Television – Monitoring – testing – or measuring – Transmission path testing
Reexamination Certificate
1998-09-08
2001-06-12
Eisenzopf, Reinhard J. (Department: 2614)
Television
Monitoring, testing, or measuring
Transmission path testing
C348S180000, C348S519000
Reexamination Certificate
active
06246435
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to the analyzing of the quality of transmitted video images, and more particularly to an in-service, realtime picture quality analysis method that does not require a broadband reference video signal at a test point.
Currently picture quality measurements are based upon a full bandwidth picture differencing method using a human vision model algorithm, such as the Sarnoff Corporation JNDmetrix™ algorithm. In this method a reference (original) video signal is compared against a test (impaired) video signal. This requires the full bandwidth reference and test video signals to be available at a test point in order to perform picture quality analysis.
There are two ways the reference video signal may be made available at the test point:
1. Pre-storing the reference video signal on the test system—this requires prior knowledge of reference video scenes which limits its usefulness to out-of-service and non-realtime applications; and
2. Sending the reference video signal to the test point over a low bandwidth data link—this requires a dedicated data link to transport the reference video signal to the test point on demand as well as posing bandwidth limitation issues, and therefore is not useful for realtime picture quality analysis.
What is desired is a method of picture quality analysis that may be performed real time while the system under test is in-service.
SUMMARY OF THE INVENTION
Accordingly the present invention provides an in-service, realtime picture quality analysis method by comparing parameters that characterize the reference video signal with the same parameters for the test video signal. The reference video signal is input to a compression encoder and to a parameter characterization module. Specific parameters are extracted from the reference video signal and input to a parameter insertion module. The parameter insertion module inserts the parameters as ancillary data in the compressed data transport stream from the compression encoder. At the test point the transport stream is input to a compression decoder to recover the test video signal, and also is input to a parameter extraction module that extracts the transmitted parameters from the ancillary data. The test video signal is input to a parameter characterization module like the one at the transmission end and the same parameters are generated for the test video signal that correspond to the extracted parameters. These two sets of parameters are then input to a picture quality analyzer module for comparison, and any differences are reported as a picture quality rating.
The objects, advantages and other novel features of the present invention are apparent from the following detailed description when read in conjunction with the appended claims and attached drawing.
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patent: 4682246 (1987-07-01), Efron et al.
patent: 5260788 (1993-11-01), Takano et al.
patent: 5446492 (1995-08-01), Wolf et al.
patent: 5694174 (1997-12-01), Suzuki
patent: 5764284 (1998-06-01), Stoker
patent: 5920572 (1999-06-01), Washington et al.
patent: 5940124 (1999-08-01), Janko et al.
Eisenzopf Reinhard J.
Gray Francis I.
Tektronix Inc.
Tran Trang U.
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