Microsoft Technology Licensing, LLC

Thomas J O'Rourke

Bryan A Woodruff

George H J Shaw

George H Shaw

A method and computer program product for overcoming the inefficiencies associated with inter-buffer data transfers between separate processing components such as kernel mode drivers that are chained together. Provided is a standard mechanism for allocating and managing data buffers needed for processing data in a system, wherein multiple drivers are chained together using a standardized connection method in the connection pin instances. Drivers having different buffer requirements and capabilities may be queried and matched for easy data transition between the chained drivers requiring the least number of buffers and, hence the least expensive yet most efficient inter-buffer data transfer. Examples of buffer requirements include previous frame storage for adaptive processing, byte alignment, frame size, outstanding frames allowed, etc. The buffer requirements of an input connection pin instance may be queried by an application initializing the chained drivers. When a buffer is needed, a buffer allocator will be associated with the input pin instance, otherwise a driver will process the data in the previous existing buffer.

Method and computer program product for reducing the buffer requirements of processing components

This invention involves user mode proxy of kernel mode operations in a computer operating system. The broad contours of the invention allow drivers operating in the kernel mode of an operating system to be proxied by a corresponding user mode object. A user mode process wishing to communicate with or manipulate the kernel mode driver may perform such communication or manipulation by communicating with or manipulating the corresponding user mode proxy. The present invention has particular applicability to emerging operating systems which allow kernel mode drivers to be interconnected in order to create a processing stream in the kernel where data is passed from kernel mode driver to kernel mode driver without transitioning to user mode. User mode proxy of such kernel mode drivers allows user mode processes to manipulate such kernel mode drivers using familiar user mode protocols without the necessity of learning new kernel mode protocols.

User mode proxy of kernel mode operations in a computer operating system

Method and computer program product for reducing inter-buffer data transfers between separate processing components

A method and computer program product are presented that overcome the inefficiencies in user mode processing of multimedia data by allowing an application running as a user mode process simply to start and connect multiple blocks of kernel mode functionality in the form of drivers or filters (separate logical blocks of driver executable code). Once the kernel mode filters are set up and connected, the user mode application need not be active until notified by the filters. Such notification may occur at the end of processing or at any relevant event chosen by the application as part of the filter initiation and set up. Furthermore, a user mode application may query a kernel mode filter or driver of its capabilities and requirements so that it may properly make the connections between the different filters chained together to process a stream of data and request appropriate notifications. These connection may represent actual driver to driver data exchange, or remote connections. In one exemplary embodiment, property, method, and event sets define compliant filters and native operating system I/O constructs such as file objects are used to define the instances of connection &ldquo;pins&rdquo; that are interconnected by the third party user mode application.

Method and computer program product for interconnecting software drivers in kernel mode

A method and computer program product for synchronizing processing between two or more data streams (e.g., video and sound input) and for rate matching between two different hardware clocks that may drift with respect to one another (e.g., an originating clock represented in a timestamped data stream versus a clock actually rendering the data) in a system of interconnected software drivers running in kernel mode. The present invention overcomes the coordination complexity and inaccuracies in the prior art by providing a clocking mechanism in a system wherein multiple drivers having input and output connection pin instances are chained together. The clocking mechanism synchronizes between data streams by providing a master clock on an input pin instance of a driver that is used to synchronize with other input pin instances on other drivers and 'slave' clocks. Synchronization is achieved through event notification or stream position queries so that corresponding frames of data in separate streams are rendered together (e.g., video frames with corresponding sound track). Rate matching is achieved through monitoring a physical clock progression in comparison with a series of data stream timestamps thereby allowing adjustments to match the different clock rates. A common physical clock (e.g., PC clock) can be used as a reference for a component to translate a particular clock time to a time shared by all components with a minimum of error.

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Oulu, Finland

Thomas J O'Rourke