Microsoft Technology Licensing, LLC

Keman Yu

Shipeng Li

Jiang Tao Li

Tielin He

Yunfeng Lin

Jizheng Xu

Shan Lu

In a first exemplary media implementation, one or more processor-accessible media include processor-executable instructions that, when executed, direct a device to perform actions including: comparing an accuracy indicator to at least one threshold, the accuracy indicator corresponding to a reference macroblock selected for a target macroblock; ascertaining a refinement case from multiple refinement cases based on the comparing, each refinement case of the multiple refinement cases defining multiple test points in relation to the reference macroblock; and analyzing the ascertained refinement case with regard to the target macroblock. In a second exemplary media implementation, one or more media include processor-executable instructions that, when executed, direct a device to perform actions including: determining if two chrominance sums have magnitudes that are each less than a first product and four luminance sums have magnitudes that are each less than a second product; and if so, forwarding all zero values for a macroblock.

Low complexity real-time video coding

Systems and methods for video communication are described. In one aspect, network bandwidth conditions are estimated. Bi-level or full-color video is then transmitted over the network at transmission bit rates that are controlled as a function of the estimated bandwidth conditions. To this end, network bandwidth capability is periodically probed to identify similar, additional, or decreased bandwidth capabilities as compared to the estimated bandwidth conditions. Decisions to hold, decrease, or increase the video transmission bit rate are made based on the estimated bandwidth conditions in view of the probing operations. When the transmission bit rate is increased or decreased, the transmission bit rate is calculated to target an upper or lower bit rate, both of which are indicated by the estimated bandwidth conditions. Bi-level video communication is switched to full-color video transmission, or vice versa, when the video transmission bit rate respectively reaches the upper bit rate or the lower bit rate.

Bi-level and full-color video combination for video communication

Systems and methods for bi-directional temporal error concealment are described. In one aspect, a lost frame is detected during encoded video decoding operations. Bi-directional estimations for each pixel of the lost frame are calculated to generate a current frame for bi-directional temporal error concealment of the lost frame.

Bi-directional temporal error concealment

Systems and methods for variable block size early termination for video coding are described. In one aspect a set of thresholds are selected based on block sizes in a video encoding scheme. The thresholds include a respective threshold for each block size used by the encoding scheme. For each macroblock of multiple macroblocks in a video data sequence, blocks in the macroblock are evaluated in view of respective threshold(s) to determine if motion estimation operations can be terminated prior to evaluating remaining blocks in the macroblock.

Variable block size early termination for video coding

A model-based rate control mechanism involves the percentage of less probable symbols (LPS). The mechanism is first described in the context of bi-level video and subsequently extended for multi-level video by applying it to individual bit planes thereof. A model parameter represents a relationship between an LPS reduction ratio and a bit-count reduction ratio. The model parameter thusly facilitates transforming a targeted bit-count into an LPS reduction ratio. The LPS reduction ratio can be attained by adjusting a threshold band half-width wherein LPS pixels within the threshold band are converted to more probable symbols (MPSs). In a described implementation, a threshold band half-width is set so as to achieve a desired LPS reduction ratio. The desired LPS reduction ratio is determined based on a desired bit-count reduction ratio and the model parameter. The desired bit-count reduction ratio is determined using a bit plane complexity value and a targeted bit-count.

Video rate control

Video image quality may be improved by correcting exposure levels and/or enhancing contrast amounts on each frame. One or more of the following phases may be implemented: skin-color model building, face detecting, exposure level correcting, and contrast enhancing. In a described implementation, a Gaussian skin-color model is built for each image frame during runtime. The Gaussian skin-color model is built with training pixels that are selected responsive to a defined skin color range, which is created offline from manually-selected skin pixels of multiple test sequences. In another described implementation, each pixel of an image frame is re-exposed using a ratio of contrast amount control variables (CACVs). More specifically, a pixel may be converted to a corresponding light intensity using a first CACV, and the corresponding light intensity may be reconverted to a pixel using a second CACV to enhance the contrast and possibly reduce fuzziness of the image frame.

Video image quality

Generation, coding and transmission of an effective video form, scalable portrait video. As an expansion to bi-level video, portrait video is composed of more gray levels, and therefore possesses higher visual quality while it maintains a low bit rate and low computational costs. Portrait video is a scalable video in that each video with a higher level always contains all the information of the video with a lower level. The bandwidths of 2-4 level portrait videos fit into the bandwidth range of 20-40 Kbps that GPRS and CDMA 1X can stably provide. Therefore, portrait video is very promising for video broadcast and communication on 2.5 G wireless networks. With portrait video technology, this system and method is the first to enable two-way video conferencing on Pocket PCs and Handheld PCs.

System and method for scalable portrait video

Video image quality may be improved by correcting exposure levels and/or enhancing contrast amounts on each frame. One or more of the following phases may be implemented: skin-color model building, face detecting, exposure level correcting, and contrast enhancing. In a described implementation, each pixel of an image frame is re-exposed using a ratio of contrast amount control variables (CACVs). More specifically, a pixel may be converted to a corresponding light intensity using a first CACV, and the corresponding light intensity may be reconverted to a pixel using a second CACV to enhance the contrast and possibly reduce fuzziness of the image frame. In another described implementation, a Gaussian skin-color model is built for each image frame during runtime. The Gaussian skin-color model is built with training pixels that are selected responsive to a defined skin color range, which is created offline from manually-selected skin pixels of multiple test sequences.

To encode image and video data using a transform having low computational complexity and high compression efficiency, all elements of the matrix can be expressed with power-of-2 elements, with a template of the matrix approximating a DCT matrix.

Low-complexity 2-power transform for image/video compression

Generation, coding and transmission of an effective video form, scalable portrait video. As an expansion to bi-level video, portrait video is composed of more gray levels, and therefore possesses higher visual quality while it maintains a low bit rate and low computational costs. Portrait video is a scalable video in that each video with a higher level always contains all the information of the video with a lower level. The bandwidths of 2&#x2013;4 level portrait videos fit into the bandwidth range of 20&#x2013;40 Kbps that GPRS and CDMA 1X can stably provide. Therefore, portrait video is very promising for video broadcast and communication on 2.5 G wireless networks. With portrait video technology, this system and method is the first to enable two-way video conferencing on Pocket PCs and Handheld PCs.

A video compression/decompression procedure that provides a reliable, low bit video bit stream with some color features over relatively low bandwidth wireless networks. The procedure provides some pleasing color features in a video bit stream without needing a large bandwidth network like those needed for example for a MPEG 4 bit stream. The procedure provides the color features by using a bi-level Y luminance component and a number of UV chrominance combinations. The bi-level Y-component outlines the features of the image, while the UV-combinations describe the basic color information of the image.

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Beijing, China

Keman Yu