In mobile video applications, the error-prone wireless connection can cause the stream to be incorrectly received. An occurring error will propagate both spatially (in the current frame) and temporally (to the following frames). This work presents the implementation of an error detection and concealment mechanism for H.264/AVC encoded video and the design of a quality estimator. The detection is performed by means of two interacting strategies. At bit level, the syntax of the received bitstream will be analyzed in order to detect inconsistent or illegal codewords. At the pixel level, the remaining visual impairments in the decoded frame will be detected. The quality estimator is capable of, given the information output by the decoder, to estimate the subjective quality of the decoded H.264 video. This detection and concealment is implemented in the H.264/AVC decoder, without causing transmission overhead. Simulations show improvements both in objective (luminance peak-signal-to-noise ratio) and subjective (mean opinion score) tests with respect to the common slice rejection mechanism. The quality estimator is only a Matlab design and is not implemented in the decoder.