# US 7,099,281 B1 · Passive system and method for measuring the subjective quality of real-time media streams in a packet-switching network > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,099,281 B1 - Document ID: US7099281B1 - Status: Granted - Kind: B1 - Application number: 09/822,043 - Filed: 2001-03-30 - Granted: 2006-08-29 - Earliest claimed: 2001-03-30 - Assignees: Verizon Corproate Services Group Inc.; Genuity Inc. - Inventors: Adrian Evans Conway - Web page: https://patentgrep.com/patent/US7099281B1 ## CPC - H04L 1/20: using signal quality detector - H04L 41/142: using statistical or mathematical methods - H04L 43/026: using flow identification - H04L 43/106: using time related information in packets, e.g. by adding timestamps - H04L 65/80: Responding to QoS - H04L 41/5009: Determining service level performance parameters or violations of service level contracts, e.g. violations of agreed response time or mean time between failures [MTBF] - H04L 41/5087: {wherein the managed service relates to voice services (management of VoIP services H04M7/0081)} - H04L 41/509: {wherein the managed service relates to media content delivery, e.g. audio, video or TV} - H04L 43/55: Testing of service level quality, e.g. simulating service usage - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract In accordance with the present invention, a portion of a packetized data stream is copied from a data network without interfering with the flow of the data in the network. A known test signal is then substituted for the information contained in each copied packet to prepare a pseudo-media packet stream. The known test signal is encoded and packetized using the same methods used for the copied data stream. The pseudo-media signal is then recovered from the pseudo-media stream using the same depacketizing and decoding methods to be used on the copied packetized data stream. The recovered signal is an accurate representation of the state of the media stream since it has gone through the same packetization/depacketization and encoding/decoding procedures and includes all of the same faults of the copied data stream. The subjective quality of the recovered signal is then measured providing an accurate measure of the subjective quality of the copied media stream. ## Claims ### Claim 1 A method for determining subjective quality of a packetized media data stream having packets of encoded data, each of said packets having a header portion and a data portion each having content, comprising the following steps: copying a portion of said packetized media data stream to obtain copied packets; replacing the content of the data portion of said copied packets with a packetized known test signal, said copied packets thereby comprising a pseudo-media stream; determining subjective quality of said pseudo-media stream; and using said subjective quality of said pseudo-media stream, to determine subjective quality of said packetized data stream wherein each packet copied from said packetized data stream is time stamped and said time stamping is used to control the temporal relationship between said copied portion of said packetized media data stream and said pseudo-media stream. ### Claim 2 (depends on 1) The method of claim 1 wherein the step of determining the subjective quality of the pseudo-media stream includes inputting the pseudo-media stream into a signal comparator with the packetized known test signal. ### Claim 3 A method for determining subjective quality of a packetized data stream having packets of encoded data, each of said packets having a header portion and a data portion each having some content, comprising the following steps: copying a portion of said packetized data stream to obtain copied packets; time stamping each packet included within said packetized data stream as it is copied; emptying data content of the data portion of each copied packet; loading a known test signal into each emptied packet; using said time stamping to maintain a temporal sequence of the loading to produce a pseudo-media stream; depacketizing and decoding said pseudo-media stream to obtain a pseudo-media signal; and determining said subjective quality of said pseudo-media signal that represents the subjective quality of said packetized data stream. ### Claim 4 (depends on 3) The method for determining subjective quality of a packetized data stream of claim 3, further comprising: determining packetization methodology used to packetize said data stream; and utilizing said packetization methodology to packetize said known test signal prior to loading said known test signal into said empty packets. ### Claim 5 (depends on 3) The method for determining subjective quality of a packetized data stream of claim 3, wherein each of said header portion contains a source identifier; and where said method further comprises separating said copied packetized data stream by source using said source identifier portion of each copied packet. ### Claim 6 (depends on 5) The method for determining subjective quality of a packetized data stream of claim 5, wherein said header portion of each copied packet includes a sequence number and said sequence number is used to determine which packetized known test signal packet replaces a copied media stream packet for said pseudo-media stream. ### Claim 7 (depends on 6) The method for determining subjective quality of a packetized data stream of claim 6, wherein order of the sequence numbers is maintained in substituting said packetized known test signal for the data contained in each copied packet. ### Claim 8 (depends on 3) The method of claim 3 wherein the step of determining the subjective quality of the pseudo-media stream includes inputting the pseudo-media stream into a signal comparator with the packetized known test signal. ### Claim 9 A method for determining subjective quality of a multi-media-source packetized data stream of packets each having data content, said method comprising the following steps; copying a portion of said multi-media-source packetized data stream to obtain copied packets; time stamping each of said copied packets to obtain time stamped copied packets; separating said copied packets according to their respective media sources to obtain a separated multi-media stream; selecting a media stream from said separated multi-media stream to obtain a selected media stream; identifying encoding/decoding and packetization/depacketization methods used on said selected media stream; replacing said data content of each copied packet in said selected media stream with a packetized known test signal while maintaining the sequence of said copied packets to produce a pseudo-media stream; depacketizing and decoding said pseudo-media stream using said time stamped copied packets to maintain the same temporal sequence as that with which the packets were originally copied to produce a pseudo-media signal; and measuring subjective quality of said pseudo-media signal to determine subjective quality of said selected media stream. ### Claim 10 (depends on 9) The method of claim 9 wherein the step of measuring the subjective quality of the pseudo-media stream includes inputting the pseudo-media stream into a signal comparator with the packetized known test signal. ### Claim 11 A system for measuring