[vlc-devel] Re: Question about HD play

Sigmund Augdal sigmunau at stud.ntnu.no
Thu Feb 5 19:45:44 CET 2004

> >What system resources? CPU? memory? io? My laptop has a P4M cpu at 2ghz,
> and
> >it is far from able to decode such a stream. But my 1.8ghz athlon XP can
> >decode it fine. I talked with the libmpeg2 author and he thought perhaps it
> >has something todo with L1 cache. Do the XEON have more L1 cache than a
> P4M?
> I meant CPU as system resource. During stream is displaying, cpu usage rate
> was over 50%.
> My XEON has 12KB L1 cache. (maybe intel P4M has 8KB)
This is about the expected cpu usage on such a system. It takes some cpu to
decode such a high resolution stream. I don't think other players manage to
do this considerably faster than VLC.

> But some problems still remains a mystery.
> For reference, I linked two pictures captured.
> These pictures captured during displaying HD(1080i) source with VLC.
> As shown in pictures, their quality is not good. There are many broken
> pixels.
> I guess the rectangles are macro blocks and  UV processing has some
> problems.
> On low display resolution ( not media resolution ), decoding, displaying
> were done well.
> But on high display resolutions (eg. 2560 * 1024, 2304 * 864 .. etc),
> quality is poor as pictures linked.
> Even decoding work was unstable.
What is the title of video window when the quality is like this? Also, is it
different in the small resolutions when quality is good? Try disabling video
overlay in the preferences, does this affect this problem? (It sure will
give a nasty impact on performance).


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