 |
Claims  |
|
|
What is claimed is:
1. A system for recording and playing back to users a plurality of
different aspects including visual, audible, graphic, or textual
presentations of a multimedia event, each captured by a distinct one of a
plurality of recording sources, to facilitate the indexing capability of
users, wherein each of said captured aspects forms a distinct original
continuous media temporal record of said multimedia event, said system
comprising:
a preprocessor for processing each said original record, said preprocessor
including
a digitizer for transforming each said original record into digitized
blocks, and
means for generating derivative records, said means comprising a time stamp
processor for time stamping each of said digitized blocks of each said
original record with the relative time for said multimedia event and a
derivative continuous temporal record generator for processing said
original records to generate derivative records which contain arrangements
of information in said original records to assist users in searching
through said multimedia event;
a delivery processor for delivering to said users both said derivative
records processed at said preprocessor and each said original record and
for adjusting delivery of said original records of said multimedia event
based on interactive commands received from users;
user control units for receiving said original and derivative records of
said multimedia event from said delivery processors and transmitting to
said delivery processor users' requests for said multimedia event and
users' interactive commands for playing back said multimedia event,
wherein each of said user control units includes a user local clock for
tracking a relative time for said requested multimedia event and each said
user control presents each said block of each said original and derivative
record when said relative time of each said block matches said relative
time at said user local clock; and
output devices for displaying derivative records to enable identification
of the occurrence of events in one or more of said original records.
2. The recording and play back system of claim 1, wherein said preprocessor
further comprises a compressor, connected to said time stamp processor,
for compressing said records of said multimedia event, said derivative
record generator being connected to said compressor.
3. The recording and playback system of claim 1, wherein said preprocessor
further comprises an input interface, connected to the recording sources,
said input interface including source receivers for receiving said
original records from the recording sources.
4. The recording and play back system of claim 1, wherein said preprocessor
further comprises a store for holding a record mapping table which
includes instructions for digitizing, compressing, and processing said
original records of said multimedia event.
5. The recording and play back system of claim 3, wherein said preprocessor
further comprises a local clock, connected to said time stamp processor,
for keeping time for said multimedia event.
6. The recording and play back system of claim 1, wherein said derivative
record generator of said preprocessor comprises a character recognition
device, for generating said derivative records by identifying and
extracting strings of characters from said original records of said
multimedia event, said derivative records being utilized by users to
locate points of interest in said multimedia event based on said
identified strings of characters.
7. The recording and play back system of claim 6, wherein said derivative
record generator of said preprocessor also comprises a speaker
identification device for generating further derivative records by
detecting and extracting voice patterns from said original records, said
further derivative records being utilized by users to locate points of
interest in said multimedia event based on changes in voice patterns.
8. The recording and play back system of claim 7 wherein said derivative
record generator of said preprocessor also includes a resolution device
for generating additional derivative records by changing the resolution of
said original records.
9. The recording and play back system of claim 4, wherein said derivative
record generator of said preprocessor comprises a record distributor for
receiving said original records from said compressor and distributing said
original records among devices of said derivative record generator based
upon said processing instructions at said record mapping table.
10. The recording and play back system of claim 1, further comprising an
event mass storage, connected to said preprocessor, for storing said
multimedia event from said preprocessor, and wherein said delivery
processor further comprises a delivery controller, which, on receiving a
request from a user for said multimedia event, causes said original and
said derivative records and said record mapping table of said multimedia
event to be retrieved from said event mass storage and stored at said
delivery processor and identifies records of said multimedia event to be
delivered to said requesting user.
11. The recording and play back system of claim 10, wherein said delivery
processor, on receiving an interactive command from said user control unit
of said requesting user for one of said derivative records, causes said
event processor to deliver blocks of said one derivative record to said
user control unit of said requesting user, said blocks of said derivative
record being synchronized in time with respect to other records being
delivered to said user control unit of said requesting user.
12. A system for recording and playing back to users a plurality of
different aspects including visual, audible, graphic, and textual
presentations of a multimedia event to facilitate indexing by a user, said
system comprising:
means for receiving from multiple input devices different original
continuous media temporal records, each comprising a different
representation of the multimedia event;
means for coding said original records in digital blocks;
means for stamping each of said blocks with the same relative time for the
multimedia event;
means for storing a record mapping table;
means responsive to said storing means for compressing information in said
original records dependent upon the type of information;
means responsive to said compressing means for converting said information
in said original records including said relative time into a plurality of
derivative continuous temporal records;
means for displaying said derivative records to enable identification of
the occurrence of an event in one or more of said original records; and
means responsive to users' requests for receiving and presenting one or
more of said original records.
