Abstract: A method for seamlessly splicing a local commercial segment into an existing network time slot, without decoder buffer overflow or underflow. The vbv_delay of the commercial segment is manipulated (e.g., for a minimum delay or a maximum delay). The pictures from the commercial segment are output for at least a portion of the associated network time slot duration. A determination is made regarding the number of pictures remaining in a stored portion of the incoming network feed or the commercial segment and the output rate is adjusted as required. The vbv_delay of the stored network feed or the vbv_delay of the local commercial segment is adjusted to match the vbv_delay of the incoming network feed.

Abstract: A system and method for generating a transport packet stream having an output formatted as an ASI group having a plurality of short and long ASI packets in a fixed sequence. The short and long ASI packet each have an associated transport packet and a fixed number of special idle characters and the transport packets are dispersed among the special idle characters.

Abstract: A system and method for generating a transport packet stream having an output formatted as an ASI group having a plurality of short and long ASI packets in a fixed sequence. The short and long ASI packet each have an associated transport packet and a fixed number of special idle characters and the transport packets are dispersed among the special idle characters.

Abstract: A method for seamlessly splicing a local commercial segment into an existing network time slot, without decoder buffer overflow or underflow. The vbv_delay of the commercial segment is manipulated (e.g., for a minimum delay or a maximum delay). The pictures from the commercial segment are output for at least a portion of the associated network time slot duration. A determination is made regarding the number of pictures remaining in a stored portion of the incoming network feed or the commercial segment and the output rate is adjusted as required. The vbv_delay of the stored network feed or the vbv_delay of the local commercial segment is adjusted to match the vbv_delay of the incoming network feed.

Abstract: A transport stream encoder is disclosed which comprises a plurality of FIFO buffers coupled to sources of component signals. Each of the FIFO buffers has a data output terminal for producing component signal data. A packetizer has a data input terminal for receiving component signal data, and produces a packet stream. A data bus is coupled in common to the data output terminals of the FIFO buffers and the data input terminal of the packetizer.

Abstract: A method and apparatus are disclosed for operating a transport stream encoder to produce a stream of packets carrying data representing a plurality of component signals which comprises the following steps. The packet stream is partitioned into successive groups, each group containing a predetermined number of packet slots. A plurality of priority lists is maintained, one for each of the packet slots in the group. Each priority list contains a plurality of entries, and each entry identifies one of the component signals. When a packet slot is to be produced, the entries in the priority list corresponding to that packet slot are traversed, one at a time. For each of those entries it is determined whether the component signal identified by that entry can produce a packet. If it can, a packet containing data representing that component signal is produced. Only if none of the component signals identified by the entries in the priority list can produce a packet is a null packet produced.

Abstract: A video signal encoding system includes a signal processor for segmenting encoded video data into transport blocks having a header section and a packed data section. The system also includes reset control apparatus for releasing resets of system components, after a global system reset, in a prescribed non-simultaneous phased sequence to enable signal processing to commence in the prescribed sequence. The phased reset release sequence begins when valid data is sensed as transiting the data lines.

Abstract: A high definition video system processes a bitstream including high and low priority variable length coded Data words. The coded Data is separated into packed High Priority Data and packed Low Priority Data by means of respective data packing units. The coded Data is continuously applied to both packing units. High Priority and Low Priority Length words indicating the bit lengths of high priority and low priority components of the coded Data are applied to the high and low priority data packers, respectively. The Low Priority Length word is zeroed when High Priority Data is to be packed for transport via a first output path, and the High Priority Length word is zeroed when Low Priority Data is to be packed for transport via a second output path.

Abstract: A vide signal encoding system includes apparatus for segmenting encoded video data into transport blocks for signal transmission. The transport block format enhances signal recovery at the receiver by virtue of providing header data from which a receiver can determine re-entry points into the data stream on the occurrence of a loss or corruption of transmitted data. The number of re-entry points are maximized by providing secondary transport headers embedded within encoded video data in respective transport blocks.

Abstract: Apparatus for decoding an HDTV signal conveyed as high and low priority data in high and low priority channels respectively, wherein said high and low priority data originated from blocks of hierarchically encoded compressed video data, with data of greater importance for image reproduction from each block allocated to the high priority channel and the remaining data from each block allocated to the low priority channel, includes circuitry for identifying and segmenting high and low priority data for corresponding blocks and recombining the high and low priority data into an hierarchically encoded compressed video data stream.

Abstract: Apparatus for encoding/decoding a HDTV signal for e.g. terrestrial transmission includes a priority selection processor for parsing compressed video codewords between high and low priority channels for transmission. A compression circuit responsive to high definition video source signals provides hierarchically layered codewords CW representing compressed video data and associated codewords T. defining the types of data represented by the codewords CW. The priority selection processor, responsive to the codewords CW and T, counts the number of bits in predetermined blocks of data and determines the number of bits in each block to be allocated to the respective channels. Thereafter the processor parses the codewords CW into high and low priority codeword sequences wherein the high and low priority codeword sequences correspond to compressed video data of relatively greater and lesser importance to image reproduction respectively.

