[mythtv-users] 0.24 Mac OS X Build

TJ Harris tjharris at weaselworkz.com
Wed Mar 23 15:51:07 UTC 2011

On Mon, Mar 14, 2011 at 12:01 AM, Nigel Pearson <nigel at ind.tansu.com.au> wrote:
> On Thu, 10 Mar 2011, TJ Harris observed:
> - Top CPU user in both 1080i and 720p was mmx_i420_2vuy  color
> conversion.  Kind of surprising that it isn't done in hardware.
> Used to be. In late 2004, Jeremiah worked out how to get QuickTime
> to do it in hardware, and the code was in there until late 2006,
> when Mac OS X moved from PPC to Intel hardware.
> The Intel QuickTime code crashed when fed YUV420 data.
> I created an Apple bug ID (4731762), but never got time
> to prove the bug to them. In the end, it was much
> easier to remove the QuickTime colour conversion.
> (made the code simpler, and any Core Duo CPU had
>  ample grunt to SW convert). Haven't re-visited that bug.
> Not sure how OpenGL does it.
> - nvChannel::waitForTimeStamp  was present on both, but much higher
> CPU usage at 720p (2.8% vs 0.8%)
> Hmmm. I don't know what is invoking that (not our code).

Yeah, it looks like it's related to the Nvidia video driver/libraries.
 Shark showed it as in an "Unknown Library", but also identified it as
GeForce at some levels.

Both my Mini and my MBP have Nvidia video.    Although, I do have an
older MBP which I think has a Radeon GPU.  I'll give that a try to see
if it behaves any differently there (which would be interesting, but
not helpful unless it helps to narrow the problem down.. I think Mac
Mini is the primary MythTV platform of interest).

> Does running an external (CRT?) display
> at different refresh rates affect this?

I don't have any CRTs to test with.  But, it behaves the same way on
internal LCD and external projector (DVI->HDMI-> DLP Projector @ 720p)

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