CROSS REFERENCE TO RELATED APPLICATIONS

This application is related to co-pending U.S. application Ser. No. 08/818,805, filed on Mar. 14, 1997, entitled “Method and Apparatus for Implementing Motion Detection in Video Compression,” U.S. application Ser. No. 08/819,507, filed Mar. 14, 1997, entitled “Digital Video Signal Encoder and Encoding Method,” U.S. application Ser. No. 08/818,804, filed on Mar. 14, 1997, entitled “Production of a Video Stream with Synchronized Annotations over a Computer Network,” U.S. application Ser. No. 08/819,586, filed on Mar. 14, 1997, entitled “Method and Apparatus for Implementing Control Functions in a Streamed Video Display System,” U.S. application Ser. No. 08/818,769, filed on Mar. 14, 1997, entitled “Method and Apparatus for Automatically Detecting Protocols in a Computer Network,” U.S. application Ser. No. 08/818,127, filed on Mar. 14, 1997, entitled “Dynamic Bandwidth Selection for Efficient Transmission of Multimedia Streams in a Computer Network,” U.S. application Ser. No. 08/819,585, filed on Mar. 14, 1997, entitled “Streaming and Display of a Video Stream with Synchronized Annotations over a Computer Network,” U.S. application Ser. No. 08/818,664, filed on Mar. 14, 1997, entitled “Selective Retransmission for Efficient and Reliable Streaming of Multimedia Packets in a Computer Network,” U.S application Ser. No. 08/819,579, filed Mar. 14, 1997, entitled “Method and Apparatus for Table-Based Compression with Embedded Coding,” U.S. application Ser. No. 08/818,826, filed on Mar. 14, 1997, entitled “Digital Video Signal Encoder and Encoding Method,” all filed concurrently herewith, U.S. application Ser. No. 08/822,156, filed on Mar. 17, 1997, entitled “Method and Apparatus for Communication Media Commands and Data Using the HTTP Protocol,” provisional U.S. application Ser. No. 60/036,662, filed on Jan. 30, 1997, entitled “Methods and Apparatus for Autodetecting Protocols in a Computer Network,” U.S. application Ser. No. 08/625,650, filed on Mar. 29, 1996, entitled “Table-Based Low-Level Image Classification System,” U.S. application Ser. No. 08/714,447, filed on Sep. 16, 1996, entitled “Multimedia Compression System with Additive Temporal Layers,” and is a continuation-in-part of U.S. application Ser. No. 08/623,299, filed on Mar. 28, 1996, entitled “Table-Based Compression with Embedded Coding,” which are all incorporated by reference in their entirety for all purposes.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to multimedia communications. More particularly, the present invention relates to the synchronous delivery of annotated multimedia streams over a diverse computer network.

2. Description of the Related Art

With the proliferation of connections to the internet by a rapidly growing number of users, the viability of the internet as a widely accepted medium of communication has increased correspondingly. Bandwidth requirements can vary significantly depending on the type of multimedia data being delivered. For example, a low resolution, low frame rate video telephone call may require only an ISDN connection, while a high resolution video broadcast of a live event to a large group of viewers may require the bandwidth of a T1 connection. Hence, the ability to deliver of multimedia data over the internet is limited by bandwidth capacity and cost of the network connection and also by the computational capability of the server and client computers.

Existing conventional internet applications, such as electronic mailers and web browers, are capable of transferring and presenting textual and graphical information. However, none of these individual internet applications effectively provide synchronous delivery of a combination of diverse multimedia streams in a coherent and integrated manner. This is because executing several independent and unrelated applications to present the diverse combination of multimedia streams on a client computer can result in a hodgepodge of poor quality, incompatible and/or incoherent presentations.

In view of the foregoing, there are desired improved techniques for reliably providing a multimedia stream such as a video and audio stream, together with annotations such as textual and graphical information in an integrated seamless package to client computer(s), while efficiently utilizing the network resources and consuming minimal computational cycles on the client computer(s).

