[MEncoder-users] filesize become very big after convertion

Nicolas George nicolas.george at ens.fr
Tue Aug 22 00:48:40 CEST 2006

Le quartidi 4 fructidor, an CCXIV, Corey Hickey a écrit :
> 3. Scale the video down somewhat (-vf scale=xxx:yyy). This will make the 
> video smaller, of course, and lose some detail, but to a certain point 
> this usually looks better than blocky artifacts.

This is not necessarily true. If you scale down the source, you will
certainly get, for the same bitrate, a better quality with regard to the
scaled content, which is what the "psnr" option of mencoder shows. But with
regard to the original content, the quality may be lower.

For example, for DVD-style content, with target bitrate in the 500-1300 kb/s
range, scaling the video down to 720×405 gives worst results than keeping
the original, and scaling down to 640×360 even worst. On the other hand,
scaling up to 1024×576 gives better results.


  Nicolas George
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