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: A graphics pipeline with components that process frames by portions (e.g., pixels or rows) or slices to reduce end-to-end latency. Components of a pipeline process portions of a same frame at the same time. For example, as graphics data for a frame is being generated and fills a framebuffer, once a certain portion of video data less than the whole frame (slice or sub-frame) becomes available, before the corresponding frame is finished filling the framebuffer, the next pipeline component after the framebuffer, for instance a video processor for color conversion or an encoder, begins to process the portion of the frame. While one portion of a frame is accumulating in the frame buffer, another portion of the same frame is being encoded by an encoder, and another portion of the frame might be being packaged by a multiplexer, and a network socket might start streaming the multiplexed portion.

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: Video frames of a higher-resolution chroma sampling format such as YUV 4:4:4 are packed into video frames of a lower-resolution chroma sampling format such as YUV 4:2:0 for purposes of video encoding. For example, sample values for a frame in YUV 4:4:4 format are packed into two frames in YUV 4:2:0 format. After decoding, the video frames of the lower-resolution chroma sampling format can be unpacked to reconstruct the video frames of the higher-resolution chroma sampling format. In this way, available encoders and decoders operating at the lower-resolution chroma sampling format can be used, while still retaining higher resolution chroma information. In example implementations, frames in YUV 4:4:4 format are packed into frames in YUV 4:2:0 format such that geometric correspondence is maintained between Y, U and V components for the frames in YUV 4:2:0 format.

Abstract: Disclosed herein are innovations in decoding compressed video media data. The disclosed innovations facilitate decoding operations with improved computational efficiency, faster speeds, reduced power, reduced memory usage, and/or reduced latency. In one embodiment, for example, an encoded bitstream of video media data is input from an external video content provider, the encoded bitstream being encoded according to a video codec standard. A decoder is then configured to decode the encoded bitstream based at least in part on supplemental information that identifies a property of the encoded bitstream but that is supplemental to the encoded bitstream (e.g., supplemental information that is not part of the encoded bitstream or its associated media container and that is specific (or related) to the application for which the bitstream is used and/or the standard by which the bitstream is encoded and/or encrypted).

Abstract: Techniques are described for split processing of streaming segments in which processing operations are split between a source component and a decoder component. For example, the source component can perform operations for receiving a streaming segment, demultiplexing the streaming segment to separate a video content bit stream, scanning the video content bit stream to find a location at which decoding can begin (e.g., scanning up to a first decodable I-picture, for which header parameter sets are available for decoding), and send the video content bit stream to the decoder component beginning at the location (e.g., the first decodable I-picture). The decoder component can begin decoding at the identified location (e.g., the first decodable I-picture). The decoder component can also discard subsequent pictures that reference a reference picture not present in the video content bit stream (e.g., when decoding starts with a new streaming segment).

Abstract: A host decoder and accelerator communicate across an acceleration interface. The host decoder receives at least part of a bitstream for video, and it manages certain decoding operations of the accelerator across the acceleration interface. The accelerator receives data from the host decoder across the acceleration interface, then performs decoding operations. For a given frame, settings based on an uncompressed frame header can be transferred in a different buffer of the acceleration interface than a compressed frame header and compressed frame data. Among other features, the host decoder can assign settings used by the accelerator that override values of bitstream syntax elements, can assign surface index values used by the accelerator to update reference frame buffers, and can handle skipped frames without invoking the accelerator. Among other features, the accelerator can use surface index values to update reference frame buffers, and can handle changes in spatial resolution at non-key frames.

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: In a video processing system including a video decoder, to handle frequent changes in the bit rate of an encoded bitstream, a video decoder can be configured to process a change in bit rates without reinitializing. The video decoder can be configured to reduce memory utilization. The video decoder can be configured both to process a change in bit rate without reinitializing while reducing memory utilization. In one implementation, the video processing system can include an interface between an application running on a host processor and the video decoder which allows the video decoder to communicate with the host application about the configuration of the video decoder.

Abstract: A processor that processes encoded media is configured so as to apply constraints to the encoded bitstream. Such constraints are not those required by a specification of a standard with which the encoded media is compliant; instead such constraints reflect portions of the standard that are insufficiently constrained and are applied by the processor to ensure that the processor does not experience performance degradation or errors. The constraints can be applied, for example, as a preprocessing step before reading, writing or decoding the bitstream, or while the bitstream is being decoded, or while the bitstream is being received from a transmission.