13. The system in accordance with claim 12, further comprising
means for generating a stacked representation of one of said derivative
records.
14. The system in accordance with claim 13, wherein said means responsive
to said users' requests selects one of said original and derivative
records, or a stacked representation of one of said derivative records for
retrieval and display.
15. A method for recording and playing back a plurality of different
aspects including visual, audible, graphic, or textual presentations of a
multimedia event to facilitate indexing by a user comprising the steps of:
receiving from multiple input devices different original continuous
temporal records, each comprising a different representation of the
multimedia event,
coding said original records into digital blocks,
time stamping each of said blocks with the same relative time for said
multimedia event,
converting information in said original records including the relative time
into a plurality of derivative continuous temporal records,
retrieving and displaying said derivative records responsive to a user's
request as an index to locate a particular portion of one of said original
records, and
responsive to the display of said derivative records to enable the display
of said original records.
16. A method in accordance with claim 15, further comprising the step of
compressing information in said original records in accordance with the
type of information in said original records.
17. A method in accordance with claim 15, further comprising the step of
generating a stacked representation of one of said original and derivative
records.
18. A method in accordance with claim 17, wherein said retrieving and
display step further comprises the step of selecting one of said
derivative records or a stacked representation of one of said derivative
records.
19. A system for recording and playing back a plurality of different
aspects including visual, audible, graphic, or textual presentations of a
multimedia event, said system comprising:
a preprocessor including
input interface means for receiving different original continuous media
temporal records each comprising a different representation of the
multimedia event,
means for digitizing and time stamping blocks of information for each said
original record with the same relative time,
means for compressing said information in said original records in
accordance with the type of information in said records, and
means for converting said information in said original records into
different forms in derivative temporal records including the stamped
relative times;
a mass storage element for receiving outputs from said preprocessor;
a delivery processor including
an event store for receiving outputs from said mass storage element,
an event processor for generating stacked representations of said
derivative records in said event store, and
delivery control means responsive to inputs from a user for selectively
causing said information of said original and said derivative records and
stacked representations of said information of said derivative records to
be transmitted for display; and
display means for displaying said derivative records as an index to locate
a particular occurrence on one or more of said original records.
20. The system in accordance with claim 19, further comprising a user
control unit for receiving inputs from the user and for receiving from
said delivery processor the information to be displayed, said control unit
including
network interface means for receiving said information to be displayed,
a demultiplexer connected to said network interface means,
a decompressor connected to said demultiplexer, and
means responsive to said decompressor for presenting said information to be
displayed to the user.
21. The system in accordance with claim 20,
wherein said preprocessor further comprises means for storing a record
mapping table, said means for compressing being responsive to said record
mapping table, and
wherein said user control unit further comprises means for storing said
record mapping table, said decompressor being responsive to said record
mapping table.
22. The system in accordance with claim 20,
wherein said means for digitizing and time stamping stamps blocks of
information with a relative time for the multimedia event, and
wherein said user control unit includes clock means for indicating said
relative time and said means for presenting said information compares the
relative time from said clock means to said relative time on said blocks
of information from said decompressor. |
|
 |
|
 |
Claims |
|
|
|
Description |
|
|
RELATED APPLICATIONS
U.S. patent application Ser. No. 08/274,503, entitled Apparatus and Method
for Preprocessing Multimedia Presentations and U.S. patent application
Ser. No. 08/274,502, entitled System and Method for Preprocessing and
Delivering Multimedia Presentations, both filed on Jul. 13, 1994, for the
inventors G. C. Cruz, R. D. Hill, T. H. Judd, D. H. New, and J. Rosenberg,
and assigned to the assignee hereof, contain subject matter related to
that of the present application.
FIELD OF THE INVENTION
This invention relates to a system and method for recording and playing
back multimedia events.
BACKGROUND OF THE INVENTION
A shared communications experience is an event at which groups of
communicants engage in the exchange of information and ideas. Such events
include business and technical presentations, training sessions, lectures,
and meetings. A shared communications experience might also include a
teleconferencing session between participants located remotely from one
another. Where the event entails the exchange of different forms (e.g.,
video, text, and audio), the event is commonly characterized as a
multimedia event. The exchange of information may be assisted by both
non-electronic devices (e.g., view graphs, white boards, and notepads) and
electronic devices (e.g., video, computers, and electronic white boards).
FIG. 1 depicts an example of a multimedia event and electronic and
non-electronic devices that might be employed to facilitate communication.
At the training session, there is a lecturer 110, who presents information
to trainees 111-114 seated in the training room 100. To facilitate
presentation of the information to the trainees, the lecturer utilizes a
view graph machine 120, which projects an image on to a projection screen
125. The lecturer also utilizes an electronic white board 127 for drawing
handwritten notes and diagrams.
