Microsoft Technology Licensing, LLC

Paul Johan Hsieh

Sridhar Sankuratri

Damien Gerard Saint Macary

Denis Sergeyevich Shchepetov

B Anil Kumar

Hao Zhang

Asael Dror

Charles Ogden

Ricardo A Baratto

An invention is disclosed for performing differencing of graphical data in post-transform space for a remote presentation session. Graphical data is transformed from a first representation to a second representation (e.g. with a DWT), and then a difference is taken of the post-transform data and the post-transform data of the frame that preceded the current frame. This difference is then encoded and transmitted to a client, which decodes it, and creates a representation of the graphical data using the delta, and a previously determined representation of the previous frame. By performing differencing in post-transform space, fidelity of the remote presentation session is retained while it may decrease bandwidth. This may occur because the entropy of the delta representation is usually lower than a non-delta representation while the scheme retains the identical data of the final decoded image of the non-delta version of the same compression scheme.

Transform space difference compression

In various embodiments, a screen image may be divided into rectangles, and a capture component may track changed rectangles and capture the screen upon receiving an indication. For small screen updates, the capture rate may be set to &#x2dc;30 captures per second to provide a lower latency. As the screen update size increases, the capture rate may be decreased to match an allocated bandwidth. The capture rate may be increased when available bandwidth increases and decreased as bandwidth decreases. For example, the capture rate may be decreased when downstream back pressure meets predefined criteria. The capture rate change may be effected gradually to avoid jerks and jumps. Varying the capture rate by also enable audio/video synchronization with varying bandwidth variations. Some embodiments may be extended to multiple monitor solutions.

Push pull adaptive capture

An invention is disclosed for performing entropy encoding in a parallelized manner, using a GPU. In embodiments, an input sequence of integers is received, and run-length encoding is performed on any runs of zeros in parallel operations on the GPU. Then, a plurality of parallelized operations are performed on the run-length encoded sequence to entropy encode the sequence. The value N may be entropy encoded using only N and the value that precedes it in the sequence, N&#x2212;1, so the encoding may be sub-divided into multiple operations that may be performed in parallel on the GPU. After entropy encoding is performed, a bitstream may be produced using parallelized operations on the GPU.

Parallel entropy encoding on GPU

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Paul Johan Hsieh