[mythtv-users] trouble with nvidia and bob x2 deinterlacing

[Inor Kuo]

I have searched for and read every thread I could find on bob deinterlacing
but I am still experiencing significant shaking or jitter when using bob x2
with sd and hd recordings (NTSC).  Originally I was using a modeline I found
in the mythtv wiki for my tv and the refresh rate came out to just under 60
so myth wouldn't use bob x2.  In my reading I had come across threads where
people suggested using xvidtune to adjust the modeline so that the refresh
rate was just over 60.

 

Modeline from wiki        "1368x768 at 85" 85.50 1368 1414 1526 1798 768 771
777 795 +hsync -vsync

Modeline tweaked         "1368x768 at 85" 85.50 1368 1400 1720 1792 768 783 791
795 +hsync -vsync

 

Xvidtune wouldn't let me adjust on the fly so I used a modeline calculator
http://xtiming.sourceforge.net/cgi-bin/xtiming.pl and put in my tv's specs
and made adjustments until the refresh rate was over 60.  after a reboot
with my tweaked modeline in xorg.conf, xvid showed the following.

 

Pixel Clock: 85.50 MHz

Horizontal Sync: 47.71 kHz

Vertical Sync: 60.02 Hz

 

My tv is a Vizio 50" Plasma that I got from Costco about almost 2 years ago.
The specs from the manual are as follows.

 

Resolution          Refresh (Hz)       H.Freq (kHz)       V.Freq (Hz)
H.Sync  V.Sync  Pixel Freq (MHz)

1366x768             60                           47.7
60.00                     P             N             85.500

 

At this point, myth let me use bob x2 but like another user reported here
http://www.gossamer-threads.com/lists/mythtv/users/310039?do=post_view_threa
ded#310039, it looked like there was an earthquake going on, moreso for sd
than hd recordings.  

 

I am running mythtv version 0.21 compiled from source on Ubuntu 7.10 Gutsy
with an onboard Nvidia GeForce 6150 gpu using nvidia driver version 169.12,
1gb of ram, 2gb of swap, and an Amd Athlon 64 X2 Dual Core 4200+ processor.
The plasma tv is connected to the computer via vga.

 

Nvidia settings

0/OpenGLImageSettings=1

0/XVideoTextureSyncToVBlank=1

0/XVideoBlitterSyncToVBlank=1

0/XVideoSyncToDisplay=1

 

In mythfrontend, I have "enable OpenGL vertical sync for timing" checked.  

 

I have a total of 3 combined frontend backend machines and I tried getting
bob x2 to work on the other two as well with the same shaky results.

 

                                Monitor
GPU                                       Nvidia Driver      Processor

Setup 1                 50"P50HDTV Vizio Plasma TV      onboard nvidia 6150
169.12                   AMD Athlon 64 X2 Dual Core 4200+ 2.2ghz

Setup 2                 42"GV42L Vizio LCD TV                   onboard
nvidia 6150       1.0.9639               AMD Athlon 64 X2 Dual Core 3800+
2.0ghz

Setup 3                 19"Samsung 920NW LCD               nvidia geforce
7300LE     100.14.19             Intel Core 2 Duo 6420 2.13ghz

 

On all 3 machines I had to adjust the modelines to get the refresh rate
above 60 using the native resolutions of the screens (although 1368x768 was
the closest I could get to 1366x768 for the 2 vizio's).  

 

I've read that there is some jitter to be expected with bob x2 enabled but
what I am seeing is unwatchable for sd recordings.  It's better on hd
recordings but it gives you a headache after a while.

 

I would really like to get bob working correctly but I am fairly new to all
of this deinterlacing and refresh rate stuff.  I feel that I have done as
much as I can on my own and at this point I don't know what else to do so
I'm turning to the community for help.  If anyone can offer any suggestions
it would be greatly appreciated.

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