Transmission of high rate isochronous data in MPEG-2 data streams
First Claim
1. A method for the robust transmission of high rate isochronous data in an MPEG-2 type transport stream, comprising the steps of:
- providing said isochronous data in a packetized elementary stream (PES) having a PES header preceding a PES payload, said PES payload including an isochronous data header followed by a plurality of isochronous data presentation units;
aligning said isochronous data header and the presentation units which follow within said PES such that the first byte of the isochronous data header immediately follows the last byte of the PES header;
inserting a clock increment value in said isochronous data header specifying the ratio of said isochronous data rate to a reference clock rate, said clock increment value enabling said isochronous data rate to be derived from said reference clock rate at a decoder; and
packaging said PES into a plurality of isochronous data transport packets such that a first payload byte of each transport packet is the first byte of an isochronous data presentation unit and a last payload byte of each of said packets is the last byte of an isochronous data presentation unit.
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Abstract
A scheme is provided for communicating high rate isochronous data in an MPEG-2 type transport stream in a robust manner. The syntax for the data bitstream also provides for the communication of a data clock increment value to a decoder. The increment value enables a simplified and cost effective approach to the direct digital synthesis of a clock frequency necessary to recover data from the packetized data stream at the decoder. The time resolution for presenting isochronous data presentation units at the decoder is increased by providing a presentation time stamp (PTS) extension to supplement a standard MPEG-2 PTS.
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Citations
22 Claims
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1. A method for the robust transmission of high rate isochronous data in an MPEG-2 type transport stream, comprising the steps of:
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providing said isochronous data in a packetized elementary stream (PES) having a PES header preceding a PES payload, said PES payload including an isochronous data header followed by a plurality of isochronous data presentation units; aligning said isochronous data header and the presentation units which follow within said PES such that the first byte of the isochronous data header immediately follows the last byte of the PES header; inserting a clock increment value in said isochronous data header specifying the ratio of said isochronous data rate to a reference clock rate, said clock increment value enabling said isochronous data rate to be derived from said reference clock rate at a decoder; and packaging said PES into a plurality of isochronous data transport packets such that a first payload byte of each transport packet is the first byte of an isochronous data presentation unit and a last payload byte of each of said packets is the last byte of an isochronous data presentation unit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. Apparatus for recovering isochronous data carried at an isochronous data rate in an MPEG-2 type transport stream comprising:
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means for locating a packetized elementary stream (PES) header and an isochronous data header in a received isochronous data transport packet stream; means for extracting program clock reference (PCR) values from said isochronous data transport packet stream; means responsive to said PCR values for recovering a reference clock rate; means for extracting a clock increment value from said isochronous data header; means for processing said extracted clock increment value and the recovered reference clock rate to reproduce said isochronous data rate; and means responsive to the isochronous data rate reproduced by said processing means for recovering said isochronous data. - View Dependent Claims (15, 16, 17)
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18. Decoder apparatus for recovering information data from a data stream, said information being transmitted in said data stream at an information data rate, comprising:
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a direct digital synthesis (DDS) clock for providing a plurality of reference clock rates based on a system clock frequency; means for locating an information data header in a received information data transport packet stream; and means for extracting a clock increment value from said information data header, said clock increment value specifying the ratio of said information data rate to said system clock frequency; wherein said DDS clock is responsive to said clock increment value for providing a clock signal at said information data rate for use in outputting said information data. - View Dependent Claims (19, 20, 21, 22)
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Specification