how about show moving image on screen?

[蒋杰 <cocoinfo sina com>]

Hi,all
        Now I need to show on screen moving image at speed of 25fps(frame per second) which is read from a 
video grab device .
        Every 40ms, I use gnome_pixmap_load_rgb_d_at_size() to load the rgb buffer ,which is converted from 
the YUV buffer from the device,and to show the rgb image  with gtk_widget_show(pixmap).
But,the  image shown on screen flicker !! 
why? to avoid the flicker,should I not use gnome_pixmap,should I use gdk_pixbuf?
and is there a good solution to this problem？
Thanks for your help!
　　　　　　　　　　　　　　cocoinfo sina com