Camera Background image

HI there,
I’m trying to use a script to set the duration,start, offset of my background image - sequence.
Unfortunately the log in the info-panel doesn’t help.
This is how far I came:

import bpy
scn = bpy.context.scene
scn.frame_start = 1
scn.frame_end = 200

filepath = “D:/_BlenderPrj/20_05_Dino/movies/cars_mod/cars_mod.0001.jpg”

cam = bpy.context.scene.camera

img = bpy.data.images.load(filepath)
cam.data.show_background_images = True
bg = cam.data.background_images.new()
bg.image = img
img.source=‘SEQUENCE’

bg.image.sequence.frame_start =20

Thanks
Andi