Passive system and method for measuring the subjective quality of real-time media streams in a packet-switching network

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.

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.

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.

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.

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.

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.