SUMMARY OF THE INVENTION

The present invention enables client computer(s) to retrieval and display synchronized annotated multimedia streams from servers dispersed over a diverse computer network which includes local area networks (LANs) and/or wide area networks (WANs) such as the internet. Multimedia streams provided to the client computer(s) can include a compressed video stream for display in a video window and an accompanying compressed audio stream. Annotations, i.e., displayable events, include textual/graphical data in the form of HTML pages with Java applets to be displayed in one or more event windows.

In one embodiment, the video/audio and annotation streams are produced by a capture module and an author module, and then stored in stream server(s) to be provided to one or more client computer(s) upon request. The capture module compresses the video stream using a suitable compression format, depending on the desired resolution(s) and frame rate(s). The author module then generates synchronization scripts which include annotation streams which are synchronized with the compressed video/audio streams.

In this embodiment, annotation streams include annotation frames which provide either pointer(s) to the event(s) of interest or include displayable data embedded within the annotation stream. Accordingly, each annotation frame includes either an event locator or an event data. In addition, each annotation frame includes an event time marker which corresponds to the time stamp(s) of associated video frame(s) within the video stream. Examples of embedded displayable data include ticker tape data embedded within the annotation stream. Examples of event locators to displayable events include URL addresses pointing to HTML web pages. Note that an event time marker need not be identical to a corresponding video time stamp. The client computer is capable of switching to a new displayable event together with a video frame or in between two video frames.

Video/audio streams and annotation streams are provided by the stream server(s) to the client computer(s) in a coordinated manner, so that the client computer(s) is able to synchronously display the video frames and displayable event(s) in a video window and event window(s), respectively. In this embodiment, annotation streams include a flipper stream for locating HTML pages and a ticker stream which include ticker (tape) data.

The client computer also provides a table of contents displayed concurrently with the video window and the event window. The table of contents includes content labels which enable the viewer to skip forward or backward to one or more predetermined locations in the video stream.

These and other advantages of the present invention will become apparent upon reading the following detailed descriptions and studying the various figures of the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1

is a block diagram of an exemplary computer system for practicing the various aspects of the present invention.

FIG. 2

is a block diagram showing an exemplary hardware environment for practicing the annotated video-on-demand (VOD) system of the present invention.

FIG. 3

is shows a producer which includes a capture module and an author module.

FIG. 4A

is a flowchart illustrating the capture of a live video/audio stream from a video camera or from a previously stored video file.

FIGS. 4B and 4C

are flowcharts illustrating a locator annotation stream and a data annotation stream, respectively.

FIG. 5

shows an exemplary format for storing and delivering a compressed video stream.

FIG. 6

shows an exemplary customized LiveScreen display which includes a video window, a set of VCR-like control buttons, a selectable table of contents (TOC) and an HTML page window.

FIG. 7

illustrates an author tool provided by an author module for the designer to visually creating annotation streams.

FIGS. 8A and 8B

are exemplary formats illustrating a locator annotation stream and a data annotation stream, respectively.

FIG. 9

illustrates one embodiment of the client computer which includes a web browser and a browser plug-in module for interfacing a web browser with a client module.

FIGS. 10A and 10B

are flowcharts illustrating the operation of the client module.

FIG. 11

is a flowchart illustrating the use of a table of content with content labels enabling a viewer to skip forward or backward to predetermined locations in the video/audio stream.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will now be described in detail with reference to a few preferred embodiments thereof as illustrated in the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art, that the present invention may be practiced without some or all of these specific details. In other instances, well known process steps have not been described in detail in order to not unnecessarily obscure the present invention.

