U.S. patent application number 11/369502 was filed with the patent office on 2007-09-20 for method for video/audio recording using unrestricted pre-event/post-event buffering with multiple bit and frame rates buffer files.
This patent application is currently assigned to Coban Research and Technologies, Inc.. Invention is credited to Hung C. Chang, Allan Chen, William Chichih Tai.
Application Number | 20070217761 11/369502 |
Document ID | / |
Family ID | 38517935 |
Filed Date | 2007-09-20 |
United States Patent
Application |
20070217761 |
Kind Code |
A1 |
Chen; Allan ; et
al. |
September 20, 2007 |
Method for video/audio recording using unrestricted
pre-event/post-event buffering with multiple bit and frame rates
buffer files
Abstract
Aspects of the present invention include method and apparatuses
that may be utilized to more efficiently use available storage
space for a digital video recording system in a law enforcement
vehicle and final "backend storage systems." In one embodiment of
the present invention, video and audio data is recorded in one or
more buffers when a triggering event is activated, while a digital
video recording device accounts for specified pre-event time, a
time period before a first triggering event has been activated, and
a post-event time, a time period after a second triggering event
has been activated. The system will tag the actual start and stop
points of events in one or more buffers based on a first and a
second triggering event and will then include the pre-event and
post-event data along with specified data. The system will then
extract the event from one or more buffer files and write the event
into final video files to be stored in a hard disk drive. By
recording the pre-event and post-event data in multiple buffer
files and extracting the final result from selected buffer files
based on the nature of the event type, the system ensures that
storage device is effectively used and, in this way, useful
information is recorded.
Inventors: |
Chen; Allan; (Sugar Land,
TX) ; Tai; William Chichih; (Sugar Land, TX) ;
Chang; Hung C.; (Sugar Land, TX) |
Correspondence
Address: |
PATTERSON & SHERIDAN, L.L.P.
3040 POST OAK BOULEVARD
SUITE 1500
HOUSTON
TX
77056
US
|
Assignee: |
Coban Research and Technologies,
Inc.
|
Family ID: |
38517935 |
Appl. No.: |
11/369502 |
Filed: |
March 7, 2006 |
Current U.S.
Class: |
386/228 ;
386/E5.072 |
Current CPC
Class: |
H04N 9/79 20130101; H04N
9/7921 20130101; G11B 2020/1062 20130101; H04N 5/772 20130101 |
Class at
Publication: |
386/086 |
International
Class: |
H04N 5/95 20060101
H04N005/95 |
Claims
1. A vehicle-mounted digital video recording device for capturing
video data during an event comprising: a storage medium; a buffer;
and a processing device configured to record video data for a first
pre-determined amount of time into the buffer prior to receiving a
signal indicating a start of the event, continue to record video
data of the event into the buffer after receiving the signal
indicating the start of the event, continue to record video data
for a second pre-determined amount of time after receiving a signal
indicating an end of the event, and extract the video data from the
buffer and store it in a storage medium.
2. The digital video recording device of claim 1, wherein the
digital video recording device is configured to set a value for the
duration of the first pre-determined amount of time based on a user
input.
3. The digital video recording device of claim 1, wherein the
digital video recording device is configured to set a value for the
duration of the second pre-determined amount of time based on a
user input.
4. The digital video recording device of claim 1, wherein the video
data is stored simultaneously in a plurality of buffer files.
5. The digital video recording device of claim 4, wherein the
plurality of buffer files store video data of the same event at
different video resolutions.
6. The digital video recording device of claim 1, wherein the
digital video recording device tags a first point in the buffer
indicating receipt of the signal indicating the start of the
event.
7. The digital video recording device of claim 6, wherein the
digital video recording device is configured to tag a second point
in the buffer indicating the first pre-determined amount of time
before the first point.
8. The digital video recording device of claim 1, wherein digital
video recording device tags a third point in the buffer indicating
receipt of the signal indicating the end of the event.
