Abstract: Mobile phones now transmit video signals at relatively slow bit rates. The signals transmitted are compressed using inter-frame prediction where sufficient similarity exists between successive picture frames. The receiver includes a decoder which reconstitutes the compressed signals received using signals stored on a buffer representing a previous picture frame. A mode decision circuit compares the signal at the output of the decoder with the previous signal stored and using the same decision criterion as used for the original compression generates a signal which indicates that either the signal is suitable for inter-frame prediction or not. This signal is then compared with the signal from the encoder indicating whether or not the current signal was inter-frame predicted or not. If equality is not detected, then an error may have taken place. Then, error concealment techniques are used.

Abstract: Existing video data compression algorithms exploit the fact that the DCT coefficients in the neighbouring blocks are sometimes similar to those in the current block. This means that if the blocks contain completely different coefficients, for coding video data is disclosed in which element in a prediction matrix is set to an initial prediction value. In the prediction matrix, a smoothing transform is applied to the values along the rows and then along the columns, or vice versa, to obtain interpolated values. The prediction value is reset to the interpolated value and the difference between the reset prediction values and corresponding received pixel values is calculated to produce a residual prediction matrix containing the prediction residuals. A discrete cosine transform is performed on the prediction residuals to obtain elements of a compressed video data matrix.

Abstract: In a GPRS or EDGE or UMTS system, a real-time video service is provided by selecting one of a small number, e.g. four, predetermined channel coding rates applicable for video, applying the rate to the video data in the application layer, and transmitting the data over the radio interface to a mobile system together with, for each burst, a header indicating the selected coding rate and a temporary flow indicator. The short header allows video payload capacity to be increased. One of the predetermined channel coding rates is a {fraction (1/1)} or transparent rate.