[MPlayer-users] Audio & video file sizes don't add up to actual file size (mencoder)

[Pit Cuppens]

Dear all,

I tried encoding a movie with mencoder using

mencoder dvd://1 -dvd-device VIDEO_TS/ -o movie.avi -alang en -vf 
crop=720:436:0:70,scale=416:-3 -oac lavc -ovc lavc -lavcopts acodec=ac3:
abitrate=128:vcodec=mpeg4:vbitrate=829:vhq:vqmin=2:v4mv:trell:autoaspect:
vlelim=-4:vcelim=9:lumi_mask=0.05:dark_mask=0.01:vpass=2 -endpos 6060

This works fine, and just before mencoder ends, it outputs
the video and audio bitrate: the audio bit rate is 128kbit
and the video rate around 828kbit -- which is wonderful.

Now my problem is the following. Mencoder also outputs
(right after the above bitrates, in parenthesis) the number
of bytes used for video and audio. Again, these numbers
are exactly what I have expected. However, if I add them
together, I get an (expected) total file size which is
*much* smaller (around 30mb) than the actual size of the
movie (as obtained via 'ls' on Unix). Obviously, mencoder
needs some more space for the AVI-format, header, etc.,
and does *not* take this into account in the bitrates.
Is this correct?

And is it also correct that this additional space is
proportional to the movie size? (Because it seems to
me that 30mb is a little bit too much for file header,
etc.) Is there a way to predict this additional space?

Many thanks for your answers,
Pit

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