Microsoft Technology Licensing, LLC

Other

Albert S Wang

Sanjeev Mehrotra

Philip Andrew Chou

Alexander Mohr

Navin Chaddha

Anoop Gupta

Theodore I Kamins

Tethered lid

A system and method for correcting errors and losses occurring during a receiver-driven layered multicast (RLM) of real-time media over a heterogeneous packet network such as the Internet. This is accomplished by augmenting RLM with one or more layers of error correction information. This allows each receiver to separately optimize the quality of received audio and video information by subscribing to at least one error correction layer. Ideally, each source layer in a RLM would have one or more multicasted error correction data streams (i.e., layers) associated therewith. Each of the error correction layers would contain information that can be used to replace lost packets from the associated source layer. More than one error correction layer is proposed as some of the error correction packets contained in the data stream needed to replace the packets lost in the associated source stream may themselves be lost in transmission. A preferred process for generating the error correction streams involves the use of a unique adaptation of the Forward Error Correction (FEC) techniques. This process encodes the transmission data using a linear transform which adds redundant elements. The redundancy permits losses to be corrected because any of the original data elements can be derived from any of the encoded elements. Thus, as long as enough of the encoded data elements are received so as to equal the number of the original data elements, it is possible to derive all the original elements.

Receiver-driven layered error correction multicast over heterogeneous packet networks

An adaptive entropy coder is coupled with a localized conditioning context to provide efficient compression of images with localized high frequency variations. In one implementation, an arithmetic coder can be used as the adaptive entropy coder. The localized conditioning context includes a basic context region with multiple context pixels that are adjacent the current pixel, each of the context pixels having an image tone. A state is determined for the basic context region based upon a pattern of unique image tones among the context pixels therein. An extended context region that includes the basic context region is used to identify a non-local trend within the context pixels and a corresponding state. A current pixel may be arithmetically encoded according to a previously encoded pixel having the same tone or as a not-in-context element. In one implementation, a not-in-context element may be represented by a tone in a color cache that is arranged as an ordered list of most recent not-in-context values.

Palettized image compression

An apparatus and method for encoding video frames is provided. The video frames are divided into blocks for encoding. Encoding of the video blocks utilizes motion detection, motion estimation and adaptive compression, to obtain the desired compression for a particular bit rate. Adaptive compression includes intra compression (without regard to other frames) and inter compression (with regard to other frames). Intra compression, inter compression with motion detection, and inter compression with motion estimation are performed on a block by block basis, as needed. Segmentation is provided to compare encoding of a block with encoding of its sub-blocks, and to select the best block size for encoding.

Intra compression of pixel blocks using predicted mean

A motion video signal encoder maximizes image quality without exceeding transmission bandwidth available to carry the encoded motion video signal by comparing encoded frames of the motion video signal to a desired size of frame. If the size of encoded frames differ from the desired size, encoding is adjusted to produce encoded frames closer in size to the desired size. In addition, a cumulative bandwidth error records an accumulated amount of available bandwidth. The cumulative bandwidth error is adjusted as time elapses to add to the available bandwidth and as each frame is encoded to thereby consume bandwidth. As the cumulative bandwidth error grows in magnitude above or below zero, encoding is adjusted as needed to either improve image quality to more completely consume available bandwidth or to reduce image quality to thereby consume less bandwidth and to thereby cause the cumulative bandwidth error to move toward zero. Rapid changes in the amount of change or motion in the motion video signal are detected by comparing the amount of change between two consecutive frames and filtering the amount of change with previously measured amounts of change. Encoding is pre-compensated according to the filtered measurement of rapid change.

Motion video signal encoder and encoding method

A motion video signal encoder maximizes image quality without exceeding transmission bandwidth available to carry the encoded motion video signal by comparing encoded frames of the motion video signal to a desired size of frame. If the size of encoded frames differ from the desired size, quantization is adjusted to produce encoded frames closer in size to the desired size. In addition, a cumulative bandwidth balance records an accumulated amount of available bandwidth. The cumulative bandwidth balance is adjusted as time elapses to add to the available bandwidth and as each frame is encoded to thereby consume bandwidth. If the cumulative bandwidth balance deviates from a predetermined range, quantization is adjusted as needed to either improve image quality to more completely consume available bandwidth or to reduce image quality to thereby consume less bandwidth. Rapid changes in the amount of change or motion in the motion video signal are detected by comparing the amount of change between two consecutive frames and the amount of change between the next two consecutive frames. Quantization is precompensated according to the measured rapid change. Conditional replenishment is improved by dividing macroblocks into quadrants and measuring differences between corresponding quadrants of macroblocks. As a result, sensitivity to changes along edges and corners of macroblocks is increased. In addition, sensitivity to changes in a particular macroblock is increased when an adjacent macroblock contains sufficient change to be encoded and therefore not a candidate for conditional replenishment.

Digital video signal encoder and encoding method

The present invention relates, in one aspect, to a method for processing video data that is divided into frames. The video data includes a current frame, which has an associated current macroblock, and an adjacent frame, which also has an associated macroblock. The method for processing video data involves obtaining an uncompressed current block that is a part of the current macroblock and an adjacent block that is part of the adjacent macroblock, and calculating a distance between the uncompressed current block and the adjacent block. It is determined whether the distance between the uncompressed current block and the adjacent block is acceptable. If the distance is unacceptable, then the current block is adoptively compressed.

Method and apparatus for implementing motion detection in video compression

Correction of errors and losses in a receiver-driven layered multicast (RLM) of real-time media over a network is augmented using one or more layers of error correction information. Each receiver separately optimizes the quality of received information by subscribing to at least one error correction layer. Ideally, each source layer in a RLM has one or more associated multicasted error correction data streams. Each error correction layer contains information for replacing lost packets from the associated source layer. More than one error correction layer is proposed to correct for lost packets in other error correction layers. Error correction streams are preferably generated using a pseudo-Automatic Repeat Request (ARQ) wherein a broadcaster sends both the source packets in a primary stream and delayed versions thereof in one or more redundant streams. A hybrid technique combines the psuedo-ARQ method with an adaptation of Forward Error Correction (FEC) techniques.

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Kirkland, WA, United States of America

Albert S Wang