Abstract: The coding or decoding of video data with the associated audio and/or other data can be performed, for example, on the basis of the standards ISO/IEC 11172 (MPEG1) or ISO/IEC 13818 (MPEG2). Such coding and decoding can include the conversion of a primary bit stream coded on the basis of such standards into a secondary bit stream with a different data rate. Since the information content of the motion vectors from the primary bit stream retain their validity in the secondary bit stream, it is not necessary to recalculate motion vectors for transcoding. Instead, encoding of the secondary bit stream is performed with the aid of the motion vectors from the primary bit stream which are reused. In such a case, the encoding of the secondary bit stream is carried out in a restricted prediction mode, i.e. only those prediction modes which are described by respective block type or the motion information of the primary bit stream are allowed in the secondary bit stream.

Abstract: In the process of generating a compatible 4:3 letterbox format television signal, a wide aspect ration 16:9 progressive scan television signal is vertically transcoded from 575 to 431 image lines, converted to line interlaced form and horizontally compressed. A vertically transcoded interlaced luminance component is converted back to progressive scan form via interpolation, and subtracted from a vertically transcoded original progressive scan luminance component to produce a difference (helper) signal. The difference signal is time compressed and multiplexed into upper and lower edge bar regions of the letterbox format. The compatible letterbox signal also is encoded with additional information including vertical high frequency information and horizontal high frequency information separated during the transcoding and compression processes, respectively. The encoding includes modulating the color subcarrier frequency with luminance information, and intraframe averaging.

Abstract: Method of correcting television signals transmitted in blocks, including detecting defective blocks with an error detection circuit and calculating substitute information for a block determined to be defective from an environment of the defective block or from a television signal preceding in time the signal containing the defective block.