The present invention relates to an interactive digital system (1) enabling viewers full and active participation in experiencing a live broadcast event. Particularly, the presentation of the live event is personalized for the viewer through the provision of options, including multiple video streams, associated with different camera angles, for example, and integrated audio and graphic segments. Further, information obtained from related Web sites can be integrated into the live program.

A digital interactive system for providing full interactivity with live programming events

This document describes a profile called "RTP/AVP" for the use of the real-time transport protocol (RTP), version 2, and the associated control protocol, RTCP, within audio and video multiparticipant conferences with minimal control. It provides interpretations of generic fields within the RTP specification suitable for audio and video conferences. In particular, this document defines a set of default mappings from payload type numbers to encodings.

RTP Profile for Audio and Video Conferences with Minimal Control

We review error resilience techniques for real-time video transport over unreliable networks. Topics covered include an introduction to today's protocol and network environments and their characteristics, encoder error resilience tools, decoder error concealment techniques, as well as techniques that require cooperation between encoder, decoder, and the network. We provide a review of general principles of these techniques as well as specific implementations adopted by the H.263 and MPEG-4 video coding standards. The majority of the article is devoted to the techniques developed for block-based hybrid coders using motion-compensated prediction and transform coding. A separate section covers error resilience techniques for shape coding in MPEG-4.

Error resilient video coding techniques

An improved networked computer communications system handles arbitrary streams of data, and transports at varying speeds those streams where intermediate updates can be dropped if they are obsoleted by later arriving data updates, optimizing the utilization of network and node resources. Complex buffering by system server software allows distributed, parallel, or redundant processing, transmission, and storage for performance, reliability, and robustness. Various parameters of the system can be monitored, and the system can be reconfigured automatically based on the observations. Varied techniques reduce the perceived end-to-end latency and take advantage of software and hardware capabilities that assets connected to the system may possess. One conferencing system allows conference participants to share all or a portion of the display seen on their computer screens. The conferees may be at sites removed from each other, or may view a recorded presentation or archived conference at different times. Conference participants are either “presenters” who can modify the display or “attendees” who cannot modify the display. A pointer icon, which can be labeled to identify the conferee, is displayed on the shared image area. Each conferee can modify the position of his or her own pointer, even when not presenting, so that every participant can see what each conferee is pointing to, should a conferee choose to point to an element of the display. These and other features apply to other data streams shared in the conference or in meetings where there is no shared-image data stream.

Computer conferencing system with real-time multipoint, multi-speed, multi-stream scalability

The invention is a method for omnidirectional recognition of recognizable characters in a captured two-dimensional image. An optical reader configured in accordance with the invention searches for pixel groupings in a starburst pattern, and subjects located pixel groupings to a preliminary edge crawling process which records the pixel position of the grouping's edge and records the count of edge pixels. If two similar-sized pixel groupings are located that are of sizes sufficient to potentially represent recognizable characters, then the reader launches “alignment rails” at pixel positions substantially parallel to a centerline connecting the center points of the two similarly sized groupings. A reader according to the invention searches for additional recognizable characters within the rail area, and subjects each located pixel grouping within the rail area to a shape-characterizing edge crawling process for developing data that characterizes the shape of a pixel grouping's edge. After adjusting the orientation representation of the shape-characterizing data the reader compares the developed shape-characterizing data to previously stored shape-characterizing data to determine the character represented by the grouping on the basis of the best fit data.

Method for omnidirectional processing of 2D images including recognizable characters

High quality replay of a streaming multimedia video segment on demand is provided. The multimedia segment may be transmitted as a stream by a server system and received by a client system over a fixed bandwidth communications path. The client system receives a base layer of the stream, decodes the base layer and displays the decoded base layer at a first quality level. The client system stores at least a portion of the base layer in a cache. When a request for replay service for the multimedia segment is received from a user, for high quality replay, the client system may receive at least one enhancement layer of the stream corresponding to the stored portion of the base layer. The client system may then read the stored portion of the base layer from the cache, decode the stored portion of the base layer and the at least one enhancement layer, and display the decoded base and enhancement layers at a second quality level, higher than the first quality level.

Method of providing replay on demand for streaming digital multimedia

Video signals are encoded by dividing a current video frame into regions and generating a local complexity measure and a local quantization level for each region, where the local quantization level is selected using the local complexity measure, a previous complexity measure corresponding to a previous video frame, and a previous quantization level corresponding to the previous video frame. The complexity measures are generated using the DCT coefficients for each region. The region is encoded using the local quantization level to generate an encoded bit stream corresponding to the current video frame.

Encoding video signals using local quantization levels

In a video image compression and transmission system, quantization parameters for a block transform based video compression algorithm can be controlled by a quantizer selector so as to control compressed video frame size. The selection of the appropriate quantization parameter for the nth macroblock of a current frame is based on the cumulative number of compressed bits appearing in the first n-1 macroblocks of a current frame and a previous frame. By controlling the quantization parameter is such a manner, the overall system reacts more quickly to changes in complexity in the video sequence and allocates bits more accurately to different parts of the video frame according to a past history of bit allocation. To efficiently utilize the bandwidth of a transmission medium (such as POTS), a bit count of the contents of the transmit buffer is sent to a buffer regulator in a video controller where it is compared to a low water mark threshold. If the bit count falls below the threshold, an uncompressed video frame is scheduled for compression by a video compressor. By using the low water mark threshold, latency in the overall system is reduced and an efficient use of transmission medium bandwidth is achieved.

Method and apparatus for bit rate control in a digital video system

A display technique determines the desired size of an object to be displayed (using a distance dependent measure such as visual arc angle), determines the distance between the display unit and a user, and adjusts the size of the displayed object based on the desired size and measured distance. By repeatably determining the distance between the user and display unit, each displayed object may be dynamically adjusted to maintain an approximately constant size display, from the users point of view. The display technique may be implemented in hardware, software, or a combination of hardware and software. One benefit of the display technique is that eye strain can be reduced while working at a computer display unit.

Perceptually based display

This document specifies an RTP payload header format applicable to the
transmission of video streams generated based on the 1998 version of
ITU-T Recommendation H.263. [STANDARDS-TRACK]

Thomas R. Gardos

Papers

Method of providing replay on demand for streaming digital multimedia

Encoding video signals using local quantization levels

Method and apparatus for bit rate control in a digital video system

Perceptually based display

RTP Payload Format for the 1998 Version of ITU-T Rec. H.263 Video (H.263+)