Hi

I have setup R5A26 on an old Intel i810E Mobo as a first foray into Mythtv.
Have got to the stage where I can watch live TV, schedule + record shows, etc. All good so far on what's really old hardware (800 MHz PIII).

I'd like to connect the Mythtv box to a regular TV set, instead of using a video card with TV out, I'd rather use the VGA connector to connect to a SCART connection on the TV, as documented on this link

http://www.sput.nl/hardware/tv-x.html

The old i810E Mobo does not have an AGP slot + I'd like to keep the hardware count down to the minimum & also keep the setup low profile, as I have a small case in mind. I built the circuit from the link, but can't seem to find an i810 modeline that works for PAL TV.

I need to use 800x600@50Hz vertical, 15.625KHz horizontal,interlaced.

Have spent the last few weeks searching for info on the i810e, have got the Intel programmers reference manual (which does seem to indicate it can support these sync frequencies). I've tried a lot of modelines from Google, but most seem to be ignored (get bad clock mode/interlaced/doublescan entries in XFree86.0.log).

To check the circuit works, I have another Mobo with a Chips 'n Tech 69000 graphics chip & have used the circuit with this Mobo successfully on the TV (NOTE: am using Win98 on this Mobo, but have a small EXE to enable the TV support built into the Mobo video bios). So the circuit definitely works as long as the VGA port is set to the correct sync frequencies.

Since there is no special TV out circuitry on the i810e Mobo (need a few extra devices), there is a possibility the video bios does not support TV modes. However, it should be possible to program it using modelines.

Has anybody else done anything like this with Mythtv?
Anyone got any ideas on where to start?

Regards
Gerry

More info:

Loaded R5A26 onto the Mobo with the Chips 'n Tech 69000 graphics chip.
Was not able to get TV compatible signals, even though the board has a built in TV compatible mode in the Vbios. Mythtv did recognise the chipset.

Went back to the i810E Mobo, decided to alter the monitor horizontal & vertical refresh ranges. Got more built in modelines to work. Added a few TV compatible modelines into XF86Config-4, but these are marked as bad when X starts up (looked at /var/log/XFree86.0.log).

At this stage, it appears the i810 driver will not allow custom modelines, it only allows valid default modelines (presumably found in the Vbios).

Am I correct in this assumption?

It also marks loads of the default modes as bad.

Went back to using xvidtune, started with a 640 x 480 mode & adjusted the hsync down to near TV frequencies (~15.625 KHz), but could not get the vsync near 50Hz. Plugged in the TV anyway, saw a messed up picture, but it was better than previous attempts.

Looks like it really is possible, but only if the Pixel clock is reduced to something like 14~15 MHz (as in most of the modelines found by Google).

I thought about trying 855resolution, but I am unsure if this only works for 855 & newer graphics devices & also I think it only alters the size of the screen, not the horizontal/vertical refresh rates.

Guess the only way to be sure is to try it!!
If it does not work, next thing to try is to replace one of the Vbios modes with a custom mode, but I don't know if it's do-able for the i810.

If all else fails, directly manipulating the N,M & P registers on the chip might get it working.

An interesting idea, I had no idea you could even do that!

I'm sure my old i810 motherboard with on board VGA had a tv out header on the mobo, so surely the chip can produce the right modes?

Perhaps try using nvtv. There is mention of I810 in its doco.

I don't think all of the i810 motherboards had the TV out hardware installed. I read somewhere about a chip by Chrontel (possibly there are variants) which is required for PAL or NTSC tv out.
I think that may be what made enabling tv out difficult on i810 drivers, there are many different Chrontel chips, all with different init requirements.

I read on the intel 82810 programmers guide the pixel clock is supplied by the TV out hardware when in TV out mode, clock varies from 20 to 40 MHz, depending on mode. However, the Chrontel chip (& others of it's type) are just needed to convert RBG signals + combine the hsync & vsync into a composite video output (possibly S-VHS also).

For TV's with a scart socket, composite is a step backwards. Scart sockets accept RBG (well most do RBG + composite) PAL TV's can manage 800x 800. Converting the VGA hsync & vsync to composite sync is easy, wiring a vga plug to a scart lead is also easy. Problem is getting the video card to produce a hsync frequency low enough for TV.

I think there are many cheap VGA cards that can doe 640 x 480 & clock low enough for TV, getting 800x600 is a bit harder.

Also, I'd like to use the accelerated drivers rather than the VESA drivers.
So far, the i810 driver seems reluctant to use any custom modeline, it sticks to what are reported by the Vbios + what the monitor can accept.
disabling the monitor detection does not get extra modelines.

OK, might try this.

Tonight, I loaded ubuntu onto the PC, am trying this because it has xorg, & I think there may be enhanced i810 drivers. So far I am running into the same problems, driver won't seem to allow custom modelines.

This is annoying, as I know the 82810 chip can clock down to 12 MHz (reported in XFree86.0.log) so I don't know why it is restricting itself to bios modes. Will have to look at the i810_drv source.

