Object-based quality of service assessment using semi-fragile tracing watermarking in MPEG-4 video cellular services

Third generation cellular systems (IMT2000/UMTS) are expected to provide a large number of innovative services with negotiated end-to-end quality of service (QoS). An object-based system for quality of service assessment is presented to evaluate blindly the quality of a multimedia communication link by means of an unconventional use of semi-fragile digital watermarking. Specifically, a known watermark is hidden into each single object of a MPEG-4 video using a spread spectrum technique. In this fashion, the object and the embedded watermark follow the same communication link. In fact, the degradations endured by the (known) watermark allows the degradations suffered, at the receiver´s side, by the original (unknown) object to be inferred. The quality of service evaluation is based on the calculation of the mean square error between the estimated and the actual watermarks. Experiments show the effectiveness of the proposed method.