Video Transmission, Anti-error Method

This paper reviews the methods and techniques that have been developed for image quality evaluation and error concealment in the past. On the base of these methods, we propose a new image quality evaluation measure that is called GWSB_PSNR, and proposes joint source coding adaptive (ISA) error concealment method.Traditional objective image quality evaluation measures, such as the MSE or the PSNR , only represent the total difference between the original images and reconstructed images. However in some case, such as there are few large error pixels and many small error pixels in an image, they have not a consistent a result with subjective measure. To cope with this drawback, we propose a new image quality evaluation measure that is called geometry weighted separating block peak signal to noise ratio (GWSB_PSNR)- It bases on weighting separating block peak signal to noise ratio. It corresponds to human visual observations very well. The experimental result shows that this method is valid, reliable, wieldy and extensible.It is well-known that conventional error concealment techniques are the remedy when the error is detected at the receiving end, the quality of recovered image cannot be controlled using these method. When there are faster movement, amoeboidmovement, curvature movement and scene changing in video sequence, the quality of recovered image is worse, and the "blocking effect" is more serious. To cope with this drawback, this paper proposes joint source coding adaptive (JSA) error concealment method, which is a preventive method. At the source coding end, the quality of recovered macro-block is judged, if the quality is worse, the macro-block is transmitted twice; if the quality is good, the macro-block is transmitted once; if the quality is better, the macro-block is not transmitted, in such case, the macro-block is substituted by the one using error concealment method. In fact, because the video sequence is correlative strongly in the temporal and spatial field, the amount of the macro-block whose recovered quality is worse is less, however, the amount of the macro-block whose recovered quality is better is more. The method this paper proposed can both decrease transmitted the quantity of data and increase the quality of recovered image. Simulation results show it is quite effective.