[FFmpeg-devel] [PATCH] NellyMoser audio decoder

Andrew Savchenko Bircoph
Wed Sep 12 04:36:38 CEST 2007


On Wednesday 12 September 2007 04:57, Michael Niedermayer wrote:
> but i suspect that even 2 mplayer/mencoder with different input
> files would end up with quite a few identical pages which are
> not simple tables or directly part of the object files
> an example would be tables generated depening on user
> parameters, coefficient tables for audio resampling which depend
> on input and output frequencies similarely for video/imag
> rescaling

But just imagine that such kind of page will be changed at runtime, 
e.g. due to current movie aspect ratio chang at runtime by first 
instance of mplayer. There are 2 possibilities: 1) pages should be 
marked somehow as absolutely unchangable by application (and this 
will reduce memory saving greatly) or 2) kernel must perform check 
for no changes (probably rehash) each reused page each time 
accessing it, this may utilize CPU greatly. So statement about 
efficiency of reusing memory pages seems to be rather questionable 
for me.
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