US5835730A — MPEG packet header compression for television mod…

Claim 1

Independent Claim 141 words

A method for processing consecutive fixed length packets of a packet stream to simulate a computer disk drive output format which requires a temporal gap between successive ones of said packets, including a first packet and an adjacent packet, comprising the steps of: locating a packet header for said first packet; and performing at least one of a deleting and coding step to reduce an amount of data in said first packet corresponding to said temporal gas, where said deleting step comprises deleting at least one known or calculable fixed length field from said header and said coding step comprises coding an N-bit packet identifier from said header into an M-bit reference value, where M<N; wherein said at least one deleting and coding step compresses said header to provide said gap between data from said first packet and said adjacent packet.

Claim 2

Independent Claim 141 words

A method for processing consecutive fixed length packets of a packet stream to simulate a computer disk drive output format which requires a temporal gap between successive ones of said packets, including a first packet and an adjacent packet, comprising the steps of: locating a packet header for said first packet; and performing at least one of a deleting and coding step to reduce an amount of data in said first packet corresponding to said temporal gas, where said deleting step comprises deleting at least one known or calculable fixed length field from said header and said coding step comprises coding an N-bit packet identifier from said header into an M-bit reference value, where M<N; wherein said at least one deleting and coding step compresses said header to provide said gap between data from said first packet and said adjacent packet.

Claim 3

Dependent Claim 35 words

A method in accordance with claim 1 wherein both said deleting and coding steps are performed, said deleting step deletes a total of K-bits from said header, and the gap is equivalent to K+M-N bits.

Claim 4

Dependent Claim 54 words

A method in accordance with claim 2 comprising the further steps of decompressing said header by: inserting said at least one fixed length field back into said header; decoding said M-bit reference value to recover said N-bit packet identifier; and substituting said M-bit reference value in said header with said recovered N-bit packet identifier.

Claim 5

Dependent Claim 37 words

A method in accordance with claim 2 wherein said packet stream is an MPEG Transport Stream, said fixed length field is a K-bit MPEG synchronization byte, and said N-bit packet identifier is an MPEG packet identifier (PID).

Claim 6

Dependent Claim 37 words

A method in accordance with claim 1 wherein said packet stream is an ATM cell stream and said N-bit packet identifier is at least one of a virtual path identifier (VPI) and a virtual circuit identifier (VCI).

Claim 7

Dependent Claim 32 words

A method in accordance with claim 1 wherein said fixed length field is at least one of a calculable ATM header error correction (HEC) field and a generic flow control (GFC) field.

Claim 8

Independent Claim 73 words

A method for compressing a packet header from a first data packet of a digital packet stream comprising the steps of: deleting a fixed length field from said header; and coding an N-bit packet identifier from said header into an M-bit reference value, where M<N; wherein said deleting and coding steps reduce an amount of data in said first packet corresponding to a temporal gap between said first packet and an adjacent packet.

Claim 9

Independent Claim 73 words

A method for compressing a packet header from a first data packet of a digital packet stream comprising the steps of: deleting a fixed length field from said header; and coding an N-bit packet identifier from said header into an M-bit reference value, where M<N; wherein said deleting and coding steps reduce an amount of data in said first packet corresponding to a temporal gap between said first packet and an adjacent packet.

Claim 10

Dependent Claim 51 words

A method in accordance with claim 7 comprising the further steps of decompressing said header by: inserting said fixed length byte back into said header; decoding said M-bit reference value to recover said N-bit packet identifier; and substituting said M-bit reference value in said header with said recovered N-bit packet identifier.

Claim 11

Dependent Claim 146 words

Apparatus for receiving a packet stream having fixed length packets and selectively processing data carried in said stream for output to a computer, comprising: a receiver for recovering said packet stream; a packet identifier filter for selecting particular packets from the recovered packet stream; a disk controller for receiving the packets selected by said filter and managing the transfer of packet data from said packets to and from a buffer; a data bus coupled to said disk controller for communicating said packet data from said buffer to said computer; and a data compression stage prior to said disk controller for compressing packets from the recovered packet stream in order to provide a temporal gap between data carried by successive packets to be provided to the disk controller; said temporal gap corresponding to a gap that is required by said disk controller to process said successive packets.