Shared communications experiences, such as that shown in FIG. 1, are often
recorded to allow persons unable to attend the event to benefit from the
exchange of information and ideas. The recording also permits attendees to
review the event and clarify details that were missed during the live
event. A technique for recording such events may include using written
notes, such as those that might be taken by one of the trainees 111-114 at
the training session. Written notes result in a subjective interpretation
of the event that may lack important visual information, such as the
speaker's body language and trainees' non-verbal responses to lecture
materials as well as audible information such as the speaker's tone of
voice. Another drawback is that the written notes are also a subjective
interpretation of the event by the scrivener.
Another technique involves recording the audio of the event on audio
cassettes. Pure audio recordings can be a more accurate and complete
record of the experience than written notes, but are difficult to browse
or search. Therefore, if a user of the recording were only interested in
hearing a portion of the event where the lecturer 110 answered a question
asked by trainee 111, the listener must randomly advance and reverse in
the audio recording until stumbling upon the desired segment. As with
written notes, visual cues from the event are lost.
A commonly preferred technique for recording events is using a video
camcorder operated by human operator. A video recording provides the most
accurate representation of the event, but often does not provide adequate
coverage of the whole experience because of the limited field of view of
conventional video camcorders. Furthermore, the view of the event captured
in the video recording has been subjectively selected by the human
operator, and this view may not coincide with the view of the event
desired by a user of the video recording. For example, the camera operator
may focus on the view graphs projected onto the projection screen 125
while the lecturer 110 is emphasizing a point and miss the gestures of the
lecturer 110 used to illustrate the point. Consequently, users of the
recording will never see these gestures. Optimally, both the view graphs
and the lecturer should be captured such that users of the recording have
the option to choose which view should be presented. But, under
conventional single camera recording systems, users of the video recording
are limited to the view subjectively selected by the camera operator.
Alternatively, the video recording can be generated using a more
sophisticated technique employing multiple cameras and other equipment as
described in Braun et al U.S. Pat. No. 5,187,571, Feb. 16, 1993, which
cameras and equipment facilitate the capturing and contiguous merging of
multiple views of an event to form an aggregate field view. Under this
approach, cameras 130, 140, and 150 could be used to capture Regions A, B,
and C, respectively, of the training session as shown in FIG. 1. This
approach provides a more faithful reproduction of the entire event than
any approach previously mentioned, but production of the recording can be
cost-prohibitive and the quality of the recording is limited by the
resolution of the medium on which the recording is stored. By capturing a
full view of the event, the resolution of any aspect of the event is
significantly diminished. For example, by recording a full view of the
lecture session comprising the fields of view of cameras 130, 140, and
150, the notation on the white board 127 and the text on the view graphs
projected on screen 125 may be illegible. This is because video is a
relatively poor medium for recording certain information, such as text
written on a white board and in view graphs projected on a screen.
Even with sophisticated recording techniques, the video recording may be of
little benefit to a user in browsing, reviewing, or analyzing the event.
Many of the limitations are a result of the analog medium used for storing
the recording. Analog recordings are used because of the low costs and
wide availability of equipment and storage media such as Video Home System
(VHS) video tapes. Technology such as the Society of Motion Picture and
Television Engineers (SMPTE) time code, which facilitates indexing video
tape, computer-controlled videodisc players, and video cassette recorders
(VCRs) may overcome some of the limitations, but others remain. In
particular, due to its lack of structure and slow access, analog video
tape is difficult to browse to identify quickly points of interest.
Similar to the audio recording, locating a point of interest requires that
the user randomly advance and reverse in the video recording until
stumbling upon the point of interest. Furthermore, once the point of
interest has been located, the viewer has limited flexibility, if any, to
control the resolution of an aspect of the recording or to disable an
unwanted aspect of the recording. For example, under conventional
approaches, a viewer would not have the flexibility of increasing the
resolution of the audio portion of a recording to increase the audible
clarity of a question from trainee 111 to the lecturer 110, or totally
disabling the view from camera 140 of Region B.
Another consideration when selecting a mechanism for recording an event is
the method of delivering the recorded event to the user. One delivery
alternative is to transmit the recording from a service provider to a user
over a network in real time. However, a limitation of conventional video
recordings is that such recordings are bandwidth intensive and often
exceed the bandwidth capabilities of the network and the user's
facilities, thereby precluding this alternative as a method of delivering
recordings to users.
