The influence of residual errors on a digital satellite TV decoder

摘要

In spite of the use of convolutional and Reed-Solomon codes in satellite broadcasting to protect the MPEG-2 bitstream, residual errors will be found at the input of audio and video decoders. Concealment methods must be elaborated to preserve image quality. In this paper, we simulate the complete transmission system in order to design residual error models. Then, using these models, errors are injected in audio and video bitstreams and their influence on quality is determined with subjective tests. We show that the audio decoding process is much more robust than the video one. So we focus our attention on video and elaborate two concealment strategies. In the first one, the decoder uses the information provided by the system layer to conceal false packets. In the second, a smart decoder is designed which uses bitstream properties to detect and conceal residual errors. We note that the smart decoder gives better image quality than that of the first decoder. Finally, the benefits of concealment strategy are evaluated in terms of CN.