[mythtv] Enabling MMX on MacOS X Intel builds

Todd Ignasiak ignasiak at gmail.com
Thu Mar 23 22:27:23 UTC 2006


On 3/23/06, usleepless at gmail.com <usleepless at gmail.com> wrote:
> Hi,
>
> pardon my curiousity.
>
> On 3/22/06, Todd Ignasiak <ignasiak at gmail.com> wrote:
> > I patched the MMX stuff in the 0.20 SVN tree, and was able to build a
> > frontend binary.  The MMX made a huge difference in the MPEG2 decoding
> > performance, taking it from ~150% CPU to 85-95% CPU on a core duo Mac
> > Mini.
>
> what kind of stream are you talking about? ( Mbs, source? )

That was an ATSC broadcast, captured via QAM256 from my Comcast cable
provider.  The content was 1080i from HD video cameras (60
fields/sec).

~ 95-98% -- 1080i from video source, college basketball program
~ 85-95% -- 1080i from film source, "The West Wing"
~ 70-76% -- 720p from film source, "Lost"

I don't currently have any 720p60fps video material to test with. 
But, I guess it would be a bit higher CPU usage than the 24fps film
sourced material.   I don't have bit rate stats on any of the streams.

> is the playback flawless?

I haven't been using it long enough to give a good analysis.  But, it
has looked pretty good so far..  on par with my Linux frontend with an
Nvidia FX5200 card.

I noticed a bit of judder with "The West Wing", but that may be from
the broadcase, as my local NBC broadcaster has been tweaking their
encoder.   I also saw a couple instances of tearing with the 720p
material,  but only a couple times in the one hour program.

I need to view more broadcasts, and compare Linux vs. Mac output..

> do you have other clients than the Mac ( ie a linux client ), to
> compare the performance?
>
> is the videooutput Xv? do you have mplayer running as well? what kind
> of load does mplayer take?

No, it's using MacOS video APIs, not X11/Xv.     I have an Intel
binary of VLC, and it uses quite a bit less CPU than myth, I think it
was around 55-65% for 1080i.


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