Claim 12

Dependent Claim 146 words

Apparatus for receiving a packet stream having fixed length packets and selectively processing data carried in said stream for output to a computer, comprising: a receiver for recovering said packet stream; a packet identifier filter for selecting particular packets from the recovered packet stream; a disk controller for receiving the packets selected by said filter and managing the transfer of packet data from said packets to and from a buffer; a data bus coupled to said disk controller for communicating said packet data from said buffer to said computer; and a data compression stage prior to said disk controller for compressing packets from the recovered packet stream in order to provide a temporal gap between data carried by successive packets to be provided to the disk controller; said temporal gap corresponding to a gap that is required by said disk controller to process said successive packets.

Claim 13

Dependent Claim 21 words

Apparatus in accordance with claim 9 wherein said data compression stage compresses header portions of packets provided to said disk controller.

Claim 14

Dependent Claim 18 words

Apparatus in accordance with claim 10 wherein said header portions comprise transport headers of an MPEG Transport Stream.

Claim 15

Dependent Claim 39 words

Apparatus in accordance with claim 11 wherein said compression stage compresses a transport header by deleting a synchronization field therefrom, and coding an N-bit MPEG packet identifier (PID) from the transport header into an M-bit PID reference, where M<N.

Claim 16

Dependent Claim 24 words

Apparatus in accordance with claim 12 wherein said compression stage comprises a lookup table for coding said N-bit PID into said M-bit PID reference.

Claim 17

Dependent Claim 32 words

Apparatus in accordance with claim 12 wherein said synchronization byte has a known value and said N-bit PID is recoverable from said M-bit PID reference, whereby said compression stage provides lossless compression.

Claim 18

Dependent Claim 62 words

Apparatus in accordance with claim 12 wherein said compression stage uses index coding to provide said M-bit PID reference, in which 2 M /2 possible PID references are designated by a most significant bit (MSB) having a first binary value and the remaining 2 M /2 possible PID references are designated by a most significant bit (MSB) having a second binary value.

Claim 19

Dependent Claim 23 words

Apparatus in accordance with claim 9 wherein said data compression stage is coupled to receive and compress the packets selected by said filter.

Claim 20

Dependent Claim 18 words

Apparatus in accordance with claim 10 wherein said header portions comprise cell headers of an ATM cell stream.

Claim 21

Dependent Claim 74 words

Apparatus in accordance with claim 17 wherein said compression stage compresses a cell header by performing at least one of a deleting and coding step, where said deleting step comprises deleting at least one fixed length field from said header and said coding step comprises coding at least one of an N-bit virtual path identifier (VPI) and an N-bit virtual circuit identifier (VCI) from the transport header into an M-bit reference value, where M<N.

Claim 22

Dependent Claim 29 words

Apparatus in accordance with claim 18 wherein said compression stage comprises a lookup table for coding said at least one N-bit VPI or VCI into said M-bit reference value.

Claim 23

Dependent Claim 36 words

Apparatus in accordance with claim 18 wherein said at least one fixed length field comprises at least one of an ATM header error correction (HEC) field, a generic flow control (GFC) field and a VPI field.

Claim 24

Dependent Claim 41 words

Apparatus in accordance with claim 18 wherein said at least one fixed length field has a calculable value and said at least one N-bit VPI or VCI is recoverable from said M-bit PID reference, whereby said compression stage provides lossless compression.

Claim 25

Dependent Claim 62 words

Apparatus in accordance with claim 18 wherein said compression stage uses index coding to provide said M-bit reference value, in which 2 M m/2 possible reference values are designated by a most significant bit (MSB) having a first binary value and the remaining 2 M /2 possible reference values are designated by a most significant bit (MSB) having a second binary value.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	2001-11-09	2002-05-11	2002-11-10	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2005-11-09	2006-05-11	2006-11-10	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2009-11-09	2010-05-11	2010-11-10	$7700.00	Window Closed / Lapsed

MPEG packet header compression for television modems

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