In-service video quality measurement system utilizing an arbitrary bandwidth ancillary data channel

• US 6,496,221 B1
• Filed: 11/01/1999
• Issued: 12/17/2002
• Est. Priority Date: 11/02/1998
• Status: Expired due to Fees

• Current Assignee: United States Secretary of Commerce
• Original Assignee: THE GOVERNMENT OF THE UNITED STATES OF AMERICA, AS REPRESENTED BY THE SECRETARY OF COMMERCE
• Inventors: Wolf, Stephen, Pinson, Margaret H.
• Primary Examiner(s): Miller, John
• Assistant Examiner(s): Yenke, Brian P
• Application Number:
  US09/431,160
• Time in Patent Office: 1,142 Days
• Field of Search: H04/N 1.700, H04/N 1.702, 348/180, 348/181, 348/182, 348/183, 348/184, 348/192, 348/193, 348/194, 455/67.1, 455/67.3, 455/67.7, 455/69
• US Class Current: 348/192
• CPC Class Codes: H04N 17/00 Diagnosis, testing or measuring for television systems or their details
• CPC Class Codes: H04N 17/02 for colour television signals

Abstract

An apparatus for measuring the quality of a video transmission or storage system when the input and output of the system may be spatially separated, when the apparatus might not have a priori knowledge of the input video, and when there exists an ancillary data channel that can be used by the apparatus. The apparatus makes continuous quality measurements by extracting features from sequences of processed input and output video frames, communicating the extracted features between the input and the output ends using an ancillary data channel of arbitrary and possible variable bandwidth, computing individual video quality parameters from the communicated features that are indicative of the various perceptual dimensions of video quality (e.g., spatial, temporal, color), and finally calculating a composite video quality score by combining the individual video quality parameters. The accuracy of the composite video quality score generated by the apparatus depends on the bandwidth of the ancillary data channel used to communicate the extracted features, with higher capacity ancillary data channels producing greater accuracies than lower capacity ancillary data channels.

Claims

1. A method of measuring in-service video quality of a video transmission system comprising the steps of:

(a) extracting features from sequences of processed input and output video frames;

(b) communicating the extracted features of the input video frames between an input and an output of an ancillary data channel;

(c) computing individual video quality parameters from the extracted features which are indicative of perceptual dimensions of video quality;

(d) calculating a plurality of composite video quality scores by combining sets of the individual quality parameters; and

(e) selecting the set of video quality parameters having the highest video quality score, wherein

the individual video quality parameters comprise an arithmetic product of spatial and temporal features of the input video frames and an arithmetic product of spatial and temporal features of the output video frames.

2. A method according to claim 1, wherein the individual quality parameters computed in step (c) further comprise at least one of spatial, temporal, color, brightness and contrast features.

3. A method according to claim 2, wherein the ancillary data channel has a variable bandwidth.

4. A method according to claim 3, further comprising

determining the maximum data bandwidth of the ancillary data channel at least prior to communicating the extracted features in step (b).

5. A method according to claim 4, further comprising

providing an ancillary bandwidth input;

and

setting the bandwidth of the ancillary data channel equal to the ancillary bandwidth input if the ancillary bandwidth input is less than or equal to the maximum data bandwidth of the ancillary data channel.

6. A method according to claim 1, further comprising

creating a copy of a video input stream and a video output stream;

coupling an input calibration processor and an output calibration processor nonintrusively to the copy of the video input stream and video output stream, respectively.

7. A method according to claim 6, wherein:

the input calibration processor

1) estimates a video delay of the video transmission system; and

2) produces a calibrated video input stream which is synchronized with the video output stream copy; and

the output calibration processor

1) estimates gain, offset level, and spatial shift of the video transmission system; and

2) produces a calibrated video output stream which is gain adjusted, level shifted, and spatially shifted to match the video input stream copy.

8. A method according to claim 7, wherein

the input calibration and output calibration is performed on image fields.