9. The digital video recording device of claim 8, wherein the
digital video recording device is configured to tag a fourth point
in the buffer indicating the second pre-determined amount of time
after the third point in the buffer.
10. The digital video recording device of claim 6, wherein the
digital video recording device is configured to tag the first point
in response to a manual pressing of a record button.
11. The digital video recording device of claim 8, wherein the
digital video recording device is configured to tag the third point
in response to a manual pressing of a stop button.
12. The digital video recording device of claim 1, further
comprising: recording audio data that is associated with the video
data in the same buffer simultaneously, wherein the recording of
the audio data may be deactivated manually by pressing an audio
stop button.
13. The digital video recording device of claim 1, further
comprising: recording audio data that is associated with the video
data in the same buffer simultaneously, wherein the digital video
recording device is pre-programmed to activate the recording.
14. The digital video recording device of claim 1, wherein the
digital video recording device is configured to resume extracting
the video data after the digital video recording device is turned
on again at some point in the future, if the digital video
recording device was turned off while extracting the video
data.
15. A method for recording video data with a vehicle-mounted
digital video capturing device corresponding to an event
comprising: recording pre-event video data into a buffer prior to
receiving a signal indicating a start of the event; recording event
video data into the buffer after receiving a signal indicating the
start of the event; recording post-event data into the buffer after
receiving a signal indicating an end of the event; extracting the
pre-event video data, the event video data and the post-event video
data from the buffer after recording a pre-determined amount of
video data of the post-event video data into the buffer; and
storing the pre-event video data, the event video data and the
post-event video data in a storage medium.
16. The method of claim 15, wherein the signal indicating the start
of the event and the signal indicating the end of the event are
generated by a triggering device in a vehicle.
17. The method of claim 15, wherein the signal indicating the start
of the event and the signal indicating the end of the event are
generated by a pressing of a button in a vehicle.
18. The method of claim 15, wherein the vehicle-mounted digital
video capturing device is adapted to set time periods for the
pre-event video data and post-event video data based on user
selections.
19. A method for recording video data corresponding to an event,
comprising: monitoring for a signal indicating a start of an event,
recording video data of the event after detecting the signal
indicating the start of the event, wherein the video data of the
event is stored at different resolutions in at least two separate
buffers; selecting the video data stored in one of the buffers
after detecting a signal indicating an end of the event; and
storing the selected video data in a storage medium.
20. The method of claim 19, wherein the at least two separate
buffers comprises a first buffer adapted to record video data at a
high resolution and a second buffer adapted to record video data at
a low resolution.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates generally to digital video
recording devices, and more particularly, to methods and
apparatuses for digital video recording using pre-event/post-event
buffering.
[0003] 2. Description of the Related Art
[0004] Digital technology has allowed law enforcement agencies
around the world to make audio and video recording an essential
tool for protection against false and malicious claims, for
prosecuting defendants, and for training. Digital video recording
provides obvious benefits over analog (VCR tape-based) video
recording systems in quality, storage and a variety of options,
such as the ability to search and locate a particular scene within
a recording segment.
[0005] As shown in FIG. 1, generally, a digital video recording
device 106, in a law enforcement vehicle 1 10, is in communication
with a video camera 120, a general purpose computer 107, which may
be separate as shown or integrated with the digital video recording
device 106 as one unit, an audio input device (not shown), and a
storage medium, for example, a hard disk drive 105. Digital video
recording device 106 may interface with triggering devices (e.g.,
siren, light bar, air bag, vibration sensor) and/or switches for
triggering permanent recording of the video and audio data to the
hard disk drive 105. The video camera 120 is generally mounted to
capture video data out the front window of the vehicle 110. An
audio input device (not shown) may, in any combination, be mounted
in the vehicle 110, worn by an officer, and/or provided as an
output of the vehicle's two-way radio.
[0006] Generally, audio and video data is transferred to a storage
medium, such as hard disk drive 105. In operation, a trigger event
activates the digital video recording device 106 and in this way,
the video and audio data is captured and then written to a memory
device, such as hard disk drive 105. The recorded video data may
then be archived, for example, by transferring (uploading) the data
to a network for archiving or removing the hard disk drive to which
it is recorded. A common problem with such systems is balancing the
availability of a finite amount of physical space for storage of
captured video and audio in a hard disk drive of a moving vehicle
with potentially large amounts of information which may need to be
recorded over long periods of time.
[0007] One known approach for addressing this problem involves only
activating the digital video recorder in response to specific
triggering events, such as an opening of a door, turning on a siren
and/or lights, or removing a gun from a rack. By only recording
when particular events occur, such arrangements can reduce the
amount of video information to be recorded.
[0008] However, such techniques are cumbersome and costly in many
ways. Often, when an event has been recorded, it is found to be of
no use to the enforcement agency after it has been stored in the
physical space of a law enforcement vehicle. In addition, these
required triggering events tend to ensure that the period of time
after the ending of the event will not be recorded. Unfortunately,
this subsequent period of time is often found to be of great
interest when later analyzing the recorded information. Further,
this method does not give a law enforcement officer an ability to
choose and record only pertinent data needed to be saved to a hard
disk drive after the triggering event is activated and disregard
data that is found to be of no value.
[0009] Therefore, a need exists for an improved method and an
apparatus for digital video recording.
SUMMARY OF THE INVENTION
[0010] One embodiment provides a vehicle-mounted digital video
recording device for capturing video data during an event
comprising a storage medium, a buffer, and a processing device
configured to record video data for a first pre-determined amount
of time into the buffer prior to receiving a signal indicating a
start of the event, continue to record video data of the event into
the buffer after receiving the signal indicating the start of the
event, continue to record video data for a second pre-determined
amount of time after receiving a signal indicating an end of the
event, and extract the video data from the buffer and store it in a
storage medium.
[0011] Another embodiment provides a method for recording video
data with a vehicle-mounted digital video capturing device
corresponding to an event comprising recording pre-event video data
into a buffer prior to receiving a signal indicating a start of the
event, recording event video data into the buffer after receiving a
signal indicating the start of the event, recording post-event data
into the buffer after receiving a signal indicating an end of the
event, extracting the pre-event video data, the event video data
and the post-event video data from the buffer after recording a
pre-determined amount video data of the post-event video data into
the buffer, and storing the pre-event video data, the event video
data and the post-event video data in a storage medium.
[0012] Another embodiment provides a method for recording video
data corresponding to an event, comprising monitoring for a signal
indicating a start of an event, recording video data of the event
after detecting the signal indicating a start of the event, wherein
the video data of the event is stored at different resolutions in
at least two separate buffers, selecting the video data stored in
one of the buffers after detecting a signal indicating an end of
the event, and storing the selected video data in a storage
medium.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] So that the manner in which the above recited features of
the present invention can be understood in detail, a more
particular description of the invention, briefly summarized above,
may be had by reference to embodiments, some of which are
illustrated in the appended drawings. It is to be noted, however,
that the appended drawings illustrate only typical embodiments of
this invention and are therefore not to be considered limiting of
its scope, for the invention may admit to other equally effective
embodiments.
[0014] FIGS. 1 illustrates an exemplary layout of a law enforcement
vehicle, using a digital video recording device;
[0015] FIG. 2 illustrates how a buffer file may be used, according
to an embodiment of the present invention;
[0016] FIG. 3 illustrates a flow diagram of a processing method
according to an embodiment of the present invention;
[0017] FIG. 4 illustrates how multiple buffer files may be used,
according to an embodiment of the present invention; and
[0018] FIG. 5 illustrates a flow diagram of a processing method
according to another embodiment of the present invention.
