How to control the video's viewport in code?

[JamesXu20150314]

Hello,

I want to control the video's viewport in code, but I don't know how to modified the code, Should I modify the following code:

var update = quat.fromValues(controls.manualRotateRate[0] * interval, controls.manualRotateRate[1] * interval, controls.manualRotateRate[2] * interval, 1.0); quat.normalize(update, update); quat.multiply(manualRotation, manualRotation, update);

Also, what's the four number's means in manualRotation?

Who could help me. Thank you very much.

Yours Sincerely, James Xu