get keyframes from TrackTo

I want to animate an armature using a video tracking.
I have used the track to bone constraint on the bones of my armature, with targets the empties that follow the tracks i got from the video. My problem is this: when i set keyframes i ignores the bone constraint, because it doesn’t change the values for the rotation of the bones that are visualized and highlightened. How can i “convert” the track to to keyframes, or get the rotation it applies?