DETAILED DESCRIPTION
[0019] Embodiments of the present invention provide methods and
apparatuses that may be utilized to more efficiently use available
storage space for a digital video recording system in a law
enforcement vehicle. For example, video and audio data is recorded
in one or more buffers when a triggering event is activated, while
a digital video recording device accounts for specified pre-event
time, a time period before a first triggering event has been
activated, and a post-event time, a time period after a second
triggering event has been activated. The system will tag the actual
start and stop points of events in one or more buffers based on a
first and a second triggering event and will then include the
pre-event and post-event data along with specified data. The system
will then extract the event from one or more buffer files and write
the event into final video files to be stored in a hard disk drive.
By recording the pre-event and post-event data in buffer files, the
system ensures that storage device is effectively used and, in this
way, useful information is recorded.
[0020] While the following description of the system is described
with reference to a law enforcement vehicle, the same techniques
may be applied to other applications where surveillance and video
data monitoring may be useful, such as military and security
systems.
[0021] FIG. 2 illustrates how a buffer file may be used for
recording video data according to an embodiment of the present
invention. As shown in FIG. 2, and as will be described herein,
video data may be associated with different time periods: a
pre-event time period, an event time period, and a post-event time
period. The digital video recording device may capture video data
for these time periods in a plurality of buffer files during its
operation. In one embodiment of the present invention, buffer file
200 may be used for storing video data when a recording function is
triggered or when the digital video recording unit is turned
on.
[0022] In the illustrated example, buffer file 200 includes a first
buffer segment 210 and a second buffer segment 220, corresponding
to separate recorded events. The first buffer segment 210 includes
a buffer start point T.sub.A; a first event trigger point (start
trigger point) T.sub.B; a first pre-event point T.sub.C; a second
event trigger point (stop trigger point) T.sub.D and a first
post-event point T.sub.E. The first buffer segment 210 may include
a pre-event length of video data (e.g., L.sub.2) after a time
period, for example, L.sub.1, an event length of video data (e.g.,
L.sub.3) and a post-event length of video data (e.g., L.sub.4).
[0023] The embodiment illustrated in FIG. 2 may be best understood
with simultaneous reference to FIG. 3, which illustrates operations
300 according to an implementation of the present invention. At
step 310, the digital video recording device may start capturing
video as soon as it is turned on. Since the system is constantly
recording, it will capture the event leading up to a triggering
event. In this way, the system ensures that useful information
(activities) that occur prior to the triggering event, and which
may be of value at a later time, is recorded. In other words, the
system will not miss any pre-event activities.
[0024] At step 320, the digital video recording system monitors for
a triggering event. In one embodiment of the present invention, for
example, a first triggering event may be the manual pressing of a
record button, or sending of a signal to the digital video
recording device from a mechanism, such as a wireless microphone,
or the removal of a gun from a rack. At step 330, in response to
detecting a triggering event, the digital video recording device
may tag the starting point for the event at point T.sub.B. The
digital video recording device, at step 335, may also account for a
specified pre-event length of video data, for example, L.sub.2, and
may tag the start of the pre-event period in the buffer file at an
earlier point T.sub.C.
[0025] The digital video recording device continues to record the
event while monitoring, at step 340, for a stop triggering event.
At step 345, after detecting a stop triggering event, the digital
video recording device may tag the stopping point for the event at
T.sub.D. The digital video recording device, at step 350, may
continue to record for a post-event time period to ensure that
activities after the event that may be useful are captured. In
other words, the system may account for a specified post-event
length of video data, for example, L.sub.4, and may tag the end of
the post-event period in the buffer file at a later point
T.sub.E.
[0026] In this way, the digital video recording device ensures that
pre-event and post-event video data are also recorded, in addition
to the target video data. This feature of the digital video
recording device ensures the capturing of useful evidence that
otherwise would be lost.
[0027] At step 365, the digital video recording device may extract
the event from the buffer file and transfer the event to a final
video file in a storage medium, for example, a hard disk drive,
located in a law enforcement vehicle. In one embodiment of the
present invention, if the digital video recording device is unable
to finish extracting all of the video data before it is turned off,
the digital video recording device will resume the extraction
process once it is turned on at some point in the future. In one
embodiment of the present invention, the digital video recording
device may delay the extraction process until the size of the
buffer file reaches a predefined threshold value (e.g., a value
selected by a law enforcement agency or by a user).
