Abstract: A method of decoding a bit stream having an embedded clock, where the clock reference data is recovered from the bit stream. The clock reference data is used to create an adjusting value to control a local clock frequency. The adjustment is calculated such that the local clock frequency and the local clock value match the frequency and values in the clock reference data. The adjustment value is input to pulse generator to form a pulse train, which is used to generate the input to an adjustable oscillator.

Abstract: A method of decoding a bitstream having an embedded clock, where the clock reference data is recovered from the bit stream. The clock reference data is combined, typically subtracted, from the system time clock to generate a result. This result is input to a pulse width modulator to form a pulse train, which is used to generate an input to a timing device.

Abstract: A device and method are provided for merging one or more secondary audio channels, received from either a streaming application or from memory, with a primary stream of audio data output from a main audio decoder. In addition to the audio decoder, the device/method employs a controller for processing received secondary audio data in a streaming application, and retrieving from system memory audio PCM data once stored. An audio playback device is provided for formatting the PCM data for mixing with the primary stream of audio data output from the audio decoder. Multiple digital-to-analog converters convert the multiple streams of audio data into analog signals which are then mixed into a single merged audio signal for presentation.

Abstract: A transport demultiplexor for demultiplexing an MPEG-2 compliant transport stream into a system data stream, a video data stream, and an audio data stream. The demultiplexor has frontend logic, a packet buffer, and data, video, and audio unloaders. The front end logic receives transport stream input packets, and delivers the transport stream packets to the packet buffer. The packet buffer, in turn, delivers system data to the system data unloader, video data to the video unloader, and audio data to the audio unloader.

Abstract: A method of storing, in memory, table data. The table data has a packet ID (PID), a Table ID, and a Current/Next Indicator, a section number, and a version number. The first step in the method is specifying the PID ID, the Table ID, and the Current/Next Indicator. The next step is initializing the section number in a table section header to filter to ‘0’. Then, each table section is checked as received to determine if the table section is the last table section for the table. This is indicated in the table section header. If this is the last table section of the table the version number field is incremented, and the section number field is set to ‘0’. If, however, the section is not the last section, the section number is incremented, the next section of the table is incremented, and the next section of the table is stored in memory.

Abstract: A method of generating a pulse input to a voltage controlled oscillator of a digital decoder. The decoder has a system time clock (STC) counter and a Pulse Control Register. The method of generating the pulse input starts from the output of the STC counter and the output of the Pulse Control Register. These two outputs are logically combined and latched.

Abstract: A method of decoding a multiplexed, system layer bitstream. The bitstream is made up of packets of audio, video, and system data. Each packet has a packet header, and data packets. The first step in the process is demultiplexing the bitstream into separate audio and video bitstreams for decompression while maintaining synchronization of the video and audio. The system data and the audio and video packets are next loaded into buffers, from which they are unloaded for subsequent decoding. The decoding is in accordance with the system data entries. The method is characterized by storing the system data and the audio and video packets in a single buffer.

Abstract: A method of implementing a time base change to a time-division multiplexec bitstream, for example an MPEG-2-compatible bitstream. The time base change is in response to a Time Base Change Flag. The bitstreams have video and audio packetized elementary streams, and each of these streams has a common time base. Each of the packetized elementary streams has a packet header, and packet data. The packet headers of the packetized elementary streams each contain a Presentation Time Stamp/Decoding Time Stamp flag field, a Presentation Time Stamp field, and a Decoding Time Stamp field. A time base change is indicated by a change in the PCR. The first step in changing the Time Base is receiving a discontinuity in the bitstream. This is used to disable synchronization of the video and audio bitstreams, and to mark a data byte in the bitstream associated with the Time Base Change Flag. The time base change is carried out and an interrupt is issued when the marked data byte arrives for decoding.

Abstract: An assist processor operates in conjunction with a data path of individual hardware functional units to decode an MPEG-2 compliant data stream. The assist processor has the capacity to assist in processing specific blocks of data, assist in processing every block of data, or assist in processing only blocks of data with an indicator or flag or specific bit or byte set. The assist processor, when notified, modifies the operation of the functional unit or the data that it is operating on, and if necessary, returns the data to the datapath of the hardware functional units. The hardware functional units may operate as an MPEG-2 transport demultiplexor.

Abstract: A method of changing the channels in a digital video and audio receiving system. The method includes receiving and decoding the encoded digital video and audio in a decoder, where the input is a multi-channel, time division multiplexed digital video and digital audio datastream. The datastream contains many Programs, each of the Programs includes a video packetized elementary stream, and an audio packetized elementary stream, each of which, in turn, contains a packet header, and packet data. The channel change method is a process of changing input channels from an old channel datastream to a new channel datastream with a minimum of latency. The method includes setting appropriate flags to request the channel change, acknowledging the requests, flushing buffers, muting audio output and/or freezing video output, and activating a data request line for new channel bitstream data.

Abstract: Method and apparatus for processing a datastream. The datastream contains systems data, which is in tables, other systems data, and payload data. The systems data is used, for example, to control the recovery of programs. The method includes parsing the tables to recover systems data to process the other transport layer data. The method further includes detecting errors in the transmission of table sections and error containing table sections and effectively not delivering the errored table sections to memory.

Abstract: Method and apparatus for processing a data stream. Errors are concealed in the data stream by detecting loss or interruption of data delivery and signalling decoders to invoke error concealment.