A unified wave-phase description of the photon and of the motion of a material body is developed. The construction is based on the description of wave processes and on the preservation of their phase state as a fundamental principle, leading to Lorentz transformations and the structure of Minkowski spacetime without introducing them a priori. It is shown that the physically significant characteristic of a wave process is its phase state, which is preserved during evolution and acquires physical meaning only through the comparison of different processes. The wave invariant associated with the motion of a material body is factorized into two oppositely directed light-like components Q± = Ω ± cK = 2Ω_{l,±}, whose product, after a natural rescaling, takes the normalized form Q₊Q₋ = 1. In this representation, the parameters (Ω, K) are not independent quantities but are determined by the two light-like components: Ω characterizes their combined frequency content, whereas cK characterizes the asymmetry between them. Within the proposed framework, the Doppler shift is interpreted as a phase relation between wave processes, while relative velocity in special relativity corresponds to a Doppler asymmetry between the two light-like components of the wave process associated with motion. The resulting construction reproduces the kinematic structure of special relativity and provides a unified wave-phase description of the photon and of the motion of a material body.