Abstract: Broadcast data received in MPEG Transport Stream format (TS) is processed (8) to produce a modified transport stream for recording on an optical disc (3) to record the content of a selected audio-visual program. Various techniques are disclosed for permitting random access within the recording, but without re-packetising or remultiplexing the audio and video elementary streams, for example into program stream format. The received TS (DVIN) occasionally includes stream mapping information (PAT/PMT) identifying a transport packet ID code associated with each elementary stream, said stream mapping information being subject to change throughout the received TS. The packet IDs in the modified transport stream can be re-mapped to a uniform set of values to permit random entry to the recorded stream. Alternatively, the current stream mapping information may be inserted at every potential entry point in the modified stream.

Abstract: A digital video recorder or similar apparatus implements a method of converting an input data stream having an MPEG-2 Transport Stream (TS) format into an output data stream having an MPEG-2 Program Stream (PS) format. The input data stream (TS) includes data of at least first and second elementary data streams (404, 406) formed and multiplexed in compliance with a TS decoder model. The first elementary stream is a video stream, while the second stream is an audio stream of lower data rate. The input stream is parsed (402) and the elementary streams are demultiplexed into respective FIFO queues 404/406. Each stream is further parsed to obtain and calculate time stamp information which is queued separately at (408/410) with pointers to the stream data (at 404/406). The schedule and packetisation applied to the elementary streams in the input stream (TS) cannot be applied directly in creating the output stream (PS).

Abstract: A digital video recorder or similar apparatus implements a method of converting an input data stream having an MPEG-2 Program Stream (PS) format into an output data stream having an MPEG-2 Transport Stream (TS) format. The input data stream (PS) includes data of at least first and second elementary data streams (404, 406) formed and multiplexed in compliance with a PS decoder model. A scheduler (412) within the apparatus inhibits reading of a further data block from the input stream when, in the absence of a vacancy for data of an audio elementary stream within a target decoder model (418), a clock reference (SCR) of said input data stream advances beyond a clock reference of said output data stream by a predetermined waiting threshold.

Abstract: In an image source for multimedia applications such as networked computer games, a graphics engine (16) generates pixel images one line at a time using a scan-line algorithm and supplies the generated scan lines to an encoder (18) where they are buffered. The encoder codes the buffered pixel data as macroblocks of, for example 16.times.16 pixels according to MPEG or similar standards. When the graphics engine has sent sufficient scan lines for a first macroblock to the encoder, it sends a signal (FLAG) on receipt of which the encoder begins coding the pixel data as a macroblock in a line of macroblocks whilst continuing to receive scan lines from the graphics engine (16). To increase encoder efficiency, the graphics engine specifies to the encoder global (GMV) and macroblock (BMV) motion vectors for substantially all or selected ones of the macroblocks of an image respectively.

Abstract: A method and apparatus for improved motion vector selection in the motion estimator stage of a video encoder such as an MPEG coder are provided. From a received (re-ordered) image frame sequence, a first stage (14) of the estimator generates a set of candidate motion vectors, suitably from a list of half-pixel candidates from about each of N candidate integer pixels. Those candidate vectors, together with an indication of their respective accuracies, are passed to a vector selection stage (16). A vector bit counter (18) determines the number of bits required per vector and the selection stage (16) then selects those of the candidate vectors for a macroblock line (or "slice") which minimise a cumulative cost function for the line and provide the best trade-off between motion vector accuracy and required bit rate for each block of the line. The derivation of the cumulative cost function and its application to coding mode selection is described.

Abstract: In a decoder/display system, a pre-processing stage (10) re-codes intra coded macroblock data in an image to produce an independent representation which observes byte alignment. Macroblock data is stored in structured form (26) so that it may readily be indexed for fast copying into foreign images. To avoid differential coding problems, two separate representations of each macroblock are generated for use as the first in a line of macroblocks or as part of a continuation of a line of macroblocks. The pre-processing stage may be used to combine separately encoded pictures and also to separate sprites (objects having a defined boundary) from their original scene. The content of the pictures may be changed at run-time by choosing combinations of macroblocks in a sequence of images to produce the desired effect.

Abstract: An apparatus for identifying automatically from an interlaced video recording the frames of an original cine-film sequence from which the video recording has been derived. The apparatus includes an evaluation for evaluating, for each successive pair of fields, a function measuring correlation between adjacent odd and even picture lines taken from the first and second fields of the pair, respectively; a comparator for comparing the correlation function of each field pair with that of at least one neighboring pair in the sequence; and a selector for identifying pairs with greater correlation than their neighbors as being derived from the same original film frame. The original frames are reconstructed and fed to an MPEG motion picture encoder to obtain high quality compressed video, Also provided is automatic scene cut detection which allows adaptive operation of the MPEG encoder.

Abstract: In the encoding of a frame (P3) in a digitised motion picture sequence, the frame is divided into blocks (A) of pixels and a motion vector (VA) found to predicts the contents of each block A from a block (A') in a previous frame (I0). Rather than evaluate many thousands of candidate vectors to find the best motion vector (VA), relatively few candidate vectors are evaluated, based on starting vector which is the estimated motion vector for a neighbouring block (LB(A)) in the same frame. To allow parallel processing of several pixel blocks, all the blocks of one row in the current frame are assigned to one processor (DSP), and a starting vector is obtained from a block (LB(A)) previously processed by the same processor. Further starting vectors are obtained if desired from neighbouring blocks (UR(B),DR(B)) in neighbouring frames of the sequence. The candidate vectors based on a starting vector may be very few in number, or may fill an area a few percent of the full search area.

Abstract: A luminance signal (Y) is applied to a segmentation device (2) which subjects the signal to a segmentation algorithm to produce a region image signal which is then encoded in a region image encoder (3). The region image signal is also applied to a region post-processor (4) in which an adapted smooth function is added to the region signal. The resulting modified region image signal is subtracted in subtractor (5) from the luminance signal to produce a texture signal which is encoded by a texture image encoder (6). The encoded signals are conveyed via a data channel (9) to respective region (12) and texture (14) image decoders and the recovered region image signal is post-processed in a processor (13) in the same manner as with processor (4). The resulting modified region image signal and the recovered texture image signal are added in an adder (15) to produce a reconstructed luminance signal.

Abstract: A luminance picture signal is applied to segmentation device (2) and a modal filter (3) to produce a region signal. Both the picture signal and the region signal are applied to a subtractor circuit (5) to produce a texture signal which is encoded in an encoder (7). The region signal is also applied to an edge mapping device (9) to produce a region list signal and an edge map of the original image. The edge map is subjected in an element prediction device (10) to a template to produce a prediction from a look-up table in a memory (12) regarding the value of an element in a fixed position adjacent the template. If the prediction is correct then a prediction error signal indicates no error while if an error exists either the prediction error signal conveys the actual value or where it may be found in a look-up table. The prediction error signal is encoded in a second encoder (14).

Abstract: A method of and apparatus for processing a picture signal for transmission in which the picture signal (Y) is applied to a segmentation device (2) where it is subjected to a segmentation algorithm to identify regions of similar intensity. The resulting region signal is applied to a modal filter (9) in which region edges are straightened and then to an adaptive contour smoothing circuit (10) in which contour sections identified as representing false edges are filtered. The filtered signal is subtracted from the original luminance signal in a subtractor (12) to produce a luminance texture signal which is encoded by a texture encoder (17). The region signal is encoded in a region encoder (24) together with flags indicating which of the contours in the region signal represent false edges.