Abstract: A plurality of raster-scanned image variables are time-compressed and time-division multiplexed on a line-sequential basis for pyramid analysis. The resulting differential pulse code modulation is statistically encoded and assembled together with digital audio code and synchronizing code. The assembler supplies a serial stream of bits to a transmitter. Receiving apparatus for a video teleconferencing station includes a receiver complementary to the transmitter and a parser for separating digital codewords. Those codewords that are statistical codes descriptive of differential pulse code modulation of video are demodulated. The demodulation results are formatted for a pyramid synthesizer. The stream of samples provided as output signal from the pyramid synthesizer is time-division demultiplexed and time expanded to recover the plurality of raster-scanned image variables.

Abstract: Difference signals are coarsely quantized in a plurality of modes in a DPCM TV system. The fill and rate of fill of the transmitting rate buffer is monitored to prevent errors due to underflow and overflow of the transmitting rate buffer. The data rate is adaptively reduced in response to the rate of fill and fill by an adaptive coarse quantizer which is switched to a more coarse quantizing mode to reduce the transmit data rate. The coarse quantizing values are selected from among the members of the ensemble of values used for the least coarse quantizing mode. This avoids quantizer mode information having to be transmitted to the receiver and giving rise to additional transmitting overhead.

Abstract: In a DPCM video digital data communication system each scan line of a video frame is refreshed with PCM data over a refresh cycle comprising a plurality of frames. Refresh generators at the transmitter and at the receiver are synchronized with an initialization signal and then run asynchronously to select scan lines for refresh. The refresh generators each employ counters for counting a selected number M, which has no factors in common with the number of scan lines of a frame, to select scan lines for refresh which have respectively different spatial positions in adjacent frames to avoid generating visible refresh artifacts. The number of frames in a refresh cycle is adaptively changed to stabilize the fill of the transmitter rate buffer.

Abstract: In a DPCM video digital data communication system, each scan line of a video frame is refreshed with PCM data over a refresh cycle comprising a plurality of frames. Refresh generators at the transmitter and at the receiver are synchronized with an initialization signal and with subsequent refresh cycle synchronizing signals. Also the scan lines and frames are synchronized with corresponding transmitted marker synchronizing signals. The refresh generators run asynchronously between marker synchronizing signals to select scan lines for refresh. The refresh generators each employ counters for counting a selected number M which is an integer having no factors in common with the number of scan lines of a frame to select scan lines for refresh which have different spatial positions in adjacent successive frames to avoid generating visible refresh artifacts.

Abstract: At a sending station in a digital television transmission system embodying the invention, time-division multiplexing either of the spatial-frequency analyses of the video signals from a television camera or of their interframe DPCM responses, both of which have uniform coding rates, is completed prior to symbol coding of interframe DPCM samples. This obviates the problems of time-division multiplexing symbol codes of variable length and of irregular coding rate. Time-division multiplexing is done so as to facilitate symbol coding protocols which include run-length encoding of DPCM samples. At a receiving station in the digital television transmission system time-division demultiplexing takes place after symbol decoding, being done on a per scan line basis.

Abstract: In field/frame recursive filters for providing noise reduction to composite video signal, inversion of the chrominance component of the composite video signal is obviated by selecting nearest neighbor in-phase field/frame delayed signals for recursion. The system arbitrates between two or more nearest neighbor in-phase signals or combinations thereof and feeds back the signal having an amplitude most closely matching the incoming composite video signal.

Abstract: In a differential pulse code modulator for image-representative signals, a coder codes difference signals to produce coded signals which have a highly variable rate, which depends upon motion in the image being represented. A rate buffer receives the coded signals and generates a control signal representative, at least in part, of the rate of fill of the rate buffer. Various filters, decimators and/or coarse quantizers associated with the modulator have characteristics controlled by the control signal in order to tend to control the rate of fill of the rate buffer. This aids in preventing loss of information at the receiver.

Abstract: A predictive coding signal communication arrangement includes, at the transmitter, a subtractor for subtracting delayed predicted signals from current input signals to produce difference signals. Predicted signals are generated by adding the difference signals to the delayed predicted signals, and delay of the predicted signals produces the delayed predicted signals. The difference signals are also applied to a coder for Huffman coding, run-length coding, or the like, and then to a rate buffer for reducing data rate variability. In order to prevent overflow of the rate buffer, a control signal is generated which represents the level to which the rate buffer is filled. The control signal is used to control the data rate reduction or decimation of the current input signals. The decimation of the current input signal produces a data rate disparity, which is corrected by a similar decimation of the delayed predicted signal, and an inverse interpolation or data rate increase of the current predicted signal.

Abstract: A predictive coding signal communication arrangement includes at the transmitter a subtractor for subtracting a delayed predicted signal from current signal to produce difference signals. To reduce the data throughput, the difference signals are data reduced or decimated to produce rate-reduced difference signals. The rate-reduced signals are applied to a coder for Huffman coding, run-length coding or the like, and then to a rate buffer for reducing data rate variability. The rate-reduced difference signals are also interpolated back to the original data rate and applied to an adder together with the delayed predicted signal to produce current predicted signal. The current predicted signal is at least delayed to produce the delayed predicted signal. In a particularly advantageous embodiment, the rate buffer is coupled to a fill control circuit which produces a control signal representing the rate buffer fullness.