Abstract: Innovations in reconstruction and rendering of panoramic video are described. For example, a view-dependent operation controller of a panoramic video playback system receives an indication of a view direction for an application and, based at least in part on the view direction, identifies a section of a picture of panoramic video in an input projection. The view-dependent operation controller limits operations of a color converter, video decoder, and/or streaming controller to the identified section. In this way, the panoramic video playback system can avoid performing operations to reconstruct sections of the picture of panoramic video that will not be viewed. As another example, a mapper of a panoramic video playback system re-projects at least some sample values in an input flat projection towards a center location for a view direction, producing an output flat projection, which an application can use to generate one or more screen projections.

Abstract: Innovations in opportunistic frame dropping for variable-frame-rate encoding of digital video are presented. In general, a computing system selectively drops a frame when the cost of encoding the frame (e.g., in terms of use of computational resources and/or power) is expected to outweigh the benefit of encoding the frame (e.g., in terms of better quality). For example, a frame dropping module detects whether there is significant change in a given frame relative to a control frame, which is a previous frame stored in a control frame buffer. If significant change is detected, the frame dropping module stores the given frame in the control frame buffer, thereby replacing the control frame, and passes the given frame to a video encoder. Otherwise, the frame dropping module drops the given frame without replacing the control frame in the control frame buffer and without passing the given frame to the video encoder.

Abstract: Approaches to selectively using start code emulation prevention (“SCEP”) on encoded data for media content are described herein. For example, a media encoder selectively performs SCEP processing on encoded data for media content, and sets a value of a syntax element that indicates whether or not to perform SCEP processing on the encoded data. The encoder stores the encoded data for output as part of a bitstream, where the syntax element is signaled in association with the bitstream. A media decoder receives the encoded data, determines, from the value of the syntax element, whether or not to perform SCEP processing on the encoded data, and selectively performs SCEP processing on the encoded data. In this way, the computational cost of scanning operations for SCEP processing can be avoided in many scenarios, and bit rate increases due to insertion of SCEP bytes can be limited.

Abstract: Approaches to selectively using start code emulation prevention (“SCEP”) on encoded data for media content are described herein. For example, a media encoder selectively performs SCEP processing on encoded data for media content, and sets a value of a syntax element that indicates whether or not to perform SCEP processing on the encoded data. The encoder stores the encoded data for output as part of a bitstream, where the syntax element is signaled in association with the bitstream. A media decoder receives the encoded data, determines, from the value of the syntax element, whether or not to perform SCEP processing on the encoded data, and selectively performs SCEP processing on the encoded data. In this way, the computational cost of scanning operations for SCEP processing can be avoided in many scenarios, and bit rate increases due to insertion of SCPE bytes can be limited.

Abstract: Innovations in reconstruction and rendering of panoramic video are described. For example, a view-dependent operation controller of a panoramic video playback system receives an indication of a view direction for an application and, based at least in part on the view direction, identifies a section of a picture of panoramic video in an input projection. The view-dependent operation controller limits operations of a color converter, video decoder, and/or streaming controller to the identified section. In this way, the panoramic video playback system can avoid performing operations to reconstruct sections of the picture of panoramic video that will not be viewed. As another example, a mapper of a panoramic video playback system re-projects at least some sample values in an input flat projection towards a center location for a view direction, producing an output flat projection, which an application can use to generate one or more screen projections.

Abstract: Innovations in reconstruction and rendering of panoramic video are described, including the use of a platform rendering engine to provide a screen projection based on a view direction specified for an application through an interface. For example, based at least in part on the view direction specified for the application, at least a section of panoramic video in an input projection is identified. At least some of sample values of the at least a section of the picture of panoramic video in the input projection are mapped to a screen projection. The screen projection is output for display to a buffer for the application. Thus, an application may use panoramic video, including updating a view direction, without itself having to render a screen projection for the panoramic video.

Abstract: Innovations in reconstruction and rendering of panoramic video are described. For example, a view-dependent operation controller of a panoramic video playback system receives an indication of a view direction for an application and, based at least in part on the view direction, identifies a section of a picture of panoramic video in an input projection. The view-dependent operation controller limits operations of a color converter, video decoder, and/or streaming controller to the identified section. In this way, the panoramic video playback system can avoid performing operations to reconstruct sections of the picture of panoramic video that will not be viewed. As another example, a mapper of a panoramic video playback system re-projects at least some sample values in an input flat projection towards a center location for a view direction, producing an output flat projection, which an application can use to generate one or more screen projections.

Abstract: Aspects extend to methods, systems, and computer program products for video bit stream decoding. Aspects include flexible definition and detection of surface alignment requirements for decoding hardware. Surface alignment requirements can be handled by render cropping (e.g., cropping at a video output device), through adjustment and modification of original syntax values in a video bit stream and relaxed media type negotiation in a software (host) decoder. Resolution changes can be hidden with the aligned surface allocation when applicable. Performance can be improved and power consumption reduced by using hidden resolution changes.

Abstract: Innovations in reconstruction and rendering of panoramic video are described, including the use of a platform rendering engine to provide a screen projection based on a view direction specified for an application through an interface. For example, based at least in part on the view direction specified for the application, at least a section of panoramic video in an input projection is identified. At least some of sample values of the at least a section of the picture of panoramic video in the input projection are mapped to a screen projection. The screen projection is output for display to a buffer for the application. Thus, an application may use panoramic video, including updating a view direction, without itself having to render a screen projection for the panoramic video.

Abstract: Aspects extend to methods, systems, and computer program products for transforming video bit streams for parallel decoding. Aspects of the invention can be used to break segment coding structure limitations in video bit streams. Aspects can be used to maximize parallelization of video decoding tasks, including motion compensation processing, to more efficiently utilize multi-core and multi-processor computer systems. Multiple portions of intra-segment data can be processed in parallel to speed up single frame processing. Video communication latency and memory requirements are also reduced.

Abstract: Innovations in reconstruction and rendering of panoramic video are described. For example, a view-dependent operation controller of a panoramic video playback system receives an indication of a view direction for an application and, based at least in part on the view direction, identifies a section of a picture of panoramic video in an input projection. The view-dependent operation controller limits operations of a color converter, video decoder, and/or streaming controller to the identified section. In this way, the panoramic video playback system can avoid performing operations to reconstruct sections of the picture of panoramic video that will not be viewed. As another example, a mapper of a panoramic video playback system re-projects at least some sample values in an input flat projection towards a center location for a view direction, producing an output flat projection, which an application can use to generate one or more screen projections.

Abstract: Innovations in reconstruction and rendering of panoramic video are described. For example, a view-dependent operation controller of a panoramic video playback system receives an indication of a view direction for an application and, based at least in part on the view direction, identifies a section of a picture of panoramic video in an input projection. The view-dependent operation controller limits operations of a color converter, video decoder, and/or streaming controller to the identified section. In this way, the panoramic video playback system can avoid performing operations to reconstruct sections of the picture of panoramic video that will not be viewed. As another example, a mapper of a panoramic video playback system re-projects at least some sample values in an input flat projection towards a center location for a view direction, producing an output flat projection, which an application can use to generate one or more screen projections.

Abstract: Innovations in boundary-intersection-based deblock filtering are described. For example, a video encoder or video decoder buffers multiple blocks of a reconstructed picture of a video sequence. The video encoder/decoder performs deblock filtering between at least some of the multiple blocks. As part of the deblock filtering, the video encoder/decoder selectively filters at least some sample values in a diagonal line that crosses a block-boundary intersection between two diagonally adjacent blocks. When filtering sample values at the block-boundary intersection between four blocks, the video encoder/decoder can evaluate characteristics of all four blocks and adjust sample values in a line between diagonally adjacent blocks. If there is a large visual difference between sample values at corner positions of two diagonally adjacent blocks, the difference can be smoothed by filtering sample values in a diagonal line.

