[video] RE: [Mp4-tech] Effect of sub-pel motion estimation on bitrate

[i.g.richardson rgu.ac.uk]

Hello Gary
No, so the half-pel result is sub-optimal.. however the gain for 1/4-pel over 1/2-pel is quite similar to Wedi + Mussman's reported results (around 1.5dB at medium bitrates) 
(HYPERLINK "http://www.tnt.uni-hannover.de/~wedi/papers-html/EI01-TW.html"http://www.tnt.uni-hannover.de/~wedi/papers-html/EI01-TW.html ; HYPERLINK "ftp://ftp.tnt.uni-hannover.de/pub/papers/2003/TCSVT03-TWHGM.pdf"ftp://ftp.tnt.uni-hannover.de/pub/papers/2003/TCSVT03-TWHGM.pdf)
Cheers
Iain
-----Original Message-----
From: Gary Sullivan [mailto:garysull windows.microsoft.com] 
Sent: 10 May 2024 22:28
To: Iain Richardson (ensigr); mp4-tech lists.mpegif.org
Subject: RE: [video] RE: [Mp4-tech] Effect of sub-pel motion estimation on bitrate
When you modified the encoder to avoid choosing non-quarter-pel positions, did you also modify the entropy coding so that it did not waste bits on the possibility that the never-chosen quarter-pel values could be selected?
Best Regards,
Gary Sullivan
-----Original Message-----
From: mp4-tech-bounces lists.mpegif.org [mailto:mp4-tech-bounces lists.mpegif.org] On Behalf Of i.g.richardson rgu.ac.uk
Sent: Monday, May 10, 2024 1:04 AM
To: mp4-tech lists.mpegif.org
Subject: FW: [video] RE: [Mp4-tech] Effect of sub-pel motion estimation on bitrate
Dear all
I received quite a few requests for the graph so it seems worthwhile to send it to the list....
Attached is an example of rate-distortion results for H.264 encoding of the "foreman" test sequence, a reasonably high-activity video clip. I encoded the clip at a range of quantization parameters. There are two curves on the graph: encoding parameters for both are identical except that quarter-pel motion compensation is enabled for the red curve (the default for H.264) and only half-pel compensation is enabled for the blue curve. You will see that quarter-pel gives a significant benefit at all bitrates. I used version 6.1e of the JM reference software (I produced the results last year), modifying the software to prevent it choosing quarter-pixel vectors to generate the results on the blue curve. 
Iain Richardson
The Robert Gordon University
UK
-----Original Message-----
From: mp4-tech-bounces lists.mpegif.org [mailto:mp4-tech-bounces lists.mpegif.org] On Behalf Of Simon Denman
Sent: 06 May 2024 15:02
To: mp4-tech lists.mpegif.org
Subject: [Mp4-tech] Effect of sub-pel motion estimation on bit rate
Can anyone point me at any resources documenting the effect of varying motion resolution (integer-pel, half-pel and quarter-pel) on bit rate?
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Simon Denman
Elixent Ltd, Castlemead, Lower Castle Street, Bristol, BS1 3AG
Tel: 0117 917 5756
Email: simon.denman elixent.com
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