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List:       kde-multimedia
Subject:    thanks for mpeglib
From:       Joerg Anders <j.anders () informatik ! tu-chemnitz ! de>
Date:       2002-03-13 8:50:50
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Hi!

I'd like to express my admiration to all developers of
the mpeglib. I installed KDE3 and this way for the first time
I saw the new MPEG players on basis of the mpeglib.

I think I know the problems because some time ago I wrote
a MPEG player in Java:

http://rnvs.informatik.tu-chemnitz.de/~jan/MPEG/MPEG_Play.html

which only decoded the MPEG-1-video and skipped the audio tracks.

I tried to port it into C (or C++) to add audio decoding. But
I never achieved sufficient decoding speed. Although I 
implemented some tricks (multiplication tables, shared memory in X,
Huffmann decoding as inline macros, interger arithmetics in IDCT).
Furthermore I used a 2D IDCT algorithm (by Feigg). There are
some tests which proof it speeds up the Berkeley's "mpeg_play":

http://rnvs.informatik.tu-chemnitz.de/~jan/MPEG/HTML/idct_discussion/Index.html

Nothing helped. I used gprof to find out what takes so long.
Very surprising to me: It is not IDCT (or so ...) , it is the YUV --> RGB
conversion. (??) 

Good to know that Linux now has a good and free MPEG video/audio decoder.

-- 
J.Anders, Chemnitz, GERMANY (ja@informatik.tu-chemnitz.de)

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