3D Visual Communications

8.1 Transmission-Induced Error

The transmission of video over a communication channel adds to the challenges associated with source compression, those arising from the errors that inevitably would be introduced in the channel. The presentation in Chapter 6 should have conveyed, among others, the message that while some channels are more benign, introducing errors less frequently than others, all channels do introduced errors. Therefore, when considering the quality of the communicated video from an end-to-end perspective, the experienced distortion will not only be due to the compression operation, but also due to channel errors. To differentiate these two types of distortions, we will be calling the former “source encoding distortion” or “source compression distortion”, and the latter “channel-induced distortion” or “transmission-induced distortion”.

Of course, channel errors will introduce a channel-induced distortion to the end-to-end video quality, but the magnitude of this distortion usually depends on several variables, such as the source encoding method used on the source, the error pattern introduced by the channel, the importance of the affected information from the human perception perspective, and so on. Indeed, practical video encoders frequently need to make use of and combine multiple techniques in order to achieve good compression performance. As a result, the bit stream at the output of a source encoder may be formed by different components, each having been generated ...