[Ti] Re: MPEG, was "Re: Dual Layer cable for Powerbook G4 400"

Chris Olson chris.olson at astcomm.net
Wed Dec 14 10:32:30 PST 2005


On Dec 14, 2005, at 9:56 AM, Mikael Byström wrote:

> Doesn't the graphic cards of the titaniums do MPEG-2 decoding? At  
> least earlier models of iBooks and the Pismo had this built in by  
> default hardware.

There's no way.  The GPU simply doesn't have enough processing power  
to decode MPEG-2 on the fly.  For instance, a real hardware MPEG-2  
decoder such as that found in my DVR cable set-top box has a  
PowerPC750 (no AltiVec support) processor running at 700 Mhz.  And it  
runs at 90% load decoding a HDTV MPEG-2 stream.

> However, at some list I was reading none of us could determine for  
> sure whether Apples software was actually making use of said  
> builtin decoders. If not, the DVD player apps sure decodes MPEG-2  
> much faster than VLC or MPlayer. I think the latter 2 do it  
> completely in software?

They all do it in software.  The MPEG-2 decoder in MPlayer is a  
reverse engineered decoder - and not licensed.  MPlayer also uses Jon  
Lech Johansen's DeCSS algorithm to decrypt, which is also illegal (at  
least in the US).  Of course, Linux users use this every day, but  
it's still illegal to watch a DVD on a box running linux in the US.   
That's why that software is developed and distributed off US shores,  
and not distributed with "pure" free software like the Debian  
Project.  libavcodec and libmpeg2, the two "free" open source MPEG-2  
decoding libraries are both illegal.  MPEG LA doesn't consider "free"  
software to be much of a commercial threat, so nothing is done about  
it (yet).
-- 
Chris

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