Abstract: A method and apparatus are provided for communicating HBI user information in digital television data streams via a generic syntax. The syntax allows the digital transport of virtually any type of user data that may be carried in the HBI or overscan portion of an analog television signal. A pixel generator is used to insert HBI data into a digital video signal using information provided in the user portion of the digital data stream. The syntax provides the pixel generator with the start time of the first symbol, the number of pixels per symbol, the high and low levels to insert, the fraction of the symbol time that is transition time, the number of symbols to insert and the first frame line number on which to insert the data.

Abstract: A digital waveform generator complies with different vertical blanking interval (VBI) standards, and is inserted into VBI portions of a digital component video signal. A buffer receives symbols carrying VBI data for a particular VBI service according to a user data syntax, which identifies a television line into which the VBI data is to be inserted. A symbol processor is responsive to information provided by the syntax. This information indicates the number of pixels represented per symbol, a symbol transition time, and the number of symbols carrying data to be inserted into the VBI portion. The symbol processor provides the VBI data in a format according to the particular VBI service. A timing circuit is responsive to a start time provided by the syntax for inserting the VBI data. A level control circuit adjusts the level of the VBI data prior to insertion into the VBI portion in response amplitude values provided by the syntax.

Abstract: An interface for a communications receiver such as a cable or satellite television receiver allows control between the receiver and an external device. The external device can supplement the services provided by the receiver. The interface includes a bidirectional control port for coupling the external device to the communications receiver. Ports for isochronous data and high speed data are also provided. The external device can simulate commands available via a user interface for the receiver, such as remote control actuations. In this manner, the external device can access information and control the receiver (e.g., to tune to a specific television or data channel) via the bidirectional control port. The interface enables the external device to use the full capabilities of the communication receiver for data acquisition and processing. The acquired and processed data is then delivered to the external device via the interface.

Abstract: A method and apparatus are provided for communicating VBI user information in digital television data streams via a generic syntax. The syntax allows the digital transport of virtually any type of user data that may be carried in the VBI portion of an analog television signal. A pixel generator is used to insert VBI lines into a digital video signal using information provided in the user portion of the digital data stream. The syntax provides the pixel generator with the start time of the first symbol, the number of pixels per symbol, the high and low levels to insert, the fraction of the symbol time that is transition time, the number of symbols to insert and the frame line number on which to insert the data.

Abstract: Error recovery is provided for isochronous data ("isodata") obtained from a data stream. Isodata transport packets are monitored to locate isodata presentation time stamps (PTSs). The presentation of isodata from a buffer is synchronized to a system time clock (STC) using timing information derived from the PTSs. Discontinuity errors between said isodata transport packets are identified and, if a discontinuity of no more than one packet is identified, a write pointer of the buffer is advanced by a suitable number of bits to compensate for the discontinuity, while maintaining the synchronization of the presentation with respect to the STC.

Abstract: Audio data is processed from a packetized data stream carrying digital television information in a succession of fixed length transport packets. Some of the packets contain a presentation time stamp (PTS) indicative of a time for commencing the output of associated audio data. After the audio data stream has been acquired, the detected audio packets are monitored to locate subsequent PTS's for adjusting the timing at which audio data is output, thereby providing proper lip synchronization with associated video. Errors in the audio data are processed in a manner which attempts to maintain synchronization of the audio data stream while masking the errors. In the event that the synchronization condition cannot be maintained, for example in the presence of errors over more than one audio frame, the audio data stream is reacquired while the audio output is concealed.

Abstract: A method and apparatus are provided for communicating VBI user information for digital television. A syntax is provided which allows the transport of closed captions, non-realtime video, sampled video and AMOL. Non-realtime video can be used to transport various types of data, such as a vertical interval test signal (VITS) through the system at full resolution. The provision in the syntax of a count for each type of VBI user information enables the adjustment of a digital television data stream to accommodate variable amounts and types of such information without space being reserved in advance. The provision of a priority number in the syntax enables decoders to discard VBI user information priorities which are not supported by the particular decoder.

Abstract: Variable rate data is reformatted for communication to an external device at a fixed rate. Fixed length packets of the variable rate data are recovered from a multiplex of data packets. A packet start byte is added to the beginning of each of the recovered packets. Fill bits are added to the recovered packets as necessary to maintain the desired fixed output rate if the output rate is greater than an information rate of the variable rate data. The recovered packets with the added packet start byte and fill bits are provided as output to the external device at the fixed rate. The recovered packets with the added packet start byte and fill bits are advantageously encoded using alternate mark inversion (AMI) and binary eight zero substitution (B8ZS). The packet start byte and B8ZS substitution can comprise unique AMI violation sequences.

Abstract: A scheme is provided for communicating high rate isochronous data in an MPEG-2 type transport stream in a robust manner. The syntax for the data bitstream also provides for the communication of a data clock increment value to a decoder. The increment value enables a simplified and cost effective approach to the direct digital synthesis of a clock frequency necessary to recover data from the packetized data stream at the decoder. The time resolution for presenting isochronous data presentation units at the decoder is increased by providing a presentation time stamp (PTS) extension to supplement a standard MPEG-2 PTS.

Abstract: A method and apparatus are provided for communicating VBI user information for digital television. A syntax is provided which allows the transport of closed captions, non-realtime video, sampled video and AMOL. Non-realtime video can be used to transport various types of data, such as a vertical interval test signal (VITS) through the system at full resolution. The provision in the syntax of a count for each type of VBI user information enables the adjustment of a digital television data stream to accommodate variable amounts and types of such information without space being reserved in advance. The provision of a priority number in the syntax enables decoders to discard VBI user information priorities which are not supported by the particular decoder.