controlling speed of an action by driver or scripting

I'm scripting some crowd animation. I was searching about a way to control action speed by a driver or keys.
Is there is some attribute for action speed that can be controlled? Something I can access through Python?

I found some related scripts in the game engine which is not what I needed.

The NLA editor.

Action Strip Scale.

Halving or Doubling, (for instance), the strip scale, doubles or halves the action speed.

Animated Strip Time.

The frame at which the fcurve is evaluated can be animated here, with keyframes, AFAIK not with drivers.

Some examples from python console on how to access with script

>>> strip = C.object.animation_data.nla_tracks['NlaTrack'].strips['CubeAction']
>>> strip.use_animated_time
True
>>> strip.strip_time = 100
>>> strip.keyframe_insert('strip_time', frame=200)
True

• thanx batfinger this might work , i'm testing around it might be what i need exactly. – doctor3d Sep 15 '15 at 20:03

Consider an [action constraint]. The transform property of the [target] can be keyframed.

• Please add more to this. As it is it is not an answer. – David Sep 15 '15 at 2:24
• thanx gr8 idea realy, this might work i'll give it a try. – doctor3d Sep 15 '15 at 19:00