Abstract:
A method of, and apparatus for, encoding and multiplexing a digital video picture are provided using intra-coded fields only at a relatively high bit-rate, with each picture being encoded as a sequence of slices from the video image field. The encoding suitably complies with MPEG or similar requirements, and the intra-coding is further constrained so that the maximum number of bits for each slice in the picture is limited, and the delivery schedule of the bits to a decoder is more tightly constrained than is implied by the MPEG decoding models. In this way it is possible to build a high quality, low cost MPEG (or similar) encoder and decoder for video communications over digital interconnection standards such as IEEE 1394.
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:
Various methods are disclosed for producing an edited MPEG audio/video stream from first and second streams recorded in a transport-stream format normally intended for broadcast purposes. According to one implementation, a bridge sequence is generated which recodes data from both of the original streams, in the region of the edit point. Padding packets are inserted in the elementary streams to adjust a continuity counter values so as to allow continuous decoding across the join between bridge sequence and second sequence proper. In another implementation, seamless playback is not required, the bridge sequence is omitted, and various process are implemented nullon-the-flynull to generate an edited stream compliant with MPEG-2 specification. To this end, exit and entry points are constrained to certain types of coded pictures, and offset between time-bases is adjusted to avoid buffer overflow.
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). However, based on parameters and constraints imposed upon the input stream by the MPEG or other specifications, a remultiplexer 412 is able to reschedule and repacketise the elementary data streams into a valid output stream (TS), without the size of buffer that would be required for multiplexing of the elementary streams from scratch.