Abstract: Techniques and tools for video coding/decoding with sub-block transform coding/decoding and re-oriented transforms are described. For example, a video encoder adaptively switches between 8×8, 8×4, and 4×8 DCTs when encoding 8×8 prediction residual blocks; a corresponding video decoder switches between 8×8, 8×4, and 4×8 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. When a video encoder or decoder uses spatial extrapolation from pixel values in a causal neighborhood to predict pixel values of a block of pixels, the encoder/decoder can use a re-oriented transform to address non-stationarity of prediction residual values.

Abstract: The coded block parameters used to code blocks of image samples into structures called macroblocks are compressed more efficiently by exploiting the correlation between chrominