Digital surveillance system with pre-event recording

• US 6,421,080 B1
• Filed: 11/05/1999
• Issued: 07/16/2002
• Est. Priority Date: 11/05/1999
• Status: Expired due to Term

• Current Assignee: Image Vault LLC
• Original Assignee: Image Vault LLC
• Inventors: Lambert, Tim A.
• Primary Examiner(s): DIEP, NHON THANH
• Application Number:
  US09/435,175
• Time in Patent Office: 984 Days
• Field of Search: H04/N.718, H04/N.947, 348/143, 348/150, 348/151, 348/152, 348/153, 348/154, 348/155, 348/156, 348/159
• US Class Current: 348/143
• CPC Class Codes: H04N 7/181 for receiving images from a plurality of remote sources

Abstract

An image recording system and method for use with a surveillance system having at least two cameras provides true pre-event recording for multiple input sources to improve video on demand storage control. More specifically, an image recording subsystem is connected to the cameras for receiving generated video images, and storing the received images in a temporary storage device having a storage capacity large enough to store video images generated over a predetermined period of time. The image recording subsystem is arranged to continuously record video images into the temporary storage device such as a cache memory, and in response to the occurrence of a triggering event, subsequently record the temporarily stored video images into a long-term storage device for later retrieval. The image recording system is arranged to determine the occurrence of overlapping triggering events, and automatically “rewind” the sequential long term storage process so that any images associated with an earlier triggering event but occurring in time after a later triggering event that have already been stored to long term storage are properly reordered to occur after any earlier occurring images associated with the later triggering event.

Claims

1. An image recording system for use with a surveillance system having at least two cameras comprising:

an image recording processor connected to the at least two video cameras for receiving generated video images and image creation time identifying information;

a temporary storage device connected to the image recording processor and having a storage capacity large enough to store video images generated over a predetermined period of time;

a long-term storage device connected to the image recording processor; and

a sensor arrangement for detecting an occurrence of a pre-defined triggering event associated with each camera, wherein the image recording processor is arranged to continuously record video images from each camera into the temporary storage device, and in response to the sensor arrangement detecting the occurrence of a triggering event associated with any of the at least two cameras, subsequently recording temporarily stored pre-event video images generated over a predetermined period of pre-event time by the associated camera into the long-term storage device.

3. The image recording system of claim 1 wherein the image recording processor is further arranged to determine an event starting time for each triggering event as being equal to a current time minus the predetermined period of pre-event time, and tag for recording to the long-term storage device any video image recorded in the temporary storage device having a creation time after the event starting time.

4. The image recording system of claim 1 wherein the temporary storage device comprises a cache memory.

5. The image recording system of claim 1 wherein the long term storage device comprises a disk data storage device.

6. The image recording system of claim 1 wherein the image recording processor comprises a video capture arrangement for capturing the received video images as digital image data.

7. The image recording system of claim 6 wherein the image recording processor is further arranged to compress the digital image data before recording in the temporary storage device.

8. The image recording system of claim 1 wherein the image recording processor is further arranged to determine the oldest video image stored in the temporary storage device based on the creation time identifying information, and automatically overwrite the oldest video image if the temporary storage device becomes filled.

2. An image recording system for use with a surveillance system having at least two cameras comprising:

an image recording processor connected to the at least two video cameras for receiving generated video images and image creation time identifying information;

a temporary storage device connected to the image recording processor and having a storage capacity large enough to store video images generated over a predetermined period of time;

a long-term storage device connected to the image recording processor; and

a sensor arrangement for detecting an occurrence of a pre-defined triggering event associated with each camera, wherein the image recording processor is arranged to continuously record video images from each camera into the temporary storage device, and in response to the sensor arrangement detecting the occurrence of a triggering event associated with any of the at least two cameras, subsequently recording temporarily stored video images generated by the associated camera into the long-term storage device,

wherein the sensor arrangement is arranged to detect an occurrence of overlapping pre-defined triggering events associated with different cameras, and the image recording processor is further arranged to subsequently record the temporarily stored video images generated by each camera associated with the detected triggering events into the long-term storage device, said image recording processor being further arranged to detect that images from an earlier triggering event but occurring after a starting time for a later triggering event have been recorded into the long-term storage device, and in response, automatically altering the sequence of images recorded to the long-term storage device to place the images associated with each overlapping triggering event in a combined oldest to latest time sequence.

9. A method for pre-event recording video images in a surveillance system having at least two cameras comprising:

receiving video images generated by the at least two video cameras and determining an image creation time for each received image;

recording the received video images in a temporary storage device having a storage capacity large enough to store video images generated over a predetermined period of time;

detecting an occurrence of a pre-defined triggering event associated with one of the cameras; and

in response to detecting the occurrence of the triggering event, subsequently recording temporarily stored pre-event video images generated over a predetermined period of pre-event time by the associated camera into a long-term storage device while continuing to maintain any images recorded in the temporary storage device generated by any camera not associated with triggering event.

14. The method of claim 9 further comprising determining an event starting time equal to a current time minus the predetermined period of pre-event time in response to detection of a triggering event, and tagging for recording in the long-term storage device any video image recorded in the temporary storage device having a creation time after the event starting time.

15. The method of claim 9 wherein recording the video images into a temporary storage device comprises storing the video images as image data in a cache memory.

16. The method of claim 9 wherein recording the temporarily stored video images into long-term storage comprises storing the video images as data in a disk data storage device.

17. The method of claim 9 further comprising capturing the received video images as digital image data.

18. The method of claim 17 further comprising compressing the digital image data before recording in the temporary storage device.

19. The method of claim 9 further comprising determining an oldest video image stored in the temporary storage device based on the creation time, and automatically overwriting the oldest video image if the temporary storage device becomes filled.

10. A method for pre-event recording video images in a surveillance system having at least two cameras comprising:

receiving video images generated by the at least two video cameras and determining an image creation time for each received image;

recording the received video images in a temporary storage device having a storage capacity large enough to store video images generated over a predetermined period of time;

detecting an occurrence of a pre-defined triggering event associated with one of the cameras;

in response to detecting the occurrence of the triggering event, subsequently recording temporarily stored video images generated by the associated camera into a long-term storage device while continuing to maintain any images recorded in the temporary storage device generated by any camera not associated with triggering event;

detecting an occurrence of overlapping pre-defined triggering events associated with different cameras;

in response to each triggering event, subsequently recording temporarily stored video images generated by each camera associated with the detected triggering events into a long-term storage device;

detecting that images from an earlier triggering event but occurring after a starting time for a later occurring triggering event have been recorded into the long-term storage device; and

in response, automatically altering the sequence of images recorded to the long-term storage device to place the images associated with each overlapping triggering event in a combined oldest to latest time sequence.

11. The method of claim 10 wherein detecting overlapping triggering events comprises detecting a new triggering event while long term recording for an earlier triggering event is enabled, and calculating a new starting time as being equal to the current time minus the amount of time already stored as part of the pre-event recording associated with this event.

12. The method of claim 11 further comprising analyzing each image stored in the temporary storage device and tagging for long-term storage any images associated with either event having a creation time occurring after the new starting time.

13. The method of claim 12 further comprising:

determining if any images in the cache that have been tagged for long-term storage have a later creation time than images that have been tagged for storage but have not yet been recorded to the long-term storage device;

setting the last image for recording in the long-term storage device to correspond to the last image with a time earlier than the new starting time; and

tagging all images stored in the temporary storage device that have a creation later than the new starting to indicate that the images have not yet been recorded to long-term storage.