Quantitative determination of plasma parameters based on optical emission measurements usually requires two types of calibration. First, in order to be able to calculate the absolute values of emission intensities, the transmission of the optical system must be measured with the help of a calibrated source or detector. Second, if utilizing the ratio of atomic-to-ionic lines for determining the electron temperature Te, another quantitative method, e.g. Langmuir probes, must be applied for calibration of the absolute value of Te. However, the necessary plasma modeling must take into account the particular geometry of the system, because the Langmuir measurements are local, whilst the sampling of the optical signal involves plasma volume along the line-of-sight. Such modeling can be complex, especially in conditions of high-pressure sputtering of multielemental targets in a mixture of reactive gases. Nevertheless, appropriate data handling of relative optical emission measurements can give information about variations of deposition conditions, which have an impact on the properties of deposited films.This paper presents results of implementation of optical emission spectroscopy as a tool for detecting deviations in sputter deposition conditions, including gas composition, pressure and target cation ratio. Films deposited under varying conditions were subsequently characterized.