[MPlayer-users] Re: file size falls short of 700MB for multi pass

D Richard Felker III dalias at aerifal.cx
Wed Jul 2 07:14:39 CEST 2003

On Sun, Jun 22, 2003 at 07:22:28PM -0500, Jonathan Rogers wrote:
> [Automatic answer: RTFM (read DOCS, FAQ), also read DOCS/bugreports.html]
> Jason Pepas wrote:
> >I used 3 pass encoding on a file, and specified the suggested bitrate for 
> >a 700MB cd given after the first pass.  However, the final filesize was 
> >only 580MB.
> >
> >what exactly does this mean?  that using more bits in this specific 
> >instance would not improve quality?
> No, it almost certainly doesn't mean that more bits wouldn't improve 
> quality. Libavcodec's rate control is far from perfect. For most movies, 
> it gets pretty close, but on some, it uses way too few bits. So far, the 
> only way I've been able to fix it is to reencode, specifying a higher 
> bitrate.

Most likely it means your input file (dvd?) was "soft telecined", and
you need to specify -ofps 23.976 for the rate control to work right.
This is definitely the case if you see lots of "duplicate frame!" spam
in mencoder output.

Keep in mind that failing to use -ofps will not only mess up rate
control, but also generate horribly ugly choppiness in the output
file, since every 4th frame will be shown for double duration!!


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