subjective quality of a real-time packetized media stream in a packet-switching network comprising: means for copying a portion of said media stream from said packet-switching network; means for emptying a payload portion of selected packets from said copied media stream portion, resulting in empty payload portions of the selected packets; means for reloading the empty payload portions of the selected packets with a known media signal to produce a pseudo-media stream; means for depacketizing and decoding said pseudo-media stream to produce a pseudo-media signal; and means for measuring the subjective quality of said pseudo-media signal and in turn the subjective quality of said packetized media stream. ### Claim 12 (depends on 11) The system for measuring subjective quality of a real-time packetized media stream in a packet-switching network of claim 11, further comprising: means for time stamping each packet copied from said media stream, and means for using said timestamp on said copied packet to coordinate the loading of said known media signal into said emptied packets. ### Claim 13 (depends on 11) The system for measuring subjective quality of a real-time packetized media stream in a packet-switching network of claim 11, further comprising: means for determining encoding and packetizing method used to prepare the packets in said copied media stream; and means for using said encoding and packetizing method to prepare the packets containing the known media signal. ### Claim 14 (depends on 11) A system for measuring subjective quality of a real-time packetized media stream in a packet-switching network of claim 11, further comprising: means for determining decoding and depacketizing methods to be used with said copied media stream; and means for using said decoding and depacketizing methods on said known media signal. ### Claim 15 (depends on 11) A system for measuring subjective quality of a real-time packetized media stream in a packet-switching network of claim 11, further comprising: means for determining the encoding/decoding and packetization/depacketization methods used with the copied packets in said media stream; and means for using encoding/decoding and packetization/depacketization methods in handling the packets of the known media signal in the preparation of said pseudo-media stream. ### Claim 16 (depends on 11) The system of claim 11 wherein the means for measuring the subjective quality of said pseudo-media signal comprises a signal comparator. ### Claim 17 An apparatus for measuring subjective quality of information contained in a packetized data stream comprising: a first device that copies a portion of said packetized data stream; a second device that substitutes a known test signal for the information contained in the copied portion of said packetized data stream to produce a pseudo-media stream; a third device that depacketizes and decodes said pseudo-media stream to produce a pseudo-media signal; and a fourth device that determines subjective quality of said pseudo-media signal and subjective quality of the information contained in said packetized data stream. ### Claim 18 (depends on 17) The apparatus for measuring subjective quality of information contained in a packetized data stream of claim 17, wherein said second device includes: means for emptying the information content of each of said copied packet; and means for loading a packetized known test signal into each of said empty packets. ### Claim 19 (depends on 17) The apparatus of claim 17 wherein said fourth device comprises a signal comparator. ### Claim 20 An apparatus for measuring subjective quality of the information contained in a single packetized data stream included in a multi-source packetized data stream comprising: a first device for copying a portion of said multi-source packetized data stream; a second device for separating a single packetized data stream from said copied portion of said multi-source packetized data stream; a third device for replacing the information content of each copied packet with a known signal to create a pseudo-media stream; a fourth device for depacketizing and decoding said pseudo-media stream to produce a pseudo-media signal; and a fifth device for measuring the subjective quality of said pseudo-media signal and in-turn the subjective quality of the information contained in said single packetized data stream. ### Claim 21 (depends on 20) An apparatus for measuring the subjective quality of the information contained in a single packetized data stream included in a multi-source packetized data streaming as set forth in claim 20, wherein said second device reads a source identifier contained in each copied packet; and diverts selected packets having a common source identifier. ### Claim 22 (depends on 20) An apparatus for measuring the subjective quality of the information contained in a single packetized data stream included in a multi-source packetized data streaming as set forth in claim 20 wherein said third device empties the information content of each packet of said separated single packetized data stream and loads a packetized known test signal into said empty packets. ### Claim 23 (depends on 20) An apparatus for measuring subjective quality of the information contained in a single packetized data stream included in a multi-source packetized data streaming as set forth in claim 20 including: means for identifying the encoding/decoding and packetization/depacketization methods used on and to be used on the information contained in said single packetized data stream, and means for using said encoding and packetization methods in the preparation of said pseudo-media stream; and means for using said decoding and depacketization methods in the preparation of said pseudo-media signal. ### Claim 24 (depends on 20) The apparatus of claim 20 wherein said fifth device comprises a signal comparator. ### Claim 25 An apparatus that measures subjective quality of information contained in a packetized media stream containing a plurality of packets, each of said packets having a header portion and a payload portion, comprising: a first device that copies a segment of said packetized media stream; a second device that substitutes a known test signal for the payload portion of said packets in said copied media stream segment and creates a pseudo-media stream; a third device that depacketizes and decodes said pseudo-media stream to produce a pseudo-media signal; and a fourth device that determines subjective quality of said pseudo-media signal and subjective quality of the information contained in said packetized media stream. ### Claim 26 (depends on 25) The apparatus of claim 25, wherein said copied segment of the packetized media stream is stored in a memory. ### Claim 27 (depends on 25) The apparatus of claim 25, wherein said second device determines the encoding scheme of said packetized media stream. ### Claim 28 (depends on 25) The apparatus of claim 25, wherein the second device determines the packetization scheme of said packetized media stream. ### Claim 29 (depends on 25) The apparatus of claim 25, wherein said second device encodes and packetizes the known test signal. ### Claim 30 (depends on 25) The apparatus of claim 25 wherein said fourth device comprises a signal comparator.