FIG. 1

is a block diagram of an exemplary computer system

100

for practicing the various aspects of the present invention. Computer system

100

includes a display screen (or monitor)

104

, a printer

106

, a floppy disk drive

108

, a hard disk drive

110

, a network interface

112

, and a keyboard

114

. Computer system

100

includes a microprocessor

116

, a memory bus

118

, random access memory (RAM)

120

, read only memory (ROM)

122

, a peripheral bus

124

, and a keyboard controller

126

. Computer system

100

can be a personal computer (such as an Apple computer, e.g., an Apple Macintosh, an IBM personal computer, or one of the compatibles thereof), a workstation computer (such as a Sun Microsystems or Hewlett-Packard workstation), or some other type of computer.

Microprocessor

116

is a general purpose digital processor which controls the operation of computer system

100

. Microprocessor

116

can be a single-chip processor or can be implemented with multiple components. Using instructions retrieved from memory, microprocessor

116

controls the reception and manipulation of input data and the output and display of data on output devices.

Memory bus

118

is used by microprocessor

116

to access RAM

120

and ROM

122

. RAM

120

is used by microprocessor

116

as a general storage area and as scratch-pad memory, and can also be used to store input data and processed data. ROM

122

can be used to store instructions or program code followed by microprocessor

116

as well as other data.

Peripheral bus

124

is used to access the input, output, and storage devices used by computer system

100

. In the described embodiment(s), these devices include display screen

104

, printer device

106

, floppy disk drive

108

, hard disk drive

110

, and network interface

112

. Keyboard controller

126

is used to receive input from keyboard

114

and send decoded symbols for each pressed key to microprocessor

116

over bus

128

.

Display screen

104

is an output device that displays images of data provided by microprocessor

116

via peripheral bus

124

or provided by other components in computer system

100

. Printer device

106

when operating as a printer provides an image on a sheet of paper or a similar surface. Other output devices such as a plotter, typesetter, etc. can be used in place of, or in addition to, printer device

106

.

Floppy disk drive

108

and hard disk drive

110

can be used to store various types of data. Floppy disk drive

108

facilitates transporting such data to other computer systems, and hard disk drive

110

permits fast access to large amounts of stored data.

Microprocessor

116

together with an operating system operate to execute computer code and produce and use data. The computer code and data may reside on RAM

120

, ROM

122

, or hard disk drive

120

. The computer code and data could also reside on a removable program medium and loaded or installed onto computer system

100

when needed. Removable program mediums include, for example, CD-ROM, PC-CARD, floppy disk and magnetic tape.

Network interface circuit

112

is used to send and receive data over a network connected to other computer systems. An interface card or similar device and appropriate software implemented by microprocessor

116

can be used to connect computer system

100

to an existing network and transfer data according to standard protocols.

Keyboard

114

is used by a user to input commands and other instructions to computer system

100

. Other types of user input devices can also be used in conjunction with the present invention. For example, pointing devices such as a computer mouse, a track ball, a stylus, or a tablet can be used to manipulate a pointer on a screen of a general-purpose computer.

The present invention can also be embodied as computer readable code on a computer readable medium. The computer readable medium is any data storage device that can store data which can be thereafter be read by a computer system. Examples of the computer readable medium include read-only memory, random-access memory, magnetic data storage devices such as diskettes, and optical data storage devices such as CD-ROMs. The computer readable medium can also be distributed over a network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion.

FIG. 2

is a block diagram showing an exemplary hardware environment for practicing the annotated video-on-demand (VOD) system of the present invention. The VOD system includes a production station

210

, a stream server

220

, at least one web server

230

and at least one client computer

240

, each of which can be implemented using computer system

100

described above. Stream server

220

and web server

230

are coupled to client computer

240

via a computer network

290

, e.g., the internet. Note that the disclosed hardware environment is exemplary. For example, production station

210

and stream server

220

can be implemented using two separate computer systems or using one computer system. In addition, if production station

210

and stream server

220

are implemented on separate computer systems as shown in

FIG. 2

, an optional direct connection (not shown) between production station

210

and stream server

220

can provide faster uploads of compressed video and annotation streams. In the following description, an audio stream optionally accompanies each video stream.

