[MPlayer-users] mencoder, file sizes

[Felix Buenemann]

On Sunday, 11. November 2001 22:17, you wrote:
> [Automatic answer: RTFM (read DOCS, FAQ), also read DOCS/bugreports.html &
>  http://gcc.gnu.org/gcc-2.96.html if you still have questions or problems]
>
> Hello,
>  Situation is like this - I tried to compress some files from .mpg
> format to divx, using both mencoder and transcode some time ago.
>  Sometimes output is just great - 4x smaller filesize, ideal quality,
> but sometimes it goes very bad - divx4 is almost the same as input, and
> sometimes even up to 20% larger.
>  It seems there is some corelation between source quality and compression
> - when source is very good I get big gains on filesize, when it's ok there
> is no noticable gain, and when source movie quality is poor, then divx4
> gets bigger.
yes, the cleaner the input video the better it can be compressed, compression 
artefacts in input video are unhealthy to encoders.

>
>  Is this supposed to be like this? Or am I doing sth stupid?
> I haven't tried 2pass thing, but i suppose this would change things a lot.
> Maybe I should apply some postprocessing/smoothing to the source movie and
> then try to compress it?
two pass should improve filesize predictability and average quality among the 
movie. And yes postprocessing can help to reduce atefacts in input video so 
it's better compressable (like noise filters, deblocking, deringing,...).

-- 
Best Regards,
	Atmos
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