HTPC linux hardware gotchas

[TechMage89]

Is this just a matter of plugging a modeline into randr? Or do there need to be modifications to the modesetting code?

I'm not one of the fortunate ones with a 120hz TV, so I can't check this myself.

[mirak63]

you don't need a 120hz tv, mine is not

just changing modelines doesn't work, it seems Xorg or the open source drivers resist to beeing put into 24hz

I would say it's about the driver, since nvidia and fglrx manage to do 24p

[agd5f]

you don't need a 120hz tv, mine is not

just changing modelines doesn't work, it seems Xorg or the open source drivers resist to beeing put into 24hz

I would say it's about the driver, since nvidia and fglrx manage to do 24p

It should respect the modeline you specify. There's no code (in radeon at least) to not accept 24p modes. What happens when you try and specify one with xrandr?

xrandr --newmode <24p modeline>
xrandr --addmode <output> <24p mode name>
xrandr --output <output> --mode <24p mode name>

e.g. (change the output and mode bits to your setup),
xrandr --newmode "1920x1080_24.00" 63.00 1920 1976 2160 2400 1080 1083 1088 1098 -hsync +vsync
xrandr --addmode DVI-0 "1920x1080_24.00"
xrandr --output DVI-0 --mode "1920x1080_24.00"

[mirak63]

It should respect the modeline you specify. There's no code (in radeon at least) to not accept 24p modes. What happens when you try and specify one with xrandr?

xrandr --newmode <24p modeline>
xrandr --addmode <output> <24p mode name>
xrandr --output <output> --mode <24p mode name>

e.g. (change the output and mode bits to your setup),
xrandr --newmode "1920x1080_24.00" 63.00 1920 1976 2160 2400 1080 1083 1088 1098 -hsync +vsync
xrandr --addmode DVI-0 "1920x1080_24.00"
xrandr --output DVI-0 --mode "1920x1080_24.00"

I tried by adding modelines directly in xorg.conf and it didn't worked.
At best Xorg and xvidtune showed it was in 48hz, however it was like it was in 50hz, with juddering during playback.

[Kano]

That's normal, some TVs use build-in optimizations, also integrated pull-down, so 24 hz is not better than 60 hz. In the cinema you don't see more than 24 pics, but a little trick is used there. You see 2x or 3x the same pic but with black inbetween. That increases the rate from 24 to 72. That trick with black inbetween pictures use some 200 hz models. Don't think using an extra cheap tv with 24 hz will give better results, that's mainly pure optimization in the tv itself how good it will look.

[mirak63]

That's normal, some TVs use build-in optimizations, also integrated pull-down, so 24 hz is not better than 60 hz. In the cinema you don't see more than 24 pics, but a little trick is used there. You see 2x or 3x the same pic but with black inbetween. That increases the rate from 24 to 72. That trick with black inbetween pictures use some 200 hz models. Don't think using an extra cheap tv with 24 hz will give better results, that's mainly pure optimization in the tv itself how good it will look.

my tv is doing real 24p, so does the nvidia and ati proprietary drivers

we don't care how the TV displays it, what we know is that it needs 24hz input, and that proprietary drivers are doing something that the opensource drivers can't

[Kano]

Truth is something else than what you think to know.

[mirak63]

Truth is something else than what you think to know.

If you believe opensource drivers can do it then just show us how.

Any input is welcome, but at this point, theorical asumptions on hardware you don't own doesn't help much.

Even if the TV is doing tricks, obviously and you see that when you do real tests, you need something to enable them, and bridgman said the trick is that the video card output 24hz.

Now for some reason, nv and radeon drivers don't allow me to be in 24hz.

By the way, I guess it's you who banned me from #mplayer-dev ...

[agd5f]

I tried by adding modelines directly in xorg.conf and it didn't worked.
At best Xorg and xvidtune showed it was in 48hz, however it was like it was in 50hz, with juddering during playback.

It sounds like something wasn't configured properly. Can you try the method I suggested or pastebin your xorg log with the modeline you tried to use?

[mirak63]

actually I run windows since hd4850 video drivers sucks
however I think I posted modelines I used here already
I will let you know