Let's say you are receiving photons from all over. The velocity of each photon coming to you is c. If you moved at velocity v compared to your initial inertial frame, without SR you would say that photons going the same direction as you are moving at c-v, while the photons going the opposite direction do so at c+v. How does time dilation bring both values back to c? It makes no sense to me. Length contraction seems to reverse this perception. So how does the speed of light become constant?