[FFmpeg-user] MPEG1/2 does not support 3/1 fps

[db123 at bergqvist.se]

I want to stream my web cam /dev/video0 using ffmpeg and ffserver. I 
have compiled the latest sources by looking at this page:
https://trac.ffmpeg.org/wiki/CompilationGuide/Ubuntu

Now I try to start ffserver by looking at this page:
https://trac.ffmpeg.org/wiki/ffserver

I have created /etc/ffserver.conf with this content:
http://ffmpeg.org/sample.html

And I start ffserver with:
ffserver -d -f /etc/ffserver.conf

Then I start ffmpeg with:
ffmpeg -f v4l2 -s 320x240 -r 25 -i /dev/video0 -f alsa -ac 2 -i hw:1,0 
http://localhost:8090/feed1.ffm

But I get the errors:
MPEG1/2 does not support 3/1 fps
Error while opening encoder for output stream #0:1 - maybe incorrect 
parameters such as bit_rate, rate, width or height

My web cam is a "Creative Live! Cam Sync HD" with 1280x720 resolution 
and I have Ubuntu Linux.

Kind regards,
Daniel