A producer

215

, installed in production station

210

, is a user-friendly tool for use by a designer

219

to create a synchronization script which includes annotation stream(s). The annotation stream(s) define the content(s) of a LiveScreen display

245

to be displayed on client computer

240

for a viewer

249

. LiveScreen

245

display provides a graphical user interface (GUI) with multiple windows for synchronously displaying a video stream from stream server

220

and at least one displayable event stream. Examples of displayable events include textual/graphical information such as HTML-scripted web page(s) from web server

230

.

In one embodiment, as shown in

FIG. 3

, producer

215

includes a capture module

317

and an author module

318

. Production station

210

includes 16 MB of RAM and a 1 GB hard disk drive for capturing and storing an uncompressed or precompressed video stream. Sources for generating video streams include a video camera

312

, a video cassette recorder (VCR) (not shown) or a previously digitized video file

314

, e.g., a Video for Windows (.avi) file. For ease of installation and use by designer

219

, producer

215

is implemented in a host environment which includes a window-based operating system such as Microsoft Windows 95 and a web browser such as Netscape's Navigator 3.x. (Appendix A is a detailed user manual for one implementation of producer

215

).

Referring also to the flowchart of

FIG. 4A

, in step

410

capture module

317

captures a live video/audio stream from video camera

312

or from the previously stored video file

314

. If video camera

312

provides an analog video stream, e.g., an NTSC signal, a hardware capture card (not shown) provides the required conversion from the analog video stream to a digitized video stream. Because temporary storage of uncompressed video data is memory intensive, some form of pre-compression can be used to reduce the memory storage requirement of the input video stream during capture step

410

and prior to compression step

420

.

In step

420

, capture module

420

compresses the digitized video stream using a suitable compression technique. In this embodiment, depending on the bandwidth capacity of the connection provided by network

290

between stream server

220

and client computer

240

, e.g., a POTS modem, ISDN or Ethernet, a suitable frame resolution and frame rate combination is selected. A compression algorithm based on the H263 standard (see co-pending applications VXT 702 and 718) is used for compressing lower bandwidth video streams, e.g., at less than 56 kbps. Alternatively, a Vxpress format ( see co-pending application VXT 712) is used for compressing higher bandwidth video streams.

FIG. 5

shows an exemplary format

500

for storing and delivering a compressed video stream.

A similar format can also be used to store and deliver a separate compressed audio stream. It is also possible to combine, e.g., interleave a compressed video and audio data into one stream for delivery. Audio encoders/decoders (codecs) are available from a number of commercial sources. Examples include ToolVox from Voxware Inc., 305 College Road East, Princeton, N.J. 08540, and QCELP from QUALCOMM Inc., 10555 Sorrento Valley Road, San Diego, Calif. 92121.

Referring back to

FIGS. 3 and 4A

, in step

430

, designer

219

uses author module

318

to compose a suitable LiveScreen display format which defines the layout of LiveScreen display

245

at client computer

240

.

FIG. 6

shows an exemplary customized LiveScreen display

600

which includes a video window

610

, a set of VCR-like control buttons

620

, a selectable table of contents (TOC)

630

and an HTML page window

640

. Examples of other displayable event windows include but is not limited to ticker tape windows (not shown). In this implementation, LiveScreen templates

319

are available for designer

219

to use as starting points for composing customized LiveScreen formats.

FIG. 7

illustrates an author tool

700

provided by author module

318

for designer

219

to visually creating annotation streams (step

440

). There are two types of annotation streams. The first type of annotation streams are data annotation streams in which the displayable event data are embedded within the annotation streams. Examples of data annotation streams include ticker annotation streams which include ticker tape data embedded within the annotation stream. The second type of annotation streams are locator annotation streams in which the displayable data is either too cumbersome and/or is continually evolving to be embedded as static data within the annotation stream. Instead, event locator(s) pointing to the location of the displayable data are stored in the annotation streams instead of the displayable data. Examples include URL addresses pointing to HTML pages.

