Memory Management In Event Recording Systems

• US 20090222163A1
• Filed: 12/07/2006
• Published: 09/03/2009
• Est. Priority Date: 12/08/2005
• Status: Active Grant

• Current Assignee: SmartDrive Systems, Inc. (Solera Holdings Incorporated)
• Original Assignee: Smart Drive Systems, Inc.
• Inventors: Plante, James
• Granted Patent: US 8,374,746 B2
• Time in Patent Office: Days
• US Class Current: 701/35
• CPC Class Codes: G07C 5/02 Registering or indicating driving, working, idle, or waiting time only apparatus forming part of taximeters G07B13/00
• CPC Class Codes: G07C 5/0866 the electronic data carrier being a digital video recorder in combination with video camera
• CPC Class Codes: H04N 21/23406 involving management of server-side video buffer
• CPC Class Codes: H04N 21/41422 located in transportation means, e.g. personal vehicle arrangements specially adapted for transportation systems in broadcast systems H04H20/62
• CPC Class Codes: H04N 21/4223 Cameras H04N23/00 takes precedence
• CPC Class Codes: H04N 21/42692 for reading from or writing on a volatile storage medium, e.g. Random Access Memory [RAM]
• CPC Class Codes: H04N 21/4334 Recording operations recording of a television signal H04N5/76; arrangements for recording or accumulating broadcast information or broadcast-related information H04H60/27
• CPC Class Codes: H04N 21/44 Processing of video elementary streams, e.g. splicing a video clip retrieved from local storage with an incoming video stream or rendering scenes according to encoded video stream scene graphs
• CPC Class Codes: H04N 21/44004 involving video buffer management, e.g. video decoder buffer or video display buffer
• CPC Class Codes: H04N 21/440281 by altering the temporal resolution, e.g. by frame skipping television signal recording using magnetic recording on tape for reproducing at a rate different from the recording rate H04N5/783
• CPC Class Codes: H04N 21/4435 Memory management allocation of memory to service a request G06F9/5016; addressing or allocating within memory systems or architectures G06F12/02
• CPC Class Codes: H04N 5/77 between a recording apparatus and a television camera
• CPC Class Codes: H04N 7/181 for receiving images from a plurality of remote sources
• CPC Class Codes: H04N 7/183 for receiving images from a single remote source

Abstract

A vehicle event recorder is provided that includes a camera for capturing a video as discrete image frames, and that further includes a managed loop memory and a management system for generating a virtual ‘timeline dilation’ effect. To overcome size limits in the buffer memory of the video event recorder, the maximum time extension of a video series is increased by enabling a reduction in temporal resolution in exchange for an increase in the temporal extension. Memory cells are overwritten in an ‘interleaved’ fashion to produce a reduced frame rate for the recording of certain time periods connected to an event moment. In time periods furthest from the event moment, the resulting frame rate is minimized while in time periods closest to the event moment, the resulting frame rate is maximized.

Claims

1. A vehicle event recorder comprising:

a camera;

a managed loop buffer memory; and

an overwrite device,

the camera being operable for converting optical images into electronic signals suitable for recording in the managed loop buffer memory,

the managed loop buffer memory being a random access, rewritable, electronic storage medium of finite size suitable for storing data, including data arranged as discrete video frame data, and

the overwrite device being electronically coupled to the managed loop buffer memory and arranged to manage data overwrite operations,

whereby a first video frame older than a second video frame is saved in the managed loop buffer memory while the second video frame is overwritten.

2. The vehicle event recorder of claim 1, wherein the overwrite device being is arranged to overwrite data associated with a frame that is not the oldest frame in memory.

3. The vehicle event recorder of claim 1, wherein the overwrite device is arranged to overwrite data in an interleaved fashion, thereby causing an effective frame rate to be preserved by performing overwrite operations on alternate frames or frame sets.

4. The vehicle event recorder of claim 1, wherein the overwrite device further comprises an overwrite pointer arranged to point to a cell to be overwritten in a future overwrite action.

5. The vehicle event recorder of claim 1, wherein the overwrite device further comprises a timeline definition, which defines an expanded timeline and virtual frame rates and periods for those frame rates.

6. The vehicle event recorder of claim 5, wherein the timeline definition includes one timeline having three distinct periods and an event moment at the timeline midpoint, and wherein the frame rates associated with the periods at the timeline extremities are lower than the frame rate associated with the period including the event moment.

7. The vehicle event recorder of claim 5, wherein the timeline definition includes one timeline having five distinct periods and an event moment at the timeline midpoint, wherein the frame rates associated with the periods at the timeline extremities are the lowest, and wherein the frame rate associated with the period including the event moment is the highest.

8. The vehicle event recorder of claim 5, wherein the timeline definition includes an asymmetry, and wherein the frame rate is different for the periods after an event moment than the periods before an event moment.

9. The vehicle event recorder of claim 1, further comprising a high capacity long-term memory coupled to the managed loop buffer memory.

10. The vehicle event recorder of claim 9, further comprising an event trigger arranged to cause a transfer of data from the managed loop buffer memory, wherein the said high capacity long-term memory in an expanded timeline format.

11. The vehicle event recorder of claim 9, wherein the transfer of data step resets the managed loop memory into an initial state and a new timeline is initiated.

12. The vehicle event recorder of claim 9, wherein data in high capacity long-term memory is not overwritten in successive data transfer steps because the high capacity long-term memory includes capacity sufficient for a plurality of events.

13. A method of dilating a timeline of a video series in a vehicle event recorder, the video recorder comprising a managed loop buffered memory, the method comprising:

receiving electronic signal data associated with video frames from a video camera; and

overwriting previously written data with newly received data, whereby the previously written data is comprised of data belonging to a frame that is not the oldest frame in the memory.

14. The method of claim 13, wherein overwriting previously written data includes overwriting data in an interleaved fashion, and wherein successive frames are skipped to effect a reduced frame rate.

15. The method of claim 14, further comprising moving an overwrite pointer to a cell not a member of a timeline definition.

16. The method of claim 15, further comprising applying an overwrite operation to the cell associated with the pointer and further moving the overwrite pointer to another cell not part of the timeline definition.

17. A managed loop memory of a vehicle event recorder system comprising:

a coupling to a video camera output causing images from the video camera to be received at the managed loop memory;

a plurality of memory cells each being associated with a single video frame;

an overwrite pointer associated with one memory cell; and

a timeline definition directing the overwrite pointer to be associated with a cell that no longer remains a member of the timeline definition, thus subjecting the cell to an impending overwrite action.

18. The managed loop memory of claim 17, the timeline definition comprising two 12 second periods of 1 frame per second and one 48 second period of 4 frames per second, either of the 12 second periods falling before and after the 48 second period.