Frames come in bursty when capturing with low framerate

Hi List,

I'm trying to capture video at a framerate lower then 25 fps, but something
seems to be wrong with the way I'm doing this.

I'm using the streaming I/O (Memory Mapping) method to capture frames with
the bttv2 driver. I'm queing buffers at a framerate of 10 frames per
second (realtime thread, SCHED_FIFO) with the VIDIOC_QBUF ioctl. I expect
the frames to be captured evenly distributed over time, but it seems that
this is not the case. When I look at the timestamps of the captured frames,
they are 'clustered' or 'bursty'.

With a little picture : (X marks the frame)

This is what I want :
	
    X    X    X    X    X    X    X    X     ----> time

But  this is what I get

    X X       X X       X X       X X        ----> time


(I hope the idea is clear)

The video is now shocky; motion comes shocky and in bursts.

Is this the proper way of grabbig with reduced framerate ? And if so, is
there anything special I should do to get the frames more evenly distributed
through time ?

Regards,

/Ico


-- 
:wq 
^X^Cy^K^X^C^C^C