Detecting content based defects in a video stream

• US 6,906,743 B1
• Filed: 01/13/1999
• Issued: 06/14/2005
• Est. Priority Date: 01/13/1999
• Status: Expired due to Term

• Current Assignee: Tektronix Incorporated (Fortive Corp.)
• Original Assignee: Tektronix Incorporated (Fortive Corp.)
• Inventors: Maurer, Steven D.
• Primary Examiner(s): Kostak, Victor R.
• Application Number:
  US09/231,128
• Time in Patent Office: 2,344 Days
• Field of Search: 348/700, 348/701, 348/192, 348/193, 348/180, 348/184, 348/722, 725/22, 725/107, 725/108
• US Class Current: 348/180
• CPC Class Codes: H04N 7/0112 one of the standards corresponding to a cinematograph film standard

Abstract

A method of detecting content based defects in previously compressed video streams decodes a video channel from the compressed video streams and performs a match on a frame/field basis between each frame/field of the video channel and a black frame/field and/or a previous frame/field to detect missing frames/fields and/or duplicate frames/fields. The number of consecutive missing and/or duplicate frames/fields are counted and an alarm signal is generated when the count exceeds a specified value. A beat pattern detector may be used to differentiate between 3/2 pulldown and other duplicate frame/field content errors, and a graphics detector may be used to differentiate between lettering/graphics stills and other duplicate frame/field content errors.

Claims

1. An apparatus for detecting content based defects in a video stream comprising:

a plurality of detectors, each having an input coupled in parallel to receive the video stream and having an output, the output from each detector providing a separate specified content characteristic of the video stream;

means for determining whether one of the separate specified content characteristics meet a predetermined alarm criterion; and

means for reporting an error when the predetermined alarm criterion is met.

2. The apparatus as recited in claim 1 wherein the detectors include a duplicate field detector, a black field detector, a graphics detector, a closed caption detector, a motion detector and a brightness detector each having an input coupled to receive the video stream and an output coupled to provide the separate specified content characteristic to the determining means.

3. The apparatus as recited in claim 2 further comprising a beat pattern detector having an input coupled to the output of the duplicate field detector and having an output coupled to provide a pulldown indicator signal as the separate specified content characteristic to the determining means.

4. The apparatus as recited in claim 2 wherein the duplicate field detector comprises a picture match module for matching each field of the video stream with a black field to provide an output for each match that occurs indicative of a missing field in the video stream as the separate specified content characteristic.

5. The apparatus as recited in claim 2 wherein the duplicate field detector comprises a picture match module for matching each field of the video stream with a corresponding field from a previous frame of the video stream to provide an output for each match that occurs indicative of a duplicate field in the video stream as the separate specified content characteristic.

6. The apparatus as recited in claim 5 wherein the detectors further include a beat pattern detector having an input coupled to the output of the picture match module and having an output coupled to the determining means, the beat pattern detector providing a pulldown indication signal as the separate specified content characteristic.

7. The apparatus as recited in claim 2 wherein the graphics detector provides a graphics signal indicative of when duplicate fields result from graphic fields in the video stream as the separate specified content characteristic.

8. The apparatus as recited in claims 4 or 5 wherein the determining means comprises:

a counter for counting each output from the picture match module to provide a count output; and

means for indicating the error when the count output reaches a designated number as the specified alarm criterion.

9. The apparatus as recited in claim 6 wherein the determining means comprises:

a counter for counting each output from the picture match module to provide a count output; and

means for indicating the error when the count output reaches a designated number that is not related to pulldown.

10. The apparatus as recited in claim 7 wherein the determining means comprises:

a counter for counting each output from the graphics detector to provide a count output; and

means for indicating the error when the count output reaches a designated number that is not related to lettering/graphic video.

11. The apparatus as recited in claim 2 wherein the closed caption detector provides an indication of the status of closed caption as the separate specified content characteristic.

12. The apparatus as recited in claim 2 wherein the motion detector provides an indication of missing fields as the separate specified content characteristic.

13. The apparatus as recited in claim 2 wherein the brightness detector provides a level signal as the separate specified content characteristic.

14. The apparatus as recited in claims 1 or 2 wherein the determining means comprises logic having as inputs the outputs from the detectors to provide the error with a given priority.

15. A method of detecting content based defects in a video stream comprising:

detecting a specified content characteristic in the video stream using a plurality of detectors, each having an input coupled in parallel to receive the video stream and having an output coupled to the determining means, the output from each detector providing a separate specified content characteristic as the specified content characteristic;

determining whether the specified content characteristic meets a predetermined alarm criterion; and

reporting an error when the predetermined alarm criterion is met.

16. The method as recited in claim 15 wherein the detectors are selected from the group consisting of a duplicate field detector, a black field detector, a graphics detector, a closed caption detector, a motion detector, and a brightness detector, each detector having an input coupled to receive the video stream and an output for providing an output signal representative of the separate specified content characteristic, the output signal being input to the determining step.

17. The method as recited in claim 16 wherein the detecting step further comprises the step of detecting a beat pattern to provide a pulldown indication output signal when the output signal from the duplicate field detector indicates a duplicate field at specified regular intervals, the output being coupled to provide the pulldown indication signal to the determining step as the separate specified content characteristic.