Abstract: Authorization information, such as blackout and spotlight regions, circular blackout and spotlight regions, and tier pointers, may be transmitted from an encoder to a decoder in a plurality of sessions of data frames. By spreading the authorization information over a plurality of sessions, more space may be allocated for the provision of services. In addition, the authorization information may be framed by START and STOP fields so that the length of authorization information may be variable. Calculation of a circular blackout/spotlight region can be simplified by transmitting a distortion factor from the encoder to the decoder. Accordingly, complex calculations need not be performed at a microprocessor in the decoder.

Abstract: A decoder in a multiservice communication system receives a plurality of services as data streams, including video, audio, teletext, and utility data, multiplexed in sequence of frames. Each service defines a virtual channel. Virtual channel packets contained in the multiplex include information for locating the data streams that compose the virtual channels and information for decrypting the data streams. Each virtual channel packet is transmitted in the multiplex each session of frames. When a user selects more than one virtual channel at a given time, the decoder extracts a virtual channel packet for a first selected virtual channel in a first session. The decoder can then provide the decrypted data streams for the first selected virtual channel to peripheral equipment. The decoder stores the information for locating and decrypting such data streams.