Abstract: Approaches to selectively using start code emulation prevention (“SCEP”) on encoded data for media content are described herein. For example, a media encoder selectively performs SCEP processing on encoded data for media content, and sets a value of a syntax element that indicates whether or not to perform SCEP processing on the encoded data. The encoder stores the encoded data for output as part of a bitstream, where the syntax element is signaled in association with the bitstream. A media decoder receives the encoded data, determines, from the value of the syntax element, whether or not to perform SCEP processing on the encoded data, and selectively performs SCEP processing on the encoded data. In this way, the computational cost of scanning operations for SCEP processing can be avoided in many scenarios, and bit rate increases due to insertion of SCPE bytes can be limited.

Abstract: Innovations in opportunistic frame dropping for variable-frame-rate encoding of digital video are presented. In general, a computing system selectively drops a frame when the cost of encoding the frame (e.g., in terms of use of computational resources and/or power) is expected to outweigh the benefit of encoding the frame (e.g., in terms of better quality). For example, a frame dropping module detects whether there is significant change in a given frame relative to a control frame, which is a previous frame stored in a control frame buffer. If significant change is detected, the frame dropping module stores the given frame in the control frame buffer, thereby replacing the control frame, and passes the given frame to a video encoder. Otherwise, the frame dropping module drops the given frame without replacing the control frame in the control frame buffer and without passing the given frame to the video encoder.

Abstract: Aspects extend to methods, systems, and computer program products for transforming video bit streams for parallel decoding. Aspects of the invention can be used to break segment coding structure limitations in video bit streams. Aspects can be used to maximize parallelization of video decoding tasks, including motion compensation processing, to more efficiently utilize multi-core and multi-processor computer systems. Multiple portions of intra-segment data can be processed in parallel to speed up single frame processing. Video communication latency and memory requirements are also reduced.

Abstract: Aspects extend to methods, systems, and computer program products for video bit stream decoding. Aspects include flexible definition and detection of surface alignment requirements for decoding hardware. Surface alignment requirements can be handled by render cropping (e.g., cropping at a video output device), through adjustment and modification of original syntax values in a video bit stream and relaxed media type negotiation in a software (host) decoder. Resolution changes can be hidden with the aligned surface allocation when applicable. Performance can be improved and power consumption reduced by using hidden resolution changes.

Abstract: Methods, computer-storage media, and graphical user interfaces are provided for identifying and presenting rich related sites for task-oriented search queries. Upon receipt of a search query input by a user, one or more query logs are analyzed to determine if the search query is a related to a task being performed by the user. If the query is determined to be a task-oriented search query, search results are identified, as is one or more Uniform Resource Locators (URLs) related to a particular search result. The related URL is presented to the user in association with the particular search result. Additional controls, e.g., search tools that facilitate querying of those URLs determined to be relevant to a particular search result, may also be provided to aid the user in performing the task at hand.

Abstract: Innovations are provided for encoding and/or decoding video and/or image content using reduced size inverse transforms. For example, a reduced size inverse transform can be performed during encoding or decoding of video or image content using a subset of coefficients (e.g., primarily non-zero coefficients) of a given block. For example, a bounding area can be determined for a block that encompasses the non-zero coefficients of the block. Meta-data for the block can then be generated, including a shortcut code that indicates whether a reduced size inverse transform will be performed. The inverse transform can then be performed using a subset of coefficients for the block (e.g., identified by the bounding area) and the meta-data, which results in decreased utilization of computing resources. The subset of coefficients and the meta-data can be transferred to a graphics processing unit (GPU), which also results in savings in terms of data transfer.

Abstract: A video encoding system balances memory usage to store interpolated image data with processing resource usage to interpolate image data without encoding quality degradation or with better encoding quality. This balance can be achieved by identifying and interpolating subregions of a reference image. Each subregion is less than the whole reference image, but larger than a search region for any single block of an image for which motion vectors are to be computed. Each interpolated subregion of the reference image is used to compute motion vectors for multiple blocks of an image being encoded. A video encoding system can identify portions of an image being encoded for which sub-pixel resolution motion vectors are not computed. Motion vectors for such portions of the image can be computed using a reference image without interpolation.