Video encoding -> video playing speed problem

[stic at free.fr]

Dear all,

First I hope I am on the right mailing list, please tell me if I'm not on the right place for this.
I need you input to understand the following issue ...
I have a custom src element that provides me video/x-raw-rgb data.
I can encode it to a video file without any problem BUT the more I increase the framerate parameter the more the result video has a high playing speed ... !!
I don't understand why as it doesn't seems to me to be a performance problem.
I'm pretty sure this is a known (maybe nooby) problem, please can someone tell me what to do ?

Thank you all.

Best regards,
Nicolas.