Performance requirements inherent in streaming mpeg2

Michel LESPINASSE walken at
Thu May 24 22:00:23 CEST 2001

On Tue, May 22, 2001 at 08:51:45AM -0600, Chris Worley wrote:
> I'm running on a 200Mhz Pentium (please chuckle).
> The performance bottleneck for viewing mpeg2 in realtime seems to be the 
> decoding (not the network/filesystem, not the display).

This is quite expected on a p200.

> Of all the mpeg2 decoders I've tried (mplayer, mpeg12play, xine,
> etc...)  mpeg2dec and vlc seem to be the best (robustness and
> performance).  mpeg2dec is the only player that will play from
> stdin, but it won't drop frames when it can't keep up with the frame
> rate; it just playsback slowly.  This isn't a display problem, I can
> easily change it to only display 1/n frames, but that doesn't
> increase the performance significantly for either the sdl or x11
> output interface.

mpeg2dec doesnt do frame dropping yet. You might want to hack it up to
only decode 1/n B pictures - in decode.c, when we parse a picture
header and the type is B, set a flag saying if you want to decode the
following picture, and then only call slice_process if the picture
type is not B OR if the flag is set.

Good solutions should be based on feedback from how much time the
decoding actually does, but this is harder to implement.

Michel "Walken" LESPINASSE
Of course I think I'm right. If I thought I was wrong, I'd change my mind.

More information about the vlc-devel mailing list