I encourage you to look at nvtv. If it works for I810 as well as it does for geforce2, it is an extremely flexible and powerful tool.

Ok, I had seen this, & assumed it only works with Nvidia cards, however, a quick look at the home page forums seems to indicate it has some level of i810 support built in. I'll try it, I am not hopeful of results because this SW is intended to be used on cards which have TV encoder chips, my motherboards does not have any.

If I'm lucky, nvtv might set the syncs correctly for TV out on the VGA port also, which is exactly what I want (assuming RGB is still presented at the VGA port while in TV mode). Can't hurt to try, I guess.

Perhaps it can provide an interface to the 82810 registers

Did have some success last night with ubuntu & a motherboard with a Chips & Tech CF69000 graphics chip, managed to get reasonable PAL TV out from the VGA port using a modeline. I widened the hsync & vsync ranges in xorg.conf, commented out DDC & now the modeline is not rejected. I have to tweak it some more, too much overscan.

Tried the same with the i810 motherboard, did manage to get the modeline accepted, but can't get interlace mode to work.

I need this, without interlace turned on, vsync = 25Hz.
The Chips 'n Tech video device can do interlace, = 50Hz vertical refresh.

Course, this is ubuntu, I'd rather have Knoppix working, will try all this again with R5A26.

Managed to install nvtv on on ubuntu (it complained about not finding libgtk-1.2.so.0, so I installed libgtk2.0-0_2.8.9-2ubuntu2_i386.deb from the ububtu, can't find libgtk-1.2.so.0 anywhere). So far, cannot get the GUI mode working, but it seems to work in command line mode. At least I can query some registers, just need to work out what they are.

However, this is all happening on ubuntu, would rather have Knoppmyth.
Is nvtv available for Knoppmyth?

nvtv is on knoppmyth. I think the version has been patched (and recompiled without the gui). I believe you can just apt-get nvtv to get a version with the gui.

I was able to compile it with the gui after installing a bunch of other things from source (atk, pango, gtk+ and maybe more cant remember).

Had a good look at the ubuntu install of nvtv (command line version only, as there is an error when trying to launch the GUI). I can issue a query & see the contents of some registers, DPLL, DCLK, ODS, etc; but I don't see anyway to change these. Read the docs, there is mention of registers & changing values, but this seems to be for the GUI version only.
It looks like nvtv supports the i810 somewhat, not sure how much.

Right now, I have a mode that is very near what I need, except the Vsync is 25Hz. I suppose there are a few ways to fix this.

1. Make a BIOS call to set the correct mode - have done this in the past (in Win98) when I needed PAL out. Works great - as long as the video bios supports this mode. I don't think Intel's does, & the i810 driver docs (XFree86) explictly state interlace mode is not supported. The 82810 device does support interlace mode.

2. Use a modeline in nvtv to get close enough to what I want, then write to SVGA register CR70 (interlace on/off + CRT half line register).
This might work, as long as that's all I need to do. Would like to use nvtv if it's able to write these registers, so I'll need to compile or get the GUI version.

3. Forget about interlace mode & try to get the vsync rate to 50Hz.
This won't be easy, as vsync is tied to Horizontal & Vertical timing parameters.

4. My TV is supposed to be able to do progressive scan (525p/60Hz), not sure if it can manage 625p/50Hz. I suppose I could make a 60Hz modeline, see how it looks.

Will test Knoppmyth over the weekend with nvtv

Did an apt-get update + apt-get install nvtv tonight.
Restarted box before testing.
Typing "nvtv" in an xterm (as root) gets a segmentation fault.
Typing nvtv -n gets a nice GUI!

Tried a few of the settings, it's possible to select i810 as the chipset & see some register values. Unfortunately, the Non-Interlaced flag appears to be the setting on the TV-out chip rather than the VGA register (CR70).
Changing it has no effect on my display.

Can use nvtv to change modes, this is way easier than manually hacking XF86Config-4. I'll use this in future. Thanks for the tip Greg
Still looking for a way to set the interlace bit.

Managed to contact one of the i810 driver maintainers, who although not able to tell me why interlace mode does not work, made some suggestions as to where to look in the code. This won't be a quick fix, so now looking at other options (different video card, maybe one with TV out).

Go for an FX 5200. You can get them really cheap, and they do a good job of svideo out. Some of them are fanless=quiet and some have DVI outputs paving the way to high def if you want to go that way in the future.

Yeah, not a bad choice, they are reasonably cheap.
Don't think I can get one with PCI, & the motherboard has no AGP socket.
I suppose if I was only going to use the mythbox for TV viewing, a PCI card might be enough, I don't need 3D.

Right now, the i810 motherboard is doing a good job with playback, but it's really holding back the show with the lack of expansion options.
I might be better off looking at one of those ITX boards with built in TV out.

I built the box to get some idea of Mythtv's capabilities, so far I am impressed, I'd really need to try it out in a "live" situation, see if it works well enough to justify buying hardware to make a fully featured HTPC.