[mythtv-users] [ G400 ] Hotwo enable flicker filters

[Cory Papenfuss]

> o.k  i think i will try this.
>
 	I doubt it will work, but you never know.

> Hm, maybe this isn't an idea that is realizable. I thought of enabling and 
> disabling flicker filter while X is running.
>
 	I think I get what you're trying to do now, and I'm pretty sure it 
won't work.  If you're using the SCART cable, then tvout isn't used.  The 
flicker filter on the card will be an option on the tvout chip, not on the 
VGA output (second head, even).  Now, it's slightly possible that it 
will work, since it's a matrox with an adapter kind of setup.  What you're 
really doing is using the tvout function, but tapping off RGB directly. 
You're treading on Matroxisms here, so I've no idea.

> The TruType fonts dosn't look so bad. Problem are the on lined borders around 
> the selection lists in mythmusic and mythvideo. Someone wrote in an other 
> thread about simply bluring all images from the mythtv-theme. This works for 
> the buttons. But the line around the selection list seems to be generated by 
> mythtv itself. So bluring the theme dosn't help.
>
 	Again, it seems like it would be a worthwhile project to fixup the 
GUI of MythTV to do this.  If it's drawing lines, then maybe either double 
or triple (...0%-0%-50%-100%-50%-0%-0%...).  I guess that's what apple 
used to call their "Convolution flicker filter."

> - has two heads, first is accelerated and seconed has tv-out but is not
>  accelerated
> - the original Matrox driver for X supports accelerated first head and tv-out
>  on seconed head. Problem is: Not both at the same time, on one head. This
>  menas: I wasn't able to get accelerated video on tv.
> - workaround: Using the kernel matroxfb which clones first head to seconed 
> head.
>  X runs with the original Matrox drivers but with the "UseFBDev" option
>  enabled. So i'm not able to use the heads seperately 'cause both heads show
>  all the time the same image but i'm able to get accelerated video on tv.
>
 	It sounds like a mess.  Keep in mind that there are different 
kind of "accelerated" video.  I'm sure someone who knows more can correct 
errors, but normal accelerated video just has to do with the vid card 
doing DMA on chunks of memory, as well as drawing lines, etc with 
primitives and not having to have it's bits calculated and manually 
entered into the VRAM by the CPU.  The more applicable acceleration for 
MythTV is whether or not the card can do hardware-accelerated color 
transformations and scaling... called Xv for XVideo.  It's almost a 
necessity for making video playback not chew up a bunch of CPU.

> Please note: I'm using the VGA to SCART cabel as described on
> http://www.myhtpc.de/showtopic.php?threadid=1214
> connected to the seconed head of the G400. (The page is in german but the 
> important thing, the circuit, is shown in an image.)
>
 	Funky.  Again, it looks like a matroxism.  I would seriously 
consider ignoring this oddball contraption and just use a regular VGA type 
of SCART connector such as:

> I know about the other VGA to SCART cable as described on
> http://www.sput.nl/hardware/tv-x.html

 	You don't need the transistor garbage though.  All that's doing is 
combining HSYNC and VSYNC into a composite CSYNC.  The Matrox cards (as 
well as some, but not all others) can do CSYNC with a driver flag. 
Generally, its done by adding "+csync" or "-csync" at the end of the 
modeline, IIRC.

> but this didn't worked for me. Maybe i do not exactliy know how to use this 
> with
> my G400. Where it will be connected? First head, seconed head? Do i need the 
> kernel matroxfb? Which drivers i've to use? Original Matrox or Xorg mga? I 
> remember trying to use the G400 without the kernel matroxfb in combination 
> with the original Matrox X driver. But i didn't find any modline which was 
> accepted.
> Especially the recommended PAL mode
> "736x575i" 14.16 736 760 824 904 575 580 585 625 interlace -hsync -vsync
> was not accepted.
>
 	This is the way to do it, but I don't think I believe your 
modeline.  Isn't PAL 768x575?  The above is only 736 so it's going to 
force scaling.  A bit of quick math can convert the fb.modes timing into 
an Xorg timing.  The one you said before seems good:

mode "768x576-50"
     # D: 14.766 MHz, H: 15.625 kHz, V: 50.001 Hz
     geometry 768 576 768 576 32
     timings 67723 106 1 44 1 70 4
     csync high
     bcast true
     laced true
     accel true
     rgba 8/16,8/8,8/0,8/24
endmode

 	Doing some conversion, the following modeline follows from the 
above data:

Modeline "corypali" 14.766 768 769 839 945 576 577 581 625 interlace -csync

 	Do a 'man fb.modes' to see how to interpret the fb.modes style of 
defining a modeline.

 	If you get an "Hsync out of range" in your /var/log/xorg.conf when 
you try this, you probably need to change the hsync range of your monitor 
to be 15kHz minimum.  Most likely it's 31kHz minimum now.  That's why it 
didn't work before.

-Cory

*************************************************************************
* Cory Papenfuss                                                        *
* Electrical Engineering candidate Ph.D. graduate student               *
* Virginia Polytechnic Institute and State University                   *
*************************************************************************