9. A method of measuring in-service video quality of a video transmission system, comprising:

extracting features from sequences of processed input and output video frames;

communicating the extracted features of the input video frames between an input and an output of an ancillary data channel;

computing individual video quality parameters from the extracted features which are indicative of perceptual dimensions of video quality;

calculating a plurality of composite video quality scores by combining sets of the individual quality parameters;

selecting the set of video quality parameters having the highest video quality score; and

determining the possible combination of dimensions (Δ

h×

Δ

v×

Δ

t) of the extracted features which do not exceed the lesser of;

1) a bandwidth of the ancillary data channel;

or

2) the bandwidth of an ancillary bandwidth input.

10. A method according to claim 9, further comprising:

varying the dimensions (Δ

h×

Δ

v×

Δ

t) of the extracted features in an inverse proportion to a change in bandwidth size of the ancillary data channel.

11. An apparatus for in-service video quality measurement of a video transmission system, said apparatus comprising:

extracting means for extracting features from sequences of processed input and output video frames;

an ancillary data channel having an input and an output;

communicating means for communicating features of the input video frames extracted by said extracting means between the input and the output of said ancillary data channel;

computing means for computing individual quality parameters from the extracted features which are indicative of perceptual dimensions of video quality;

calculating means for calculating a plurality of composite video scores by combining sets of the individual quality parameters; and

optimizing means for selecting the set of individual quality parameters having the highest video quality score, wherein

the individual video quality parameters comprise an arithmetic product of spatial and temporal features of the input video frames and an arithmetic product of spatial and temporal features of the output video frames.

12. An apparatus according to claim 11, wherein

said ancillary data channel has a variable bandwidth.

13. An apparatus according to claim 12, wherein said communicating means includes means for determining a maximum value of the bandwidth of said ancillary data channel.

14. An apparatus according to claim 13, further comprising:

an ancillary bandwidth input; and

the bandwidth of said ancillary data channel is set equal to the bandwidth of said ancillary bandwidth input, if the bandwidth of said ancillary bandwidth input is less than or equal to the maximum value of the bandwidth of said ancillary data channel.

15. An apparatus according to claim 11, further comprising:

an input coupler and an output coupler;

said input coupler and said output coupler are coupled respectively to a video input stream and a video output stream to produce a copy of each video stream;

an input calibration processor, which is nonintrusively coupled to said input coupler; and

an output calibration processor, which is nonintrusively coupled to said output coupler;

said input calibration processor and said output calibration processor process the copy of the video input stream and video output stream, respectively.

16. An apparatus according to claim 15, wherein said computing means includes a video quality processor.

17. An apparatus according to claim 16, wherein said input calibration processor and said output calibration processor process image fields.

18. An apparatus for in-service video quality measurement of a video transmission system, comprising:

an extracting means for extracting features from sequences of processed input and output video frames;

an ancillary data channel having an input and an output;

a communicating means for communicating features of the input video frames extracted by said extracting means between the input and the output of the ancillary data channel;

a computing means for computing individual quality parameters from the extracted features which are indicative of perceptual dimensions of video quality;

a calculating means for calculating a plurality of composite video scores by combinations of sets of the individual quality parameters; and

an optimizing means for selecting the set of individual quality parameters having the highest video quality score, wherein

said extracting means includes a means for changing a size of the dimensions (Δ

h×

Δ

v×

Δ

t) of features extracted by said extracting means which is inversely proportional to a bandwidth of said ancillary data channel.

19. An apparatus according to claim 18, wherein said computing means includes means for detecting individual quality parameters for at least one of spatial, temporal, color, spatial-temporal, brightness, and contrast.

20. An apparatus according to claim 19, wherein said extracting means includes means for determining a plurality of combinations of dimensions (Δ

h×

Δ

v×

Δ

t) of features extracted by said extracting means which do not exceed the lesser of;

1) the bandwidth of the ancillary data channel;

or

2) the bandwidth of said ancillary bandwidth input.