[mythtv-users] MacOSX frontend & 1080i

Andrew Kimpton awk at awkward.org
Wed Mar 14 00:26:11 UTC 2007

Todd Ignasiak wrote:
> On 3/13/07, Andrew Gallatin <gallatin at cs.duke.edu> wrote:
>>> Also, I doubt the LCD is being run at 150Hz, where does Myth show
>>> that?   I think LCDs are set to 60Hz by default, although it's hard to
>>> tell for sure.   I installed SwitchResX control panel & output the DDC
>>> data for the display, and it showed it was running 1440x900 @ 60Hz.
>> It is reported (for me) when using -v playback:
>> 2007-03-12 09:52:04.014 VideoOutputQuartz::GetRefreshRate() [returning 150]
> Hmm,.   I grep'd my log for that, and it is also returning150.  So, I
> looked in videoout_quartz.cpp, and it looks like 150 is the value it
> uses if it doesn't get a valid refresh rate:
>     // Find the refresh rate of our screen
>     CFDictionaryRef m;
>     m = CGDisplayCurrentMode(data->screen);
>     data->refreshRate = get_float_CF(m, kCGDisplayRefreshRate);
>     if (data->refreshRate == 0.0)    // LCD display?
>         data->refreshRate = 150.0;   // Divisible by 25Hz and 30Hz
>                                                            // to
> minimise AV sync waiting
> I'm not sure how that effects playback, but it seems to be the
> expected behavior for LCDs, and playback is okay on mine.  So, I would
> guess this is not the issue.
I agree - it's not entirely clear what the intent of that 'magic value' 
is. Remember though that this is only used when CoreGraphics doesn't 
return a rate - and that only happens for devices such as notebooks and 
the iMac which have an integral display panel with an entirely digital 
connection between graphics adaptor and panel. For external LCD Displays 
connected through a VGA connection kCGDisplayRefreshRate is 'spoofed' to 
being 60 Hz.

I think (from dim memory of practical experiments) that changing that 
150 value to 60 makes no difference - in fact it may make so little 
difference that Andrew G's problems won't go away either. But it might 
be worth a shot for someone to change it and repeat the build.

Andrew 8-)

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