Abstract: Syntax structures that indicate the completion of coded regions of pictures are described. For example, a syntax structure in an elementary bitstream indicates the completion of a coded region of a picture. The syntax structure can be a type of network abstraction layer unit, a type of supplemental enhancement information message or another syntax structure. For example, a media processing tool such as an encoder can detect completion of a coded region of a picture, then output, in a predefined order in an elementary bitstream, syntax structure(s) that contain the coded region as well as a different syntax structure that indicates the completion of the coded region. Another media processing tool such as a decoder can receive, in a predefined order in an elementary bitstream, syntax structure(s) that contain a coded region of a picture as well as a different syntax structure that indicates the completion of the coded region.

Abstract: In a video processing system including a video decoder, to handle frequent changes in the bit rate of an encoded bitstream, a video decoder can be configured to process a change in bit rates without reinitializing. The video decoder can be configured to reduce memory utilization. The video decoder can be configured both to process a change in bit rate without reinitializing while reducing memory utilization. In one implementation, the video processing system can include an interface between an application running on a host processor and the video decoder which allows the video decoder to communicate with the host application about the configuration of the video decoder.

Abstract: Reduced latency video stabilization methods and tools generate truncated filters for use in the temporal smoothing of global motion transforms representing jittery motion in captured video. The truncated filters comprise future and past tap counts that can be different from each other and are typically less than those of a baseline filter providing a baseline of video stabilization quality. The truncated filter future tap count can be determined experimentally by comparing a smoothed global motion transform set generated by applying a baseline filter to a video segment to those generated by multiple test filter with varying future tap counts, then settings the truncated filter future tap count based on an inflection point on an error-future tap count curve. A similar approach can be used to determine the truncated filter past tap count.

Abstract: A video decoder is disclosed that uses metadata in order to make optimization decisions. In one embodiment, metadata is used to choose which of multiple available decoder engines should receive a video sequence. In another embodiment, the optimization decisions can be based on length and location metadata information associated with a video sequence. Using such metadata information, a decoder engine can skip start-code scanning to make the decoding process more efficient. Also based on the choice of decoder engine, it can decide whether emulation prevention byte removal shall happen together with start code scanning or not.

Abstract: Syntax structures that indicate the completion of coded regions of pictures are described. For example, a syntax structure in an elementary bitstream indicates the completion of a coded region of a picture. The syntax structure can be a type of network abstraction layer unit, a type of supplemental enhancement information message or another syntax structure. For example, a media processing tool such as an encoder can detect completion of a coded region of a picture, then output, in a predefined order in an elementary bitstream, syntax structure(s) that contain the coded region as well as a different syntax structure that indicates the completion of the coded region. Another media processing tool such as a decoder can receive, in a predefined order in an elementary bitstream, syntax structure(s) that contain a coded region of a picture as well as a different syntax structure that indicates the completion of the coded region.

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: Innovations in encoding and decoding of video pictures in a high-resolution chroma sampling format (such as YUV 4:4:4) using a video encoder and decoder operating on coded pictures in a low-resolution chroma sampling format (such as YUV 4:2:0) are presented. For example, high chroma resolution details are selectively encoded on a region-by-region basis. Or, as another example, coded pictures that contain sample values for low chroma resolution versions of input pictures and coded pictures that contain sample values for high chroma resolution details of the input pictures are encoded as separate sub-sequences of a single sequence of coded pictures, which can facilitate effective motion compensation. In this way, available encoders and decoders operating on coded pictures in the low-resolution chroma sampling format can be effectively used to provide high chroma resolution details.

Abstract: Techniques and systems for reducing memory usage by a decoder during a format change are disclosed. In a first example technique, discretized memory allocations for new output buffers are sequenced with discretized release operations of previously-allocated memory for previous output buffers in a manner that reduces the amount of in-use memory of a computing device during a format change. In a second example technique, the allocation of new memory for new decoder buffers associated with a new format is conditioned upon the release of previously-allocated memory for decoder buffers associated with a previous format to reduce memory usage during a format change. The first and second techniques, when combined, result in optimized reduction in memory usage by a decoder during a format change.