Designer

219

may view frames from video stream

500

displayed in video window

720

for referencing and selecting appropriate time stamps to use in generating annotation streams. Within video window

720

, VCR function buttons, e.g., a rewind button

724

, a play button

726

and a fast forward button

728

, are available for designer

219

to quickly traverse video stream

500

. Since video window

720

is provided as a convenience for designer

219

, if designer

219

has prior knowledge of the content of the video stream, designer

219

may proceed with the generation of the annotation streams without viewing video window

720

.

As shown in

FIG. 7

, author tool

700

displays a flipper time track

750

, a video time track

760

, an audio time track

770

, a ticker time track

780

and a table of contents (TOC) time track

790

. Flipper time track

750

and ticker time track

780

aid designer

217

in generating a flipper annotation stream and a ticker annotation stream, respectively. Another visual control aid, zoom bar

716

, enables designer

219

to select the respective portions of the complete time tracks

750

,

760

,

770

,

780

and

790

, as defined by start time indicator

712

and end time indicator

718

, which is currently displayed by author tool

700

.

In accordance with one aspect of the invention, annotation frames are generated by designer

217

to form customized annotation streams (step

440

. A time hairline

715

spanning time tracks

750

,

760

,

770

,

780

and

790

provides designer

217

with a visual aid to select an appropriate time, displayed in time indicator

714

, for synchronizing a displayable event. The exemplary format of time indicators

712

,

714

and

718

are “hours:minutes:seconds”.

FIGS. 4B and 8A

are a flowchart and an exemplary format, respectively, illustrating a locator annotation stream

800

a

. Locator annotation stream

800

a

includes an annotation stream header

810

a,

and a plurality of annotation frames

820

a

,

830

a

,

840

a

, . . .

890

a

. Each annotation frame includes an event locator and an event time marker, e.g., annotation frame

820

a

includes event locator

822

a

and event time marker

824

a

. One example of a locator annotation stream is a flipper stream. Flipper time track

750

provides a convenient way to select suitable event time marker values, e.g., flipper time markers

751

,

752

,

753

,

754

, for the respective event locators. For example, URL addresses (event locators) pointing to HTML pages enable client computer

240

to subsequently retrieve textual and/or graphical elements to be displayed at predetermined time as defined by the time markers of the flipper stream.

FIGS. 4C and 8B

are a flowchart and an exemplary format, respectively, illustrating a data annotation stream

800

b

. Locator annotation stream

800

a

includes an annotation stream header

810

a

, and a plurality of annotation frames

820

a

,

830

a

,

840

a

, . . .

890

a

. Each annotation frame includes an event locator and an event time marker, e.g., annotation frame

820

a

includes event locator

822

a

and event time marker

824

a

. One example of a data annotation stream is a ticker stream. The generation of the ticker stream is somewhat similar to that of the flipper stream. However, in the case of the ticker stream, instead of event locators, displayable data is embedded directly into the ticker stream as event data.

When author module

318

has completed building an annotation stream, e.g., the flipper stream, the annotation stream is given a file name and loaded into a convenient server, e.g., stream server

220

, for subsequent retrieval by client computer

240

. The use of the annotation streams is described in greater detail below with the description of client computer

240

.

In accordance with another aspect of the invention, LiveScreen display

600

also includes a table of contents (TOC)

630

, enabling viewer

249

at client computer

240

to skip forward or backward to a point within the entire video/audio stream

500

. TOC

630

include one or more content labels, each indexed to a corresponding time stamp in video stream

500

, as defined by TOC time markers

791

,

792

,

793

,

794

in LiveScreen display

600

.

Referring now to

FIG. 9

, in one embodiment of the present invention, client computer

240

includes a web browser

950

and a browser plug-in module

952

for interfacing web browser

950

with a main client module

960

. Client module

960

includes an event registry

962

, playout buffer(s)

966

, video/audio decoder(s)

964

, video/audio renderer(s)

965

and one or more dynamically loadable event applet(s), e.g., flipper applet

967

, ticker applet

968

and VCR applet

969

. In this embodiment, event registry

962

also functions as an annotation interpreter

963

.

