[mythtv] Choppy performance on Mac Intel builds / scaling issue?

[James Mitchell]

In contrast to some other reports of good 1080i performance
via the MMX enabled builds of 0.19, I'm experiencing issues
with both 1080i content, and scaled 480i content.

I'm getting very choppy performance on a 1.66GHz core duo 
with the MMX enabled binaries linked from:

http://www.mythtv.org/wiki/index.php/Myth_on_Mac_x86 

This applies to both 1080i content, and scaled 480i content, 
which I found pretty strange. For comparison, the latest 
trunk builds of VLC play these same files perfectly over 
the network, so the machine is clearly capable.  
Interestingly, if I turn off 'Scale Video as Necessary' in 
TV Settings->Playback, then the problem goes away, at least 
for the 480i content. There is a corresponding impact to 
the profile information that Shark reports. The difference 
appears to be the YUV422_UC_ToRGB32BitColorBGRA 
QuickTimeComponents function, which is the primary consumer 
of cycles in everything except the '480i, do not scale 
video' case. Checking/unchecking the scale video setting 
has no effect on the performance of 1080i playback.

The function in question is called out of libmythtv 
VideoOutputQuartzView::Show(), and appears to be seperate 
from the non-optimized yuv420-2vuy colorspace conversion 
within the libmythtv code that some have mentioned.

Is anyone else seeing this effect? Any ideas on what might
be done to address it?

I've included some of the Shark output from different test
scenarios:

Shark Time Profile of Mythfrontend Intel MMX build playing 
1080i content at 1920x1080 on core duo 1.66GHz mac mini

26.5%	26.5%	QuickTimeComponents YUV422_UC_ToRGB32BitColorBGRA
18.7%	18.7%	mythtv	non_vec_yuv420_2vuy(unsigned
		char*, unsigned char*, unsigned char*, unsigned char*,
		int, int, int, int, int)
8.8%	8.8%	mythavcodec mpeg_decode_mb	
5.3%	5.3%	mythavcodec ff_simple_idct_add_mmx
3.8%	3.8%	mach_kernel ml_set_interrupts_enabled
3.4%	3.4%    mythavcodec put_pixels16_xy2_mmx
3.3%	3.3%    mythavcodec put_pixels16_mmx	
2.9%    2.9%    mythavcodec MPV_decode_mb	
2.9%    2.9%    mythavcodec put_pixels8_mmx	
1.9%    1.9%    mythavcodec ff_simple_idct_put_mmx 
										Shark Time Profile of Mythfrontend Intel MMX build playing 
480i content at 1920x1080 (With TV Settings->Scale Video 
as Necessary checked) on core duo 1.66GHz mac mini 

11.9%	11.9%   mach_kernel ml_set_interrupts_enabled 
5.4%    5.4%    mythtv non_vec_yuv420_2vuy(unsigned 
                char*, unsigned char*, unsigned char*, 
		unsigned char*, int, int, int, int, int) 
3.2%    3.2%    mythavcodec mpeg_decode_mb	
2.5%    2.5%    mythavcodec ff_mpa_synth_filter	
2.1%    2.1%    mythavcodec ff_simple_idct_add_mmx 
1.3%    1.3%    mythavcodec put_pixels8_mmx	
1.0%    1.0%    AudioToolbox Resampler2::ConvertAltivec(float*, 
                float*, unsigned long, int) 
1.0%    1.0%    mythavcodec put_pixels16_mmx	
0.9%    0.9%    mythavcodec MPV_decode_mb	
0.7%    0.7%    mythtv AvFormatDecoder::MpegPreProcessPkt(AVStream*, 
                AVPacket*) 
0.6%    0.6%    mythavcodec put_pixels16_xy2_mmx 
0.5%    0.5%    mythavcodec MPV_motion	

Shark Time Profile of Mythfrontend Intel MMX build playing 
480i content at 1920x1080 (With TV Settings->Scale Video 
as Necessary unchecked) on core duo 1.66GHz mac mini 

23.9%   23.9%   mach_kernel ml_set_interrupts_enabled 
9.5%    9.5%    mythtv non_vec_yuv420_2vuy(unsigned char*, 
                unsigned char*, unsigned char*, 
		unsigned char*, int, int, int, int, int) 
7.8%    7.8%    commpage [libSystem.B.dylib] __memcpy 
6.9%    6.9%    mythavcodec mpeg_decode_mb	
5.9%    5.9%    mythavcodec ff_mpa_synth_filter	
4.8%    4.8%    mythavcodec ff_simple_idct_add_mmx 
3.2%    3.2%    AudioToolbox Resampler2::ConvertAltivec(float*, 
                float*, unsigned long, int) 
2.1%    2.1%    mythavcodec put_pixels8_mmx	
1.8%    1.8%    mythavcodec put_pixels16_mmx	
1.8%    1.8%    mythavcodec MPV_decode_mb	

Here's the call tree for how mythtv reaches the expensive 
Quicktime function: 

27.2%  QuickTimeComponents YUV422_UC_ToRGB32BitColorBGRA 
0.0%   QuickTimeComponents FinalGlueBeforeTheBlit 
0.0%   QuickTimeComponents PrepareForBlitThenDoBlit 
0.0%   QuickTimeComponents ScalingCodecComponentDispatch 
0.0%   CarbonCore CallComponentDispatch 
0.0%   QuickTimeComponents ImageCodecDrawBand 
0.0%   QuickTimeComponents BaseCodec_DecompressWorkFunction 
0.0%   CarbonCore InvokeComponentMPWorkFunctionUPP 
0.0%   QuickTimeComponents BaseCodec_DecompressCallBack_Common 
0.0%   QuickTimeComponents Base_CDBandDecompress 
0.0%   CarbonCore CallComponentFunctionCommon 
0.0%   QuickTimeComponents Base_CDComponentDispatch 
0.0%   QuickTimeComponents ScalingCodecComponentDispatch 
0.0%   QuickTimeComponents YUV422CodecComponentDispatch 
0.0%   CarbonCore CallComponentDispatch 
0.0%   QuickTime ImageCodecBandDecompress 
0.0%   QuickTime DoBandedDecompress 
0.0%   QuickTime ICMAction	
0.0%   QuickTime ICMDeviceLoop	
0.0%   QuickTime DecompressSequenceFrameWhen 
0.0%   mythtv VideoOutputQuartzView::Show()

Thanks,

James