In view of these drawbacks and shortcomings of conventional approaches to
recording shared communication experiences including multimedia events,
our objective is a system and method for recording and playing back an
event such that a user of the recording can control the aspects of the
event being presented. A further objective is to facilitate browsing and
searching through a recording to locate a point of interest in the
recorded event. Another objective is to record events such that the
aspects of the event delivered to the user can be adapted to meet
constraints of the network, such as bandwidth limitations, and the user's
equipment.
SUMMARY OF THE INVENTION
Aspects of our invention are a system and method for recording and playing
back multimedia events, such as business and technical presentations,
training sessions, lectures, and meetings. Our inventive system includes
recording sources, a preprocessor, event mass storage, a delivery
processor, a distribution network, and user control units. The recording
sources are devices, such as audio recorders and video camcorders, each of
which captures an aspect of the multimedia event, which aspect is referred
to herein as a multimedia track or a continuous media temporal record. The
recording source transmits the track or record to the preprocessor where
each track is received, coded into digital blocks, if necessary, and time
stamped. Digitized blocks of tracks that are simultaneously received at
the preprocessor are assigned the same relative time and therefore
synchronized in time. At the preprocessor, some tracks of the multimedia
event are also compressed to reduce the bandwidth required for
transmitting a multimedia event to a user. The digitization and
compression techniques employed for each track are dictated by entries in
a track or record mapping table, which entries are based on the type of
information carried by the track. For example, tracks carrying
predominately textual information may be digitized and compressed
differently than tracks carrying full motion video. In addition, the
original records or tracks of the multimedia event may be preprocessed to
generate other representations of the multimedia event, known derivative
continuous temporal records or tracks, which further assist users in
searching through the multimedia event.
Our inventive system also includes an event mass storage where recordings
of multiple multimedia events are stored for delivery to requesting users.
At the event mass storage, the tracks of a multimedia event, which tracks
each represents different aspects of the event, are maintained as separate
and distinct tracks. Another component of our inventive system is the
delivery processor which services requests for multimedia events from
multiple users, retrieves requested events from the event mass storage,
and delivers events to requesting users according to the users'
interactive commands. The delivery processor is connected via the
distribution network to multiple user control units, where requests and
interactive commands from the user are received and multimedia events from
the delivery processor are received for presentation to the user. The
delivery processor may also identify the aspects of the event to be
delivered to a user control unit based upon the bandwidth limitations of
the distribution network and the capabilities of the user equipment. The
delivery processor also generates stacked representations of the tracks of
the multimedia event, which representations provide visual cues to assist
the user in conducting intelligent searches through the multimedia event
and in locating points of interest.
The user control unit is connected to user output devices, which convert
the tracks of the multimedia event received from the delivery processor
into a form suitable for the user. The user control unit is also connected
to user input devices, where users input requests and interactive
commands.
Our inventive method for recording and playing back multimedia events
entails capturing various aspects of a multimedia event, such as a
training session, using multiple recording sources. The tracks or records
generated by the recording sources are received at the preprocessor, where
the tracks are coded into digitized blocks, time stamped, compressed,
preprocessed, and transferred to and stored at the event mass storage. On
a request for a multimedia event being received from a user, the delivery
processor responds by retrieving the requested multimedia event from mass
storage and delivering the tracks of the event, which tracks represent
aspects of the event, to the user control unit. If only certain aspects of
the multimedia event were requested by the user or if the distribution
network or user output devices are not capable of supporting all aspects
of the event, the delivery processor will cause those aspects that are
requested and capable of being received to be delivered. The tracks are
then presented by the user control unit at the user output devices. By
interacting with user input devices, the user can search through any of
the individual tracks of the multimedia events to locate a point of
interest in the multimedia event and can control the presentation of the
tracks at the user output devices using traditional VCR-type commands, as
well as other play back features.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 depicts an illustrative example of a training session.
FIG. 2 depicts an illustrative embodiment of a system for recording and
playing back multimedia events in accordance with our invention.
FIG. 3A depicts a preprocessor unit in accordance with an aspect of our
invention.
FIG. 3B depicts a track mapping table, which provides instructions for
digitizing, compressing, and preprocessing tracks of the multimedia event
in accordance with an aspect of our invention.
FIG. 3C depicts a derivative track generator of the preprocessor in
accordance with an aspect of our invention.
FIG. 4 illustrates the arrangement of multimedia events in mass storage in
accordance with an aspect of our invention.
FIG. 5 shows a delivery processor for playing back multimedia events in
accordance with an aspect of our invention.
FIG. 6 depicts a user control unit in accordance with an aspect of our
invention.
FIG. 7A depicts an illustrative example of a training session, wherein
recording sources capture multimedia tracks of various aspects of the
session, in accordance with our invention.
