Detecting scene changes

• US 5,471,239 A
• Filed: 12/08/1993
• Issued: 11/28/1995
• Est. Priority Date: 03/26/1992
• Status: Expired due to Fees

• Current Assignee: Solid State Logic Limited (Audiotonix Ltd.)
• Original Assignee: Solid State Logic Limited (Audiotonix Ltd.)
• Inventors: Randall, Bruce W., Hill, Philip N. C.
• Primary Examiner(s): Britton, Howard W.
• Application Number:
  US08/142,461
• Time in Patent Office: 720 Days
• Field of Search: 348/154, 348/155, 348/700, 348/701
• US Class Current: 348/155
• CPC Class Codes: G08B 13/19602 Image analysis to detect motion of the intruder, e.g. by frame subtraction
• CPC Class Codes: G08B 13/19667 Details realated to data compression, encryption or encoding, e.g. resolution modes for reducing data volume to lower transmission bandwidth or memory requirements
• CPC Class Codes: G08B 13/19676 Temporary storage, e.g. cyclic memory, buffer storage on pre-alarm
• CPC Class Codes: G08B 13/19691 Signalling events for better perception by user, e.g. indicating alarms by making display brighter, adding text, creating a sound
• CPC Class Codes: G11B 2220/20 Disc-shaped record carriers
• CPC Class Codes: G11B 2220/90 Tape-like record carriers
• CPC Class Codes: G11B 27/034 on discs G11B27/036, G11B27/038 take precedence
• CPC Class Codes: G11B 27/10 Indexing; Addressing; Timing or synchronising; Measuring tape travel
• CPC Class Codes: G11B 27/28 by using information signals recorded by the same method as the main recording G11B27/22 takes precedence
• CPC Class Codes: G11B 27/3045 superimposed on the recorded main signal, e.g. burn-in-time code
• CPC Class Codes: G11B 27/34 Indicating arrangements indicating means incorporated in magazine or cassette G11B23/046 and G11B23/0875; indicating measured values in general G01D
• CPC Class Codes: H04N 19/00 Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
• CPC Class Codes: H04N 19/142 Detection of scene cut or scene change
• CPC Class Codes: H04N 19/179 the unit being a scene or a shot
• CPC Class Codes: H04N 19/503 involving temporal prediction adaptive coding with adaptive selection between spatial and temporal predictive coding H04N19/107; adaptive coding with adaptive selection among a plurality of temporal predictive coding modes H04N19/109
• CPC Class Codes: H04N 19/87 involving scene cut or scene change detection in combination with video compression
• CPC Class Codes: H04N 5/147 Scene change detection
• CPC Class Codes: H04N 5/262 Studio circuits, e.g. for mixing, switching-over, change of character of image, other special effects ; Cameras specially adapted for the electronic generation of special effects
• CPC Class Codes: H04N 5/272 Means for inserting a foreground image in a background image, i.e. inlay, outlay
• CPC Class Codes: H04N 5/781 on disks or drums
• CPC Class Codes: H04N 5/907 : using static stores, e.g. storage tubes or semiconductor memories H04N5/91 takes precedence
• CPC Class Codes: H04N 9/8047 : using transform coding

Abstract

Scene changes in a video sequence are detected by generating data representing the amount of information present in each video frame. This information is processed in such a way that significant changes in the information content are identified as positions where scene changes are likely to occur. The amount of information present in each video frame is determined by compressing the video in accordance with a spatial algorithm, such as JPEG. Under such compression techniques, the amount of data present after compression will vary, depending upon the amount of information present in the original scenes. Thus, for each frame, information is available identifying the amount of data present in the compressed video. This information is analysed on a frame-by-frame basis, providing information identifying the presence of scene changes. In a facility for editing the video, or editing audio for synchronisation against a video track, the scene change information may be displayed to an operator. In a security system, the occurrence of a scene change may be identified as an intruder entering an area observed by a camera. On detecting an intruder, in this way, various measures may be taken, such as activating a video tap recorder.

Claims

1. A method of detecting the position of a scene change in a video frame sequence, said method comprising the steps of:

generating data representing the amount of information present in each video frame;

processing said data to locate significant changes in said amount of information between frames, and

identifying the frame position of said significant changes, so as to identify the frame position of likely scene changes.

2. A method as in claim 1, wherein digital signal values (X) are generated representing the amount of information present in each frame and said values are differentiated with respect to frame times to provide an indication of the presence of a scene change.

3. A method as in claim 1, wherein said video frame sequence is derived from edited video, and scene changes are detected to facilitate the editing of an audio track.

4. A method as in claim 1, wherein said video frame sequence is derived from a source recording, and scene change detection is implemented to facilitate the editing of said video frame sequence.

5. A method as in claim 1, wherein said video frame sequence is derived from a camera and the scene change detection is performed to identify changes to the scene observed by said camera.

6. A method as in claim 5, wherein a scene change detected from said camera results in measures being taken to identify the existence of an intruder.

7. A method as in claim 6, wherein a video tape recorder is activated on the detection of said intruder.

8. A method as in claim 7, where the activation of said video tape recorder includes the modification of recording procedures for said video tape recorder, so as to enhance the quality of images recorded thereby.

9. A method as is claim 1, wherein the video frame sequence includes video field signals that are interlaced and wherein the amount of information present in each video frame is determined by determining the amount of information present in each video field.

10. A method as in claim 1 or 2, wherein the amount of information is determined by compressing video data nd assessing how much data is present after compression.

11. A method as in claim 10, wherein the video data is compressed in accordance with a spatial compression algorithm.

12. A method as in claim 11 wherein said spatial compression algorithm compresses each video field or frame and information is generated representing the amount of information present in said field or frame, after compression.

13. A method as in claim 11, wherein JPEG compression is used to compress data within each field or frame.

14. A method as in claim 11, wherein said compression algorithm divides data relating to a field or a frame into a plurality of areas.

15. A method as in claim 14, wherein said areas are processed to determine the frequency components of signals derived from said areas.

16. A method as in claim 15, wherein said frequency components are truncated to facilitate further compression.

17. A method as in claim 16, wherein said truncated frequency components are coded in accordance with a statistically related coding scheme, such as Huffman coding, to provide further data compression.

18. Apparatus for detecting the position of a scene change in a video frame sequence, said apparatus comprising:

means for generating data representing the amount of information present in each video frame;

processing means for processing said data to locate significant changes in said amount of information between frames; and

display means for identifying the frame position of said significant changes, so as to identify the frame position of likely scene changes.

19. An edit suite for editing audio signals to a previously edited video track, including scene change detection apparatus according to claim 18.

20. An edit suite for editing video clips, including scene change detection apparatus according to claim 18.

21. A surveillance system including a camera arranged to observe a scene, scene change detection apparatus according to claim 18 and means for generating an output signal on detecting a change of scene.

22. A surveillance system as in claim 21, including a video tape recorder for recording an output from said camera.

23. A surveillance system as in claim 22, wherein said video tape recorder only records when an intruder is detected.

24. A surveillance system as in claim 22, wherein the operating characteristics of the video recorder are modified, so as to record pictures of improved quality, when an intruder is detected.

25. Apparatus as in claim 18, wherein said means for generating data includes compressing means for compressing video data.

26. Apparatus as in claim 18 or 25, wherein said compression means includes means for compressing said video data in accordance with a spatial compression algorithm.

27. Apparatus as in claim 26 wherein said compression means effects JPEG spatial compression.