat blocky and looks low rez. The onscreen GUI of the LG is blocky also when it's set to display 1080i. 720p looks like it is supposed to.

Now, if I'm watching a 1080i program coming from the LG and suddenly switch to the same program via the tuner inside the Sharp, the 1080i signal is shown like it should be. I don't have any problem with the TV displaying 1080i from component either, only from the LG via hdmi-dvi. I have a pc connected via hdmi at 1080p and don't have any problem with that connection (but 1080i doesn't look right from pc via hdmi-dvi either).

At this point I'm trying to figure out if the problem is in the HDMI-DVI cable (should it be HDMI-HDMI connection only), or maybe the HDMI ports on the TV, or maybe something is wrong with the LG at 1080i and I didn't notice it before since I had it hooked to a 720p device.

Any input is appreciated.


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post #2 of 3 Old 02-11-2007, 07:18 PM
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Even though the video from DVI to HDMI should be straight forward, some differences do exist. I know that the video levels are different for each standard, so that black/white levels will not be the same between the two formats.

Check your menu settings to see if the monitor has the capability to change from HDMI video levels etc to DVI levels. You may see a capability in the menu you were not aware of.

The only other situation I can think of is the HDCP capability of the the tv downrezzing the video due to improper HDCP?

Hope this helps.

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post #3 of 3 Old 02-27-2007, 09:50 AM
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It sounds like there is compatibility problem with 1080i between the STB and TV. Your description makes it sound like the STB is going to 640x480 mode (blockly letters, 4:3 image) which is what a source does when it detects an incompatible video mode. If you're using the TV's tuner, then the TV's internal video processor takes over and can ensure the source video gets upscaled to the TV's native 1080p resolution properly, so it's no surprise that works fine.

I would offer that the problem is that either the TV does not support 1080i on HDMI (try checking specs from the manual or the STB has a firmware issue with sending 1080i out. If you hook up another 1080i source (such as an upscaling DVD player set to 1080i output mode), that will help you narrow it down.
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