[mythtv-users] Mac OS X choppy playback at high display resolutions, such as 1080p

David Snider dsnider at thesniderpad.com
Sat Nov 15 13:53:37 UTC 2008



scram69 wrote:
> On Mon, Oct 29, 2007 at 4:53 PM, Eric Robinson <ryunokokoro at gmail.com> wrote:
>   
>> On 10/10/07, Eric Robinson <ryunokokoro at gmail.com> wrote:
>>     
>>>> I did some quick testing.  It looks like that anytime that the image
>>>> needs to be transformed (offset or scaled) it causes a problem so the
>>>> patch wouldn't solve the problem if you set an overscan or offset.
>>>>
>>>> I don't know of an easy solution that will allow overscan or offset
>>>> without using the QuickTime transform function which seems to be
>>>> causing the problem.
>>>>
>>>> The most likely solution would probably be to move to a CoreVideo/
>>>> OpenGL based VideoOutput class that could utilize the GPU for the
>>>> transformation.
>>>>         
>>> Ahh, so the problem lies in the QuickTime transform function.
>>> Conceivably, though admittedly unlikely, Apple could update QuickTime
>>> and fix the slow speed...?
>>>
>>> The other option sounds like a major shift in the way the video is
>>> processed on the Mac.  Mino, are you a MythTV developer?  Is that
>>> something that is plausible?  Should this be marked as a bug (as 1080p
>>> TVs get more common this will likely affect a lot of people...)?
>>>
>>> Thanks for all the help.
>>>
>>> - Eric
>>>
>>>       
>> As can be seen above, it appears that falling back on QuickTime based
>> functions for image scaling when (VerticalScreenPixels >= 1080) AND
>> (VerticalVideoPixels == 1080) causes hiccuppy gameplay. In Mac OS
>> 10.4.x at least.
>>
>> We now have a new version of OSX to test on, however, with purportedly
>> updated video libraries (?).  Has anyone tested this scenario on
>> Leopard (Mac OS 10.5.x)?  Is the problem still present?
>>
>>     
> Dredging up this old thread as I finally got around to upgrading to 10.5.
>
> Under 10.4.11, using 0.21 OSX universal frontend (not -fixes), I used
> a 1% "overscan" or scaling in the playback settings to remove "bars"
> and black/white noise from around the edge of the playback (displaying
> onto 720p plasma).
>
> When I tried the same 1% overscan under 10.5.5, using 0.21-fixes
> (18900 weekly build), playback really suffers.  I'm using a 2.0 GHz
> core2duo mini.
>
> Has anyone had success using scaling to slightly overfill their
> display under 10.5/0.21-fixes?
>
>   
I'm not scaling because I go straight into the HDMI on my TV.  The mac 
recognizes the TV and overscan's on it's own.   Maybe try that?


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