Changing Duration of custom playable clip

I'm trying to make one of my custom playables become a specific duration at the beginning of it's life when i'ts added to the timeline. Adding code in Awake to the customPlayableClip class (here Anim_SpineAnimationClip.cs) works nicely -- it get my little "Hi!" whenever I ad a new clip to the timeline.
But I havent figured out how to changed the duration of the clip itself.

simply doing
this.duration = 3f
gives error CS0200: Property or indexer `UnityEngine.Playables.PlayableAsset.duration' cannot be assigned to (it is read-only)

and trying
TimelineClip thisClip = this as TimelineClip;
thisClip.duration = 3f;
gives error: Cannot convert type `ANIM_SpineAnimationClip' to `UnityEngine.Timeline.TimelineClip' via a built-in conversion

Any idea how I can accomplish this?

Code (CSharp):

1.  
2. using System;
3. using UnityEngine;
4. using UnityEngine.Playables;
5. using UnityEngine.Timeline;
6.  
7. [Serializable]
8. public class ANIM_SpineAnimationClip : PlayableAsset, ITimelineClipAsset
9. {
10.     public ANIM_SpineAnimationBehaviour template = new ANIM_SpineAnimationBehaviour ();
11.     // public ExposedReference<GameObject> animTarget;
12.     public ExposedReference<Scr_SpineCtrl> animTarget;
13.  
14.  
15.     public ClipCaps clipCaps
16.     {
17.         get { return ClipCaps.None; }
18.     }
19.  
20.     public override Playable CreatePlayable (PlayableGraph graph, GameObject owner)
21.     {
22.         var playable = ScriptPlayable<ANIM_SpineAnimationBehaviour>.Create (graph, template);
23.         ANIM_SpineAnimationBehaviour clone = playable.GetBehaviour ();
24.         clone.animTarget = animTarget.Resolve (graph.GetResolver ());
25.  
26.         return playable;
27.     }
28.  
29.     void Awake(){
30.         Debug.Log("hi");  
31.         this.duration = 3f;
32.         //TimelineClip thisClip = this as TimelineClip;
33.         //thisClip.duration = 3f;
34.     }
35.  
36. }

 

hmm, I think I understand the basics of overriding as a concept but I can't get figure och how to implement this here--

Code (CSharp):

1. public override double duration = 3;

gives error CS0106: The modifier `override' is not valid for this item

and

Code (CSharp):

1.  
2.     public override double duration {
3.         get {
4.             return base.duration;
5.         }
6.         set {
7.             base.duration = value;
8.         }
9.     }

while acknowledging duration as potentially overridable wont let me actually set anything:

error CS0546: `ANIM_SpineAnimationClip.duration.set': cannot override because `UnityEngine.Playables.PlayableAsset.duration' does not have an overridable set accessor

-- I must be going about this wrong?

 

ahhhh that does it, thank you!!

 

Thanks this is super helpful, although the solution is a bit obscure to know to do that, and it's not obvious from API docs