FIG. 7B depicts the user's view of the training session, as displayed on
the user's monitor, in this embodiment of our invention.
FIG. 7C depicts the user's view of a stacked representation of a track of
the training session, as displayed on the user's monitor, in this
embodiment of our invention.
FIG. 7D depicts the user's view of a high resolution version of a track of
the training session, as displayed on the user's monitor, in this
embodiment of our invention.
FIGS. 8A, 8B, and 8C depict an illustrative flow diagram of our recording
and play back method, in accordance with our invention.
The organization and operation of the invention will be better understood
from a consideration of the detailed description of the illustrative
embodiments thereof, which follow, when taken in conjunction with the
accompanying drawing.
DETAILED DESCRIPTION OF THE INVENTION
Multimedia is a combination of different types of information (e.g., still
images, text, graphics, audio, and motion video) integrated into a single
presentation. Multimedia events include business and technical
presentations, training sessions, lectures, and meetings, comprising such
integrated combinations of different forms of information. Our invention
is a system and method for recording and playing back multimedia events
such that a user of the recorded multimedia event can review a desired
aspect of the event and maximally benefit from the exchange of information
that took place at the live event. Our system also permits a user to
intelligently search through the recorded event and control the play back
of the recorded event in a manner conducive to the information needs of
the user and within the limitations of the user's facilities.
A specific illustrative embodiment of our inventive system 200 is depicted
in FIG. 2 and comprises recording sources 201-1 through 201-N, a
preprocessor 300, an event mass storage 390, a delivery processor 400, a
distribution network 450, and user control units 500-1 through 500-M. The
recording sources 201 are devices that each capture and transmit a
different portion of a multimedia event and convert what it captures to
electronic signals, referred to herein as a track or a continuous temporal
record. Such devices include audio recorders and camcorders. Recording
sources may also include a device located internal to a presentation
device, such as an electronic white board, which records texts and
drawings written thereon. Other such recording sources may include a
computerized view graph machine, which projects view graphs stored in
computer memory onto a projection screening, and technologies such as
electronic white boards that output a digital stroke list, resulting in
higher visual quality and lower processing and storage requirements than a
video recording of a conventional white board. As shown in FIG. 2, each of
the recording sources 201-1 through 201-N transmits its record or track to
the preprocessor 300, which synchronizes the individual records in time
and processes the tracks for storage at the event mass storage 390 and for
review by users at a later time.
The preprocessor 300, as shown in FIG. 3A, includes an input interface 310,
a digitizer 320, a time stamp processor 322, local clock 325, compressor
330, a track mapping table store 335, a derivative track or continuous
temporal record generator 350, and output interface 340. Input interface
310 includes source receivers 301-1 through 301-N which receive tracks
from recording sources 201-1 through 201-N, respectively. As
illustratively shown in FIG. 3B, the track mapping table held at store 335
includes instructions for digitizing, compressing, decompressing, and
generating derivative tracks for each track of a multimedia event. This
table describes specific instructions relating to the recording and play
back of a training session, discussed infra.
The preprocessor 300 also includes a digitizer 320, which codes tracks into
digitized blocks. The technique employed for each track is dictated by the
recording source generating the track as indicated at the track mapping
table store 335. Some tracks may have been outputted from the recording
sources in digitized block form. Thus, the signals are passed through
digitizer 320 unchanged. The preprocessor 300 also includes a time stamp
processor 322, which assigns a relative time to each digitized block of
each track. The time assigned to each block is relative to the initiation
of the multimedia event. Illustratively, we assume that the multimedia
event begins at relative time, t.sub.R =0.
The same relative time is assigned to each digitized block of each track
simultaneously received at the time stamp processor 322 such that the
tracks generated from the recording sources are synchronized in time.
Local clock 325 maintains the relative time for a multimedia event and is
re-set to t.sub.r =0 upon a new multimedia event being received for
recording. The time stamp processor 322 of the synchronization processor
300 retrieves the relative time from local clock 325 for synchronizing the
tracks. The time stamp processor 322 appends the relative time information
to each digitized block in the block header.
Another component of the preprocessor 300 is the compressor 330, which
receives tracks from the time stamp processor and compresses each
individual track according to a technique indicated in the track mapping
table store 335. As indicated in the track mapping table shown in FIG. 3B,
the compression technique is dependent upon the type of information (e.g.,
audio, text, and video) being captured by the recording source. By
compressing each track using a compression technique most suitable for the
type of information contained in the track, the bandwidth required for
transmitting a multimedia event to a user is reduced. Furthermore, a track
containing information that remains essentially unchanged over a period o | | |
