[XviD-devel] Qpel Problem Samples

j_coleman at shaw.ca j_coleman at shaw.ca
Thu Sep 4 22:55:45 CEST 2003


It was mentioned on the doom9 forums by Isibaar that if we came across some 
samples where qpel performed worse than half pixel (ie lower PSNR) that we 
could put them online and post a link.  I posted this on doom9 but I don't 
know if any of you guys have seen it yet.  So anyway here are the source 
files that I have found that when encoded with qpel exhibit a lower PSNR.  
Probably though I should say something about how they were encoded first.  
All three files were force-filmed to 23.976fps in dvd2avi and this avs script 
was used or something similar: 

LoadPlugin("C:\Program Files\Avisynth 2.5\plugins\Mpeg2dec3.dll")
Mpeg2Source("C:\TERMSE_SIDEA\VIDEO_TS\terminatortest.d2v")

They were then loaded into virtualdubmod and encoded with a dev-api-4 build 
from August 19th built with ICL7.0 just a win32 release, only default options 
were used except of course for qpel.  All encodes were two pass and PSNR 
measurements were performed with psnr4avi.  Anyways here are the results:

For a short clip aiming for 2MB:
with qpel: Average PSNR (Y U V): 43.26, 45.70, 45.76 Average PSNR: 44.91
without qpel: Average PSNR (Y U V): 44.18, 45.86, 45.96 Average PSNR: 45.33
And here is the url for the source file http://www.geocities.com/bonzi5252/..
.atorsample2.zip

For another short clip again aiming for 2MB:
with qpel: Average PSNR (Y U V): 44.15, 48.54, 49.01 Average PSNR: 47.23
without qpel: Average PSNR (Y U V): 45.15, 48.67, 49.13 Average PSNR: 47.65
Source file can be found here http://www.geocities.com/bonzi5252/bondsample.
zip

And one more clip aiming for 350KB:
With qpel: Average PSNR (Y U V): 45.26, 48.94, 49.09 Total Average PSNR: 47.
76
without qpel: Average PSNR (Y U V): 45.94, 48.98, 49.14 Total Average PSNR: 
48.02
And the source file http://www.geocities.com/bonzi5252/bondsample2.zip

If you need more samples or if these ones are completely useless, don't 
hesitate to ask or comment.



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