Scientific-atlanta, Inc.

Christopher H Birch

Si Jun Huang

Paul D Nicholas

Steven S Lawrence

Christian V Van Staden

Walter R Brooks

Joel Warren Schoenblum

Ajith N Nair

Guy A Primiano

Techniques for determining an output rate for a bit stream, the output rate being determined by applying information read from the bit stream to a model of a receiver for the bit stream. The techniques are employed to construct a statistical multiplexer that multiplexes varying bit-rate MPEG-2 bit streams onto a satellite up-link. Minimum and maximum output rates for each MPEG-2 bit stream are determined such that neither a queue for the bit stream in the multiplexer nor the bit stream's decoder will underflow or overflow. The rates with regard to the decoder are determined using timing information read from the bit stream and a general model of an MPEG-2 decoder. The multiplexer first allocates each bit stream its minimum bandwidth and then allocates any remaining bandwidth to the bit streams in proportion to the difference between the minimum and maximum output rates for the bit streams, with no bit stream receiving more than its maximum output rate. If there is not enough bandwidth to give every bit stream its minimum rate, bit rates are allocated according to priorities assigned to the bit streams.

Using a receiver model to multiplex variable-rate bit streams having timing constraints

Variable rate multiplexer devices have, by definition, a variable output rate for bits of information encoded therein. As a result necessary time sync information such as program clock reference information cannot be guaranteed to be delivered within the time interval thresholds mandated by certain industry broadcast standards, such as MPEG-2 and digital video broadcast (&ldquo;DVB&rdquo;). Transmission of reference signals, such as PCR information, may be assured by inserting detection means to detect the time interval between occurrences of the reference signal. If the interval between occurrences of the reference signal exceeds a predetermined time interval threshold, the detection means will instruct a memory device to provide a reference signal, which is then imprinted with reference signal information and inserted into the stream of information being output by the multiplexer. Alternatively, the multiplexer may simply provide an output signal at a preset predetermined time intervals, regardless of whether or not a reference signal is being provided by the input stream. In this embodiment, the output signal may occur substantially more frequently than is required by the time interval threshold of the relevant broadcast standard.

Method and apparatus for delivering reference signal information within a specified time interval

Apparatus for using a receiver model to multiplex variable-rate bit streams having timing constraints

Method and apparatus for using a receiver model to multiplex variable-rate bit streams having timing constraints

Using a receiver model to multiplex variable-rate bit streams having

A flexible architecture for a digital data receiver including a demultiplexer is provided which allows modular addition of data processors with low complexity and minimal memory requirements. The demultiplexer operates on a scalable frame-based multiplex signal, and interprets the multiplex control data at the start of the frame. With the information interpreted from the control data, the demultiplexer separates individual data services and optionally decrypts them. Data, a data clock and an error flag signal are presented to the demultiplexer input. According to a service requested by a user, the demultiplexer outputs decrypted data clock, error flag and service enable signals in a flow-through manner to an appropriate data processor without data storage.

Multi-service data receiver architecture

A multiplex frame format for transmitting digital data in a data transmission system comprises a PACKETS portion comprising a highly error-protected region and a region having only Reed Solomon encoding as an error protection measure, the PACKETS portion including low speed data. The frame format also comprises portions for transmitting medium (AUDIO) and high speed (VIDEO) data streams following the PACKETS portion. Prior to transmission, the composed frame comprising the PACKETS, AUDIO and VIDEO portions is interleaved and the BLOCK SYNC and FRAME SYNC are added. A multiplex structure control packet word of the PACKETS portion immediately follows FRAME SYNC. Thus, the FRAME SYNC word defines where interleaving begins. A demultiplexer in concert with a microcontroller of a decoder decodes the multiplex structure control word and related PACKETS and outputs digital data streams to related output peripheral processors. The BLOCK SYNC word preferably comprises one eight bit byte and contains network signaling or other data at predetermined bit positions within the word. Moreover, the frame format is flexible and may vary in horizontal and vertical dimensions as digital service streams are varied due to service requirements or priorities. The multiplexers for forming the frame according to the present invention may be arranged in redundant (hot standby) or in multi-service arrangements synchronized by a synchronizing waveform, digitally generated to comprise a continuous 3.375 MHz portion and a single cycle frame marking signal of greater magnitude but significantly lower frequency.

System and method for transmitting a plurality of digital services

Synchronizing waveform generator

A video system for processing compressed video data into composite video data, the composite video data corresponding to a standard composite video signal type selected from a plurality of standard types, the plurality of standard types including at least one of an NTSC composite video signal type and a video signal type, includes a processor, a standard video decompressor and a video interface. The standard video decompressor processes the compressed video data into decompressed video data and user data, the user data having VBI data encoded therein. The processor culls the VBI data from the user data. The video interface processes the decompressed video data and the VBI data into the composite video data with the VBI data encoded therein. The video interface includes a VBI data generator to process the VBI data into VBI signal data, a mixer coupled to the video decompressor to receive the decompressed video data, the mixer being coupled to the VBI data generator to receive the VBI signal data the mixer providing output Y, U and V data during an active portion of a scan line, and circuitry to process the Y, U and V data into the composite video data.

Scan conversion apparatus for improving the vertical resolution of a television image for display comprises a field store for storing the previously transmitted field and a line store for storing video data representative of the previous line including the most recent picture element. In an interlaced system, the two vertically adjacent picture elements and the intermediate picture element transmitted in the previous field are used to provide five selectable values. The video data is also tested in accordance with three tests comprising a rank ordering test, a vertically sharp transition test and a motion test. According to the results of these tests, one of the five alternative values is chosen as an interpolated value for display with the vertically adjacent values for the currently transmitted field. The selection process may be assisted by the provision of an auxiliary signal indicative of the probability of motion of a predetermined block of data.

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Toronto, Canada

Christopher H Birch