Microsoft Technology Licensing, LLC

Shiwei Wang

Timothy Mark Moore

Ling Niu

Regis J Crinon

Humayun Mukhtar Khan

Jingyu Qiu

Walid Ali

Kandarp Jani

Kurt David Wrisley

Stephen Clifford Cooper

Kevin John Smith

Tolga Kilicli

Robert A Farrow

Tin Qian

Tim M Moore

Jiannan Zheng

Guo-Wei Shieh

Li Shen

Renato Machado De Sousa

Hiu Hok Chan

A device may generate a media stream to be shared with other users by building a media graph, comprising a series of interconnected processing units that perform various processing tasks. However, the time involved in generating the media graph may delay the initialization of the media stream, and adjusting properties of the media stream (such as resolution or codec) may result in an interruption of the media stream while a new media graph is built. Instead, a media graph cache may be provided to cache a set of media graphs, which may be interchangeably selected for rapid initialization and adjusting of media stream properties. The media component (e.g., a videocamera) may also be configured to promote rapid adjustments to some media stream properties, while maintaining other properties (e.g., field of view and white balance) for a smooth transition between media stream property sets.

Rapidly initializing and dynamically adjusting media streams

A device may generate a media stream to be shared with other users by building a media graph, comprising a series of interconnected processing units that perform various processing tasks. However, the time involved in generating the media graph may delay the initialization of the media stream, and adjusting properties of the media stream (such as resolution or codec) may result in an interruption of the media stream while a new media graph is built. Instead, a media graph cache may be provided to cache a set of media graphs, which may be interchangeably selected for rapid initialization and adjusting of media stream properties. The media component (e.g., a video camera) may also be configured to promote rapid adjustments to some media stream properties, while maintaining other properties (e.g., field of view and white balance) for a smooth transition between media stream property sets.

Video receiving capabilities of participants and source capabilities are compared and conference capabilities for providing different resolutions, frame rates, bit rate, and number of streams are determined by maintaining a conference receiving capability list updated as number and capability of participants' changes. Preferred receiving capabilities of participants are also taken into account in determining conference characteristics based on comparison with allowed capabilities.

Aggregation of video receiving capabilities

Systems, methods and computer program products for facilitating the recovery of lost real-time media packets within a computer network real-time application implementing Forward Error Control (FEC), such that server performance is not affected from a CPU and memory perspective, are disclosed. In an embodiment, a conference server that is part of a communication network compliant with the Real Time Transport Protocol (RTP) is able to avoid regenerating FEC packets by not performing any FEC coding operation on the packets unless it is flagged to indicate regeneration via an FEC (e.g., Reed-Solomon) coding is necessary. Absent the flag, the conference server updates the received FEC packet as per the RTP and transmits the packet to its ultimate destination. Such disclosed systems, methods and computer program products are independent of the nature of the media being protected and flexible enough to support a wide variety of FEC techniques.

Lost real-time media packet recovery

Video send and receive capabilities of participants are determined by the respective machines determining available combinations, as well as preferences for the receivers. Receiver capabilities are forwarded to the source for computation of negotiated video capabilities through a logic intersection of the determined capabilities based on desired number of streams and resolutions. If a resolution of a send capability exists within the receive capability, the highest frame and/or bit rate may be selected for transmission.

Multiple video stream capability negotiation

Architecture for enabling a communications endpoint to quickly recover from a packet loss, reducing duration of a signal dropout. A communications component sends a downlink of dependency-structured signals, such as audio and/or video signals using compressed frames between key frames. A multipoint control component (MCC) is located between the communications component and multiple endpoints, and distributes the downlink to the multiple endpoints. A frame caching component caches a key frame of the downlink. If a key frame is lost at one of the endpoints, the endpoint sends a packet loss report to the frame caching component. The key frame is resent from the frame caching component to the endpoint in response to the key frame loss. In this way, the frame caching component can respond to specific frame loss situations on any of the endpoints, without interfering with the performance on the other endpoints.

Error recovery in an audio-video multipoint control component

Technologies are described herein for detecting and managing congestion on a shared network link. A determination is made whether the shared network link is congested based on loss rate and round-trip time (RTT) between a computer and a receiver operatively coupled by the shared network link. Upon determining that the shared network link is congested, a back-off operation is performed on the computer. The back-off operation may reduce an allocated bandwidth of the computer on the shared network link by transforming a higher allocated bandwidth into a lower allocated bandwidth.

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Bellevue, WA, United States of America

Shiwei Wang