Scientific-atlanta, Inc.

Si Jun Huang

Christopher H Birch

Joel Warren Schoenblum

Michael L Olson

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

Techniques for determining an output rate for a bit stream, the output rate being determined by applying information read from the bit stream to available bandwidths. A digital flywheel provides continuous feedback from an encoding system to a video compression engine in order to assure that the clock rates between the two remain appropriately synchronized.

Method and apparatus for adaptive bit rate control in an asynchronized encoding system

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

Techniques for determining an output rate for a bit stream, the output rate being determined by applying information read from the bit stream to available bandwidths. The techniques are employed to construct a statistical multiplexer that multiplexes varying bit-rate bit streams onto a satellite up-link. Minimum and maximum output rates for each 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 multiplexer looks at the fullness of the memory buffers and correlates the fullness with the likelihood of a condition in which output will exceed bandwidth. If there is not enough bandwidth to give every bit stream its minimum rate, glue frames may be inserted, or low priority channels dropped.

Method and apparatus for assuring sufficient bandwidth of a statistical multiplexer

Techniques for determining an output rate for a bit stream, the output rate being determined by applying information read from the bit stream to available bandwidths. The techniques are employed to construct a statistical multiplexer that multiplexes varying bit-rate bit streams. Minimum and maximum output rates for each 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 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, glue frames may be inserted, or low priority channels dropped.

Method and apparatus for detecting and preventing bandwidth overflow in a statistical multiplexer

Techniques for determining an output rate for a bit stream, the output rate being determined by applying information read from the bit stream to available bandwidths. The techniques are employed to construct a statistical multiplexer,that multiplexes varying bit-rate bit streams. Minimum and maximum output rates for each 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 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, glue frames may be inserted, or low priority channels dropped.

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Suwanee, GA, United States of America

Si Jun Huang