Hello all,
I am posting here because I am looking for a local (KC area) X resource. I am currently in the final stages of building a MythTV HDTV PVR. This is the first Linux box that I have built that is not headless. (read: usually I do not work with X.) Long story short, I can get the system to output to a standard monitor without issue (X does a fine job of determining the proper resolution) However, when I attach the system to my Toshiba HDTV (via DVI) I can only get it to output 800x600 (Image falls off the screen) or 640x480 (image does not fill the screen). At this point it is my understanding that I need to build a custom modeline but for the life of me with all the reading that I have done I cannot grasp the concept.
If you think that you are up the the task and interested, please let me know.
On another note, I would be interested in attending a meeting, but chances are I will be out of town mid week as I travel for a living. But if I happen to be in town I look forward to attending.
Thanks.
-Leland
On Thu, 2006-03-23 at 09:39 -0600, leland sindt wrote:
Almost every HDTV that I have seen and both of my HDTV's do NOT accept input from a computer even though they accept DVI connections. Does your Toshiba explicitly state that it will pull-down, transcode a computer signal?
I can't say that it does, but I have noticed that it returns EDID information. (tho it appears that X ignores/rules out the EDID returned resolutions.) I have (in the past) used the DVI connection to use a TimeWarner cable box... but I guess that does not mean that it will transcode the computer signal as you say. I will have to do some research, I purchased the TV w/o a manual so I will have to do some digging.
As a side note, I have one of these http://www.audioauthority.com/9a60.php on order. I read that alot of people have had luck with them over a DVI interface.
Jason D. Clinton wrote:
Right, So now I feel like a complete idiot... I should have RTFM sooner...
"The DVI/HDCP input is designed for best performance with 1080i high-definition video signals. The DVI/HDCP input also will accept and display 480p and 480i picture signals. Note: This TV is not intended for connection to and should not be used with a PC (personal computer)."
Thats what I get for making assumptions.
Lets just hope that the signal converter that I have on order helps.
Jason D. Clinton wrote:
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Luke-Jr wrote:
480p is approximately (but not quite) standard VGA. 480P video would be 720x480 progressive, vs. 640x480 for VGA.
I wouldn't give up quite yet on getting the monitor to work with your GPU, but you'll probably have to craft a custom modeline for X.
DISCLAIMER: I don't do much X stuff either, but I know HD pretty much inside and out (I design video hardware for a living, and am currently working on a baseband HD card for PCI Express).
Your monitor will likely be happiest with a 1080i HD signal (details to follow). In addition to the basic scanning parameters, you may have to worry about colorspace. DVI is typically RGB, but the newer DVI derived specs like HDMI allow YUV in 4:4:4 or 4:2:2 modes. Since you indicated some VGA resolutions worked (but didn't quite 'fit') with the monitor, and you didn't mention the colors being all wacked, I'll assume your toshiba supports RGB.
There are a variety of 1080i HD signal specs, based mainly on framerate (24 Hz for film, 25 Hz for PAL countries, 59.95 and 60 Hz for NTSC countries). Good ol' American 59.95 Hz 1080i would have the following specs per SMPTE S292M:
Pixel rate: 74.25/1.001 MHz (apx. 74.176 MHz) Active H pixels: 1920 Total H pixels: 2200 Active lines: 1080 Total lines: 1125
A quick google search turns up the MythTV modeline database, which has the following entry that looks like it might work for you:
#ModeLine "ATSC-1080-59.94i" 74.176 1920 1960 2016 2200 1080 1082 1088 1125 Interlace
You might also want to try the other ATSC-1080-*i and ATSC-480-* modes listed on that page, since that's what your monitor claims it supports well.
- -- Charles Steinkuehler charles@steinkuehler.net
On Friday 24 March 2006 23:38, Charles Steinkuehler wrote:
#ModeLine "ATSC-1080-59.94i" 74.176 1920 1960 2016 2200 1080 1082 1088 1125 Interlace
Wow, nice info here. I had no idea video cards could be made to output interlaced video! Think it is possible to get interlacing with a regular monitor (VGA cable?) and switch to it for watching interlaced video?
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Luke-Jr wrote:
Yes, the video cards will output analog interlace video on the VGA connectors...it will be RGB (instead of the more typical YUV used for video), but modern video cards will output just about *ANYTHING* as far as the field/frame structure goes.
Remember, various VGA resolutions used to be interlaced, back in the day (when RAMDACs and monitors couldn't support the higher frequencies required for progressive at high resolutions).
- -- Charles Steinkuehler charles@steinkuehler.net
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Luke-Jr wrote:
Yes.
eg, draw the screen field-by-field in a viewable fashon?
Um...actually what a modern (ie: flat-panel LCD or plasma) monitor does is dump the incoming data into an internal frame-buffer that is then scaled to the monitor's native resolution (there are *VERY* few "HD" flat panels that actually have 1920x1080 pixel resolution), in the process kind of glossing over any interlace issues.
There are odd interlace artifacts from this conversion that you won't see on a classic "tube" display (the reason I have a real CRT display next to me right now for testing), and of course interlace itself has it's own artifacts. Anyway, from the layman's perspective, it "just works", eg: draws the screen *FRAMES* in a viewable fashion.
The details of exactly how this happens varies from monitor to monitor, but pretty much all displays other than classic CRTs (eg: LCD, plasma, DLP) will be de-interlacing, and likely scaling and frame-syncing the input signal to match the native pixel resolution and display rate (typically 59.94 or 60 Hz for North American equipment).
- -- Charles Steinkuehler charles@steinkuehler.net
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Charles Steinkuehler -
Jason D. Clinton -
leland sindt -
Luke-Jr