🚀 go-pugleaf

In article <8LE5E6I@zelator.in-berlin.de>, leo@zelator.in-berlin.de (Stefan Hartmann) writes:
|> In <l6ulkqINNjbu@calvin.usc.edu> alves@calvin.usc.edu (William Alves) writes:
|> 
|> >Does anyone with experience in MPEG have a feeling for how long it takes
|> >to encode full-motion, full-screen video, with enough compression to
|> >play off a CD-ROM (c. 150k/sec)? I have heard that it would take even
|>      [...]
|> 
|> Hi ,
|> I'm using the Xing Technology MPEG encoder, which works from 320x240
|> TGA frames .
|> It takes 1.5 second per frame to encode to a MPEG-file on a 
|> 486 PC (33Mhz) !
|> I think this is quite fast and all is done by software only !
|> 
|> Best regards Stefan Hartmann.
|> email to: leo@zelator.in-berlin.de
|> 
|> 

This just seems too incredible to me. I can not possibly see how anybody 
can DCT transform a 320x240 frame at that speed on a 486. 

Furthermore I can't see how you could do the motion compensation for an entire frame 
at that speed. The Motion compensation requires an extensive search around each 8x8
pixel block in the image, which amounts to millions of searches just for a single frame.

Another problem which has me confused is that MPEG is not defined for Colourmap
based images which the Xing encoder must use. (you can't do decent real-time colour
quantisation at run time, the images must be pre-quantised, However DCTs do not work
very well with colourmapped images)

I find it hard to believe that the Xing encoder is really MPEG as per the standard.

Ruben.