FIG. 10A

is a flowchart illustrating the operation of client module

960

. Assume that viewer

249

has not previously loaded client module

960

in client computer

240

, but has already loaded a web browser

950

, e.g., Netscape's Navigator (step

1010

). Viewer

249

surfs the world-wide web (www) via the internet and locates a web site of interest to viewer

249

. Typically, the web site of interest is hosted on web server

230

. Accordingly, a target web page is downloaded from web server

230

and displayed on client computer

240

.

The target web page includes a link to a customized LiveScreen display, e.g., display

600

. If client module

960

has not been previously loaded, client module

960

is now loaded over web browser

950

for processing video/audio and annotation streams (step

1020

). Depending on the implementation, a copy of client module

960

may be available from the web site of interest. Alternatively, the target web page may provide a HTML link to another web server which has an updated copy of client module

960

.

Referring now to

FIG. 10B

, first, browser plug-in module

952

is installed over web browser

950

(step

1022

). As discussed above, plug-in module

952

provides the interface between client module

960

and web browser

950

. The target web page provides a HTML link to the format for LiveScreen display

600

. The LiveScreen display format is retrieved and display

600

is installed on client computer

240

using web browser

950

(step

1024

).

Next, event registry

962

begins a registration/load process of the event applets, e.g., flipper applet

967

, ticker applet

968

and VCR applet

969

(step

1026

). Event registry

962

is capable of dynamically registering event applets, i.e., registry

962

is capable of registering additional event applets after the initial registration process, thereby making it possible to add new event windows to LiveScreen display

600

of client computer

240

without having to re-install client module

960

. Each event applet has a tag which includes attributes such as Java class, command stream format RTP://server name and file name (location of stream). During the registration process, each applet provides event registry

962

with a list of its respective function(s). Appendix B includes detailed instructions for interfacing event applets, coded in Java, with browser plug-in module

952

.

Referring back to

FIG. 10A

, encoded video/audio frames and associated annotation frames are streamed from stream server

220

to client computer

240

for synchronous display (step

1030

). Streaming video and audio streams over a network is very efficient because streaming eliminates the need for a large buffer at client computer

240

. In addition, streaming also provides flexibility, e.g., switching video sources midstream is possible without wasting network resources since streaming is based on a pseudo just-in-time (JIT) protocol and does not involve downloads of the entire video stream prior to display at client computer

240

. If the underlying transmission protocol is HTTP, then video, audio and annotation packets are initially “pulled” by client computer

240

from server

220

using HTTP “get” packet(s).

Next, the encoded video/audio streams are decoded by decoder

964

, i.e., decompressed using a suitable technique, and then displayed at client computer

240

by renderer

965

(step

1040

). (See co-pending applications VXT

702

,

712

and

718

).

In this implementation, annotation frames streamed from stream server

220

are encoded in Visual Basic script. As shown in

FIGS. 8A and 8B

, annotation streams

800

a

,

800

b

include stream headers

810

a

,

810

b

, respectively, followed by one or more annotation frames. Annotation interpreter

963

parses annotation frames in real-time in the form of messages from stream server

220

, and converts the messages into a C++ function calls for the respective event applets (step

1050

). In the case of flipper stream

800

a

, each annotation frame includes a HTML address and an event time marker. In the case of ticker stream

800

b

, each annotation frame includes ticker data and an event time marker. Note that an event time marker need not be identical to a corresponding video time stamp. Client computer

240

is capable of switching to a new displayable event together with a video frame or in between two video frames.

While the contents of annotation frames may differ, from the perspective of stream streamer

220

, the event data or event locator are simply arguments to be passed on to client computer

240

to be processed by client computer

240

. Hence, all annotation frames are processed in the same manner by stream server

220

, i.e., annotation frames are streamed to client computer

240

at the appropriate time in accordance with their respective event time markers.

