Viewing quality assessment is important in every phase of coder development and deployment, and also in the design and operation of video streaming services. In the development and design phases an objective metric is more cost-effective and less time-consuming than a subjective assessment. The behavior of the impairment caused by packet-delay-variation (PDV) over quality inspires the conception of the viewing-quality-objective metric (VQOM), which is proposed here. A single spline function is used as a prototype whose parameters are trained by a deterministically constrained mean square error statistical method. Test results are presented for a sizable database of Absolute Category Rating (ACR) subjective scores corroborating the assumptions in the definition of VQOM.