Microsoft Technology Licensing, LLC

Thomas W Holcomb

Chih-Lung Lin

Sridhar Srinivasan

Pohsiang Hsu

Ming-Chieh Lee

Shankar Lakshmi Regunathan

Kunal Mukerjee

Bruce Chih-Lung Lin

Stacey Spears

Minghui Xia

Sanjeev Mehrotra

Regis J Crinon

Jie Liang

Cheng Chang

Jian Li

Yan Lu

Serge Smirnov

Mei-Hsuan Lu

Bharath Siravara

Geoffrey T Dunbar

Chuang Gu

William Chen

Jiahao Li

Kishore Arvind Kotteri

Xiping Zuo

Timothy E Onders

Philip Lawrence Garrett

Chun-Wei Chan

Amy Jennifer Beauford

Anil Murching

Andrey Mikhaylovic Mezentsev

Hui Gao

Shijun Sun

Shyam Sadhwani

Olivier Colle

Alexandre Vicktorovich Grigorovitch

Rebecca Claire Weiss

Sohail Baig Mohammed

Weidong Zhao

Gareth Alan Howell

Jordi Ribas-Corbera

Bakkama Srinath Reddy

Niranjan S Nayak

Matthew Bruce Andrews

William R Sanders

Shuo-Jen Wu

Chih-Iung Bruce Lin

Wei-Ge Chin

Chinweizu E Owunwanne

Techniques and tools are described for decoding jointly coded information. For example, a decoder decodes a variable length code ['VLC'] signaled at macroblock level that jointly represents a transform type signal level, transform type, and subblock pattern. The decoder decodes one or more VLCs signaled at block level, each jointly representing a transform type and subblock pattern. The decoder may select between multiple VLC tables for the VLCs signaled macroblock level and/or block level.

Decoding jointly coded transform type and subblock pattern information

A video codec uses fractional increments of quantization step size at high bit rates to permit a more continuous variation of quality and/or bit rate as the quantization scale changes. For high bit rate scenarios, the bit stream syntax includes an additional syntax element to specify fractional step increments (e.g., half step) of the normal quantizer scale step sizes.

Fractional quantization step sizes for high bit rates

Techniques are described for efficiently encoding video data by skipping evaluation of certain encoding modes based on various evaluation criteria. In some solutions, intra-block evaluation is performed in a specific order during encoding, and depending on encoding cost calculations of potential intra-block encoding modes, evaluation of some of the potential modes can be skipped. In some solutions, some encoding modes can be skipped depending on whether blocks are simple (e.g., simple vertical, simple horizontal, or both) or non-simple. In some solutions, various criteria are applied to determine whether chroma-from-luma mode evaluation can be skipped. The various solutions can be used independently and/or in combination.

Determination of coding modes for video content using order of potential coding modes and block classification

With adaptive multiple quantization, a video or other digital media codec can adaptively select among multiple quantizers to apply to transform coefficients. The switch in quantizers can be signaled at the sequence level or frame level of the bitstream syntax, or can be implicitly specified in the syntax.

Adaptive multiple quantization

Innovations in hash table construction and hash-based block matching for image encoding or video encoding are described. For example, an encoder determines hash values for base-size candidate blocks in a reference picture. The encoder stores, in a hash table, the hash values for the base-size candidate blocks. The encoder encodes a trial-size current block in a current picture. In some cases, the trial-size current block has a block size larger than the base block size. As part of the encoding, the encoder uses hash-based block matching, between base-size current blocks of the trial-size current block and the base-size candidate blocks, to identify a trial-size matching block, if any, in the reference picture. The encoder stores hash values only for the base-size candidate blocks. This can significantly reduce the computational cost and memory cost for hash table construction during encoding, without hurting compression efficiency or the overall speed of encoding.

Low-cost hash table construction and hash-based block matching for variable-size blocks

Screen content encoding mode evaluation including intra-block evaluation of multiple potential encoding modes

Techniques and tools for video coding/decoding with motion resolution switching and sub-block transform coding/decoding are described. For example, a video encoder adaptively switches the resolution of motion estimation and compensation between quarter-pixel and half-pixel resolutions; a corresponding video decoder adaptively switches the resolution of motion compensation between quarter-pixel and half-pixel resolutions. For sub-block transform sizes, for example, a video encoder adaptively switches between 8&#xd7;8, 8&#xd7;4, and 4&#xd7;8 DCTs when encoding 8&#xd7;8 prediction residual blocks; a corresponding video decoder switches between 8&#xd7;8, 8&#xd7;4, and 4&#xd7;8 inverse DCTs during decoding.

Video coding/decoding with sub-block transform sizes and adaptive deblock filtering

Techniques and tools for sub-block transform coding are described. For example, a video encoder adaptively switches between 8&#xd7;8, 8&#xd7;4, and 4&#xd7;8 DCTs when encoding 8&#xd7;8 prediction residual blocks; a corresponding video decoder switches between 8&#xd7;8, 8&#xd7;4, and 4&#xd7;8 inverse DCTs during decoding. The video encoder may determine the transform sizes as well as switching levels (e.g., frame, macroblock, or block) in a closed loop evaluation of the different transform sizes and switching levels. The encoder and decoder may use different scan patterns for different transform sizes when scanning values from two-dimensional blocks into one-dimensional arrays, or vice versa. The encoder and decoder may use sub-block pattern codes to indicate the presence or absence of information for the sub-blocks of particular blocks.

Sub-block transform coding of prediction residuals

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Thomas W Holcomb