[MEncoder-users] estimate the final length of a file

Kasper Kristoffersen kdk at bangpro.dk
Thu Feb 23 15:26:58 CET 2006

Sergio wrote:

>Hash: SHA1
>Hi again!
>I need to know the final length of a file after being converted by
>Mencoder. Currently I do it using the formula:
>	(audio_rate+video_rate)*length
>with AUDIO_RATE and VIDEO_RATE expressed as bytes/second and LENGTH as
normally, the bitrates are in (k)bit/sec, not bytes, but I'm guessing 
you have converted to bytes/sec yourself.

>seconds. Unfortunately, the size is overestimated in about a 35% (i.e.
>when the estimation says 4.4 GBytes, the true final size is about 3
>Is there a way of better estimate the final length?
I'm not pro at this, but my guess would be, that some frames aren't 
using full bitrate (like a pure black-frame not using e.g. 4Mbit of data).

Kasper Kristoffersen

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