Further, since the video and annotation streams are handled synchronously but separately by video decoder

964

and annotation interpreter

963

, respectively, steps

1040

and

1050

can occur concurrently or consecutively. As discussed above, event registry

962

is capable of dynamic registration of event applets. Accordingly, annotation interpreter

963

is adaptable, and capable of automatic installation and linking of new event applet(s) to add new class(es) of displayable events for client computer

240

.

After registering with event registry

962

, flipper applet

967

provides the location of the flipper stream to browser

950

which then begin receiving the flipper stream from stream server

220

. Flipper annotation frames are provided by stream server

220

synchronously with the video/audio frames to client module

960

so that the annotations, i.e., displayable events can be synchronized for display at client computer

240

(step

1060

). In this example, URL addresses, for synchronizing HTML page flips with video stream are provided to web browser

950

thereby permitting client computer

240

to subsequently retrieve and display various textual and graphical elements changing at predetermined points corresponding to the timeline of the video stream. Note that HTML pages can be retrieved from one or more web server(s)

230

.

Similarly, after registering with event registry

962

, ticker (tape) applet

968

provides the location of the ticker stream to browser

950

which then begins receiving the ticker stream from stream server

220

. Ticker annotation frames are provided by stream server

220

synchronously with the video/audio frames so that the annotations, i.e., displayable ticker data can be synchronized for display at client computer

240

at predetermined points corresponding to the timeline of the video stream.

Many types and combinations of display windows and/or content are possible. For example, another window may be used to display documents delivered via a data annotation stream and a “PowerPoint” viewer. Another exemplary variation includes providing an annotation stream to an “ActiveX” object for viewing displayable event(s) associated with a HTML page.

After registration, VCR control applet

969

provides VCR-like control buttons

620

such as play, rewind, fast forward, pause, and live-play. Note that since VCR buttons are under the interactive control of viewer

249

, activation points in the time line cannot be predicted in advance, and so no annotation stream is used. (See co-pending application VXT 704) Instead, when a VCR-type function such as rewind (“REW”) is activated, VCR applet

969

sends an appropriate message is sent to stream server

220

, which resets both the video/audio streams and annotation stream(s) to the viewer selected point in time.

As shown in

FIG. 11

, a table of content

630

with content labels enables viewer

249

to skip forward or backward to predetermined locations in the video/audio stream. First, viewer

249

selects a content label of interest (step

1110

). Examples of suitable content labels are section headings of the video stream. Next, client module

960

sends a message to stream server

220

with the time stamp of an I-frame from the video stream whose location is close to selected content label (step

1120

). In this embodiment, an I-frame is a video frame which includes data for a complete video frame. Although computationally more intensive, it is also possible to select a P-frame and then reconstructed a complete video starting from a neighboring I-frame close to the selected P-frame.

In step

1130

, stream server

220

resets the video/audio stream and the annotation stream(s) to correspond to the selected I-frame. Stream server

220

is now ready to resume transmission of the video/audio stream and the annotation stream(s) to client computer

240

for viewing (step

1140

).

The present invention may be practiced with network performance improvement techniques such as dynamic bandwidth switching and selective retransmission. (See co-pending application VXT 706 and 711) Other techniques include additive layers with increasing transmission/retransmission priority, allowing client computer

240

to drop higher resolution/frame rate information which have been assigned lower priority (see VXT 603).

While this invention has been described in terms of several preferred embodiments, there are alterations, permutations, and equivalents which fall within the scope of this invention. For example, although the present invention is described using a H263-based and a vector quantization-based techniques, the methods and apparatuses of the present invention are equally applicable other compression/decompression techniques. It is therefore intended that the following appended claims be interpreted as including all such alterations, permutations, and equivalents as fall within the true spirit and scope of the present invention.