[0028] In some embodiments of the present invention, the digital
video recording device may provide a user the ability to set
specified durations for pre-event and post-event lengths of video
data. For example, a graphical user interface (GUI) may be employed
to allow users to either select values of fixed amounts from a
pull-down menu or input values of their choice for the pre-event
and post-event time periods. In some embodiments of the present
invention, the pre-event and post-event time periods may range
anywhere from several seconds to several minutes. For example, in
one embodiment of the present invention, the digital video
recording device may optionally be set to have a pre-event length
of video data that is substantially close to 60 seconds and a
post-event length of video that is substantially close to 120
seconds.
[0029] In one embodiment of the present invention, the digital
video recording device is capable of recording audio data that is
associated with the video data in the same buffer file
simultaneously. In one embodiment of the present invention, the
digital video recording device may account for the audio data that
is associated with the pre-event and the post-event video data and
record pre-event and post-event audio data in a buffer file. In one
embodiment of the present invention, the storing of the audio data
may be deactivated manually by pressing an audio stop button (not
shown). For some embodiments of the present invention, the storing
of the audio data may be pre-programmed to be activated or
deactivated by the law enforcement agency based on its
policies.
[0030] In any case, after a first event has been recorded in a
buffer file, the digital video recording device may record other
events that occur subsequent to the first event. As illustrated in
FIG. 2, buffer 200 may include a second buffer segment 220, which
follows the first segment 210. Similar to the first segment,
segment 220 includes a buffer start point T.sub.A; a first event
trigger point (start trigger point) T.sub.F; a first pre-event
point T.sub.G; a second event trigger point (stop trigger point)
T.sub.H and a first post-event ending point T.sub.I. The second
buffer segment 220 may be separated from the first buffer segment
210 by a time period, for example, L.sub.5, and it may include a
pre-event length of video data (e.g., L.sub.6), an event length of
video data (e.g., L.sub.7) and a post-event length of video data
(e.g., L.sub.8). In this embodiment, the digital video recording
device is capable of recording a second event after recording the
first event. Similar to recording techniques described above with
reference to segment 210, the digital video recording device
ensures that pre-event and post-event video data for a second
target video data in segment 220 are also recorded. This feature of
the digital video recording device ensures the capturing of useful
evidence that otherwise would be lost.
[0031] For some embodiments of the present invention, a second
event may start during the post-event recording of the first event.
In other words, the digital video recording device is capable of
tracking multiple events that may have overlapping time
periods.
[0032] In one embodiment of the present invention, the digital
video recording device may delay the extraction process until a
predefined number of events have been recorded in a buffer file. In
another embodiment of the present invention, the digital video
recording device may delay the extraction process until the size of
the buffer file reaches a predefined threshold (e.g., a value
selected a law enforcement agency or a user). In yet another
embodiment of the present invention, a user, for example, an
officer, may choose to adjust the frequency of the extraction
process based on the length of the captured target video segments.
In one embodiment of the present invention, if the digital video
recording device is unable to finish extracting all of the video
events before it is turned off, the digital video recording device
will resume the extraction process once it is turned on at some
time in the future. In another embodiment of the present invention,
the digital video recording device may extract each event from the
buffer file and transfer the event to a final video file in a
storage medium, one after another.
Multiple Resolution Recording
[0033] In order to achieve storage usage efficiency of the stored
video data, it is advantageous to optionally choose to record
certain video events in high resolution format, and other video
events in a lower resolution format, since higher resolution video
data requires more storage space. Although it is possible to store
all events in high resolution and then compress the data at a later
time to accommodate storage efficiency, this may alter the original
video data and then it may not be acceptable as admissible court
evidence. Further, in some cases, certain portions of the data may
be lost during the compression process. Therefore, it is
advantageous to have the option to choose between high resolution
video data recording and low resolution video data recording.
[0034] In one embodiment of the present invention, the digital
video recording device may record a single video event in a
plurality of buffer files using different resolutions (e.g.,
multiple frame or bit rates) simultaneously. Then at the end of the
event, the final video data may be extracted from one of the buffer
files (e.g., low resolution buffer file or a high resolution buffer
file) based on the event type. In this way, video recordings that
may be used for evidentiary purposes may be extracted from a high
resolution buffer, and other types of video recordings may be
extracted from a low resolution buffer, in order to save storage
space and reduce file transfer time.
[0035] In one embodiment of the present invention, a single video
event may be recorded in a plurality of buffer files using
different resolutions (e.g., multiple frame or bit rates)
simultaneously. As illustrated in FIG. 4, two buffers files are
used for recording video data according to an embodiment of the
present invention. The embodiment illustrated in FIG. 4 may be best
understood with simultaneous reference to FIG. 5, which illustrates
operations 500 according to an implementation of the present
invention.
[0036] Operations 500 begin at step 510, where the digital video
recording device monitors for a start trigger event. At step 520,
once a start trigger event is detected, the same video event is
stored in a plurality of buffer files at different resolutions. For
example, as shown in FIG. 4, segment 460 of a first buffer file 450
and segment 480 of a second buffer file 470 are both used to store
a first video event, but at different resolutions. In one
embodiment of the present invention, buffer file 450 may use a high
resolution format, for example, a Moving Pictures Experts Group
(MPEG)-2, capable of recording video data at a 5 Mbps bit rate, and
buffer 470 may use a low resolution format, for example, MPEG-4,
capable of recording video data at a 400 Kpbs bit rate. The same
event is recorded simultaneously in both buffers 450 and 470.
[0037] After a stop trigger event is detected at step 525, the
operator of the digital video recording device, at step 530, can
choose between different resolutions of the same event recorded at
different frame or bit rates by selecting a buffer file from buffer
files 450 or 470. Depending on the type of event that is being
recorded, a user may decide to extract an event recorded in high
resolution format and similarly, a user may decide to extract
another event recorded in low resolution format from buffer files
450 or 470. Since higher resolution format data will consume more
storage space, a user may decide to extract only those events that
are of greater significance from the high resolution buffer, for
example, buffer 450, and extract events from the low resolution
buffer, for example, buffer 470 that are of lesser
significance.
[0038] For some embodiments, at the end or beginning of recording,
a predefined event category may be assigned to the video event. In
law enforcement, different events may be associated with a high or
a low resolution buffer. In one embodiment of the present
invention, the digital video recording device may determine which
buffer to use based on user selection. In another embodiment of the
present invention, the resolution selection may be automated based
on law enforcement agency standards. For example, video recordings
that may be used for evidentiary purposes, such as recording of a
potential driving while intoxicated (DWI) offense, may be extracted
from a high resolution buffer automatically. On the other hand, a
routine stop for license plate expiration may automatically use a
low resolution buffer in order to save storage space.
[0039] In one embodiment of the present invention, the digital
video recording device is capable of recording audio data that is
associated with the video data in a plurality of buffer files
simultaneously. In one embodiment of the present invention, the
digital video recording device may account for the audio data that
is associated with the pre-event and the post-event video data and
record pre-event and post-event audio data in a plurality of buffer
files. In one embodiment of the present invention, the recording of
the audio data may be deactivated manually by pressing an audio
record button (not shown). For some embodiments of the present
invention, the storing of the audio data may be pre-programmed to
be activated or deactivated by the law enforcement agency based on
its policies.
[0040] Although the embodiments disclosed above, which incorporate
the teachings of the present invention, have been shown and
described in detail herein, those skilled in the art can readily
devise other varied embodiments which still incorporate the
teachings and do not depart from the spirit of the invention.
* * * * *