EP0753954A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Transmission of high rate isochronous data in MPEG-2 data streams
Assignee: Arris Technology Inc
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Filing: 1996-07-05
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Granted: —
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Expires: 2016-07-05
Abstract
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.
Inventors
- 👤 Ray Nuber
- 👤 Paul Moroney
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-24 21:34
CPC Classifications
H; H04; H04N; H04N21/00; H04N21/20; H04N21/23; H04N21/236; H04N7/00; H04N7/24; H04N7/52; H04N21/40; H04N21/43; H04N21/4302; H04N21/4307; H04N21/43072; H04L; H04L65/00; H04L65/60; H04L65/70; H04L65/80; H04N21/23605; H04N21/242; H04N21/4305; H04N7/54; H04N7/56
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
184 words
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.
Claim 2
Dependent Claim
60 words
A method in accordance with claim 1 comprising the further step of: providing a presentation time-stamp (PTS) extension in said isochronous data header to supplement a standard MPEG-2 PTS provided in said PES header, the combination of said PTS extension with the standard PTS enabling the time resolution for presenting isochronous data presentation units at said decoder to be increased.
Claim 3
Dependent Claim
21 words
A method in accordance with claim 2 wherein said PTS extension is provided at the beginning of said isochronous data header.
Claim 4
Dependent Claim
33 words
A method in accordance with claim 2 or 3 wherein said PTS extension is an eight bit extension derived from the eight most significant bits of the standard MPEG-2 nine bit PCR extension.
Claim 5
Independent Claim
37 words
A method in accordance with any of claims 2 to 4 wherein said eight bit PTS extension is combined with a standard 33-bit PTS to increase said time resolution from about 11.1 microseconds to about 74 nanoseconds.
Claim 6
Independent Claim
22 words
A method in accordance with any of the preceding claims wherein said isochronous data presentation units are each sixteen bits in length.
Claim 7
Independent Claim
100 words
A method for recovering isochronous data transmitted in accordance with the method of any of the preceding claims comprising the steps of: locating a PES header and an isochronous data header in a received data stream of said isochronous data transport packets; extracting program clock reference (PCR) values from said isochronous data transport packets; using said PCR values to recover said reference clock rate; extracting said clock increment value from said isochronous data header; using said extracted increment value to derive said isochronous data rate from said reference clock rate; and recovering said isochronous data at said isochronous data rate.
Claim 8
Dependent Claim
131 words
A method in accordance with claim 7 wherein prior to transmission of said high rate isochronous data in said MPEG-2 type transport stream, a presentation time-stamp (PTS) extension is provided in said isochronous data header to supplement a standard MPEG-2 PTS provided in said PES header, the combination of said PTS extension with the standard PTS enabling the time resolution for presenting isochronous data presentation units at said decoder to be increased, said method for recovering the isochronous data comprising the further steps of: extracting said standard PTS from said PES header; extracting said PTS extension from said isochronous data header; and using the extracted standard PTS and PTS extension to determine a correct time for commencing the presentation of the isochronous data presentation units contained in said received data stream.
Claim 9
Dependent Claim
21 words
A method in accordance with claim 8 wherein said PTS extension is provided at the beginning of said isochronous data header.
Claim 10
Dependent Claim
29 words
A method in accordance with claim 8 or 9 wherein said PTS extension is derived from the eight most significant bits of the standard MPEG-2 nine bit PCR extension.
Claim 11
Independent Claim
23 words
A method in accordance with any of claims 8 to 10 wherein said isochronous data presentation units are each sixteen bits in length.
Claim 12
Independent Claim
35 words
A method in accordance with any of the preceding claims comprising the further step of inserting PCR values into said isochronous data transport packets for use by said decoder in recovering said reference clock rate.
Claim 13
Dependent Claim
117 words
Apparatus for recovering isochronous data carried at an isochronous data rate in an MPEG-2 type transport stream comprising: 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.
Claim 14
Dependent Claim
70 words
Apparatus in accordance with claim 13 further comprising: means for extracting a presentation time-stamp (PTS) for the isochronous data from said PES header; means for extracting a PTS extension for the isochronous data from said isochronous data header and; means responsive to said extracted PTS and PTS extension for determining a correct time for commencing the presentation of isochronous data presentation units contained in said received data transport packet stream.
Claim 15
Dependent Claim
20 words
Apparatus in accordance with claim 14 wherein said PTS extension is extracted from the beginning of said isochronous data header.
Claim 16
Dependent Claim
20 words
Apparatus in accordance with claim 14 or 15 wherein said isochronous data presentation units are each sixteen bits in length.
Claim 17
Dependent Claim
117 words
Decoder apparatus for recovering information data from a data stream, said information being transmitted in said data stream at an information data rate, comprising: 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.
Claim 18
Dependent Claim
13 words
Apparatus in accordance with claim 17 wherein said increment value is an integer.
Claim 19
Dependent Claim
50 words
Apparatus in accordance with claim 17 or 18 wherein: said data stream is an MPEG-2 type transport stream; said system clock frequency is about 27 MHz; and said increment value is the nearest integer to the product of the information data rate and a modulus value N divided by 27,000,000.
Claim 20
Dependent Claim
13 words
Apparatus in accordance with claim 19 wherein said modulus value N = 536,868,000.
Claim 21
Dependent Claim
50 words
Apparatus in accordance with any of claims 17 to 20 wherein: said system clock frequency has a range of tolerance enabling said DDS clock to generate a substantially continuous range of reference clock rates from a system clock to recover information at any information rate within said substantially continuous range.
References Cited (Backward Citations)
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