UKHeliBob:
Adding a delay after tilting the quad and then restoring equal power to both sides of the quad will not put it back level. At best it will continue at the same angle in the same direction. It will, however, start falling as the lift produced by the propellers is no longer vertical so you have to increase the power to the motors to compensate.Without a gyro on board all control must come from the pilot and feedback is visual. This is excellent when flying aerobatics but rubbish if you want a stable camera platform. The commercial flight controllers have gyros and accelerometers on board to provide stability when needed
I am not going to put a camera. I just want it to be controlled by my phone I just want it to do basic stuff like fly up down left and right that's all. Once I build this I can always add a gyro and other techs to improve the drone.