[M4IF Technotes] Problem : Half Pixel ME

[Peter Haighton]

Sachin,
The answers to your questions are definitely dependant on implendation
details. Depending on what the ME finds as it's best match will determine
whether or not the file size will increase. This is the case also for full
pixel ME since the best match that you obtain through for example SAD of
macroblocks may not translate to the smallest VLC codes.
Half pixel ME is designed to improve quality of the image but again that is
dependant on many factors. For example, if you find that your ME technique
consistently uses many more bits than full pixel ME, and you are compressing
at a fix rate, you may find that the quality decreases. On the otherhand it
is typical that higher quality is obtained both in PSNR and visually.
Increased Complexity comes right down to a case by case basis on how the ME
is built. There are a few ways of building in half pixel ME with very
different complexities.
Peter
--
Peter Haighton
VideoSpheres Inc.
84 Hines Road
Kanata, Ontario
Canada, K2K 3G3
Tel: (613) 270-9646 x3022
Fax: (613) 271-9442
email: peterh   VideoSpheres.com
See http://www.m4if.org for the latest on MPEG-4
-----Original Message-----
From: technotes-admin   lists.m4if.org
[mailto:technotes-admin   lists.m4if.org]On Behalf Of Sachin Patil
Sent: Thursday, August 08, 2023 5:24 AM
To: technotes   lists.m4if.org
Subject: [M4IF Technotes] Problem : Half Pixel ME
Hello all,
    I have an integer pel search Motion Estimation algorithm implemented
for my MPEG4 video encoder. Now I am trying to refine the search using half
pixel resolution. I find that there is an increase in file size with half
pel refined search.
Can anyone tell me the advantages of using Half Pel search with respect to
the following --
1. I want to know if there can be an increase in the output file size.
2. Is half pel refinement used only for an improvement in quality ( quality
measure used : PSNR ) ?
3. What is the increased computational complexity?
Thankyou,
Sachin.
--
Sachin Patil.
Smart Yantra Technologies Pvt. Ltd.
Bangalore
INDIA
Phone : +91 80 363 4917, 363 4918
Email : sachin   smartyantra.com
Website : www.smartyantra.com
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