[M4IF Technotes] Re: Compression Ratio

[William J. Fulco]

Boy I really dislike the term Compression-Ratio...
Not only do you need to know what the target bit rate is - you need to know
what the starting point is... 176x144 (QCID), 320x240 (QVGA), 640x480 (VGA),
1920x1080 (HD)... what frame/field rate  (10fps, 15fps, 29.97fps, 60fps)...
how many bits/pixel to start? YUV422 (16bpp), YUV420 (12bpp), RGB (24bpp),
YUV411 (9bpp).... so if you consider your "starting place" to be
640x480xRGBx30fps and your end-up place to be 1mbps - then your "compression
ratio" is 221:1 - but if your starting place is 640x480xYUV422x30fps then
your "compression ratio" is "only" 147:1 - and if you assume your starting
place is 640x480xYUV420x30fps then your "compression ratio" is 111:1....
When you use the term "compression ratio" - you should immediately wash your
brain out with soap. Grrrrrrrr
++Bill
William J. Fulco
wjf   NetworkXXIII.com
310-927-4263 (Cell)
---------------------------------
 "There are 10 kinds of people in the world:
 those who count in binary and those who don't."
> -----Original Message-----
> From: technotes-admin   lists.m4if.org
> [mailto:technotes-admin   lists.m4if.org]On Behalf Of Rob Koenen
> Sent: Wednesday, January 08, 2024 10:03 AM
> To: cloverleafland   mail.hongkong.com; m4if technotes
> Cc: li zhengming
> Subject: RE: [M4IF Technotes] Re: Compression Ratio
>
>
> There is basically no single answer to this question.
> The compression ratio depends completely on the bitrate
> you choose.
>
> Rob
>
> > -----Original Message-----
> > From: cloverleafland   mail.hongkong.com
> > [mailto:cloverleafland   mail.hongkong.com]
> > Sent: Wednesday, January 08, 2024 3:15 AM
> > To: m4if technotes
> > Cc: li zhengming
> > Subject: [M4IF Technotes] Re: Compression Ratio
> >
> >
> > Dear all,
> >
> > I would like to ask what's the common aprox. compression
> > ratio a MPEG-4 encoder perform?
> >
> > Thanks...
> >
> > Regards,
> > Clover
>
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