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

Inor Kuo inorkuo at hotmail.com
Wed Mar 19 19:49:03 UTC 2008


>> 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://xtimingsourceforge.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_threaded#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 Version     Processor
>> Setup 1 50'P50HDTV Vizio Plasma onboard nvidia 6150 169.12 AMD64X2 DC 4200+2.2ghz
>>
>> Setup 2 42'GV42L Vizio LCD TV     onboard nvidia 6150 1.0.9639 AMD64X2 DC 3800+2.0ghz
>>
>> Setup 3 19'Samsung 920NW LCD nvidia geforce 7300LE 100.14.19 Intel C2D 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.
>
>
>
> Inor,
>
> You're probably on the right track... I suggest you take one box and
> do a scientific approach only changing one setting at a time.
>
> First of all you need to get some debugging going however:
>
> mythfrontend -v playback>/tmp/frontendlog 2>&1
>
> should provide you with some nice logs.
>
> Check that you are indeed using bob deinterlace (it'll say so in the
> logs). That myth has recognized the refresh rate correctly etc...
>
> My personal idea is that you might need to turn off 'enable OpenGL
> vertical sync for timing' .
>
> Cheers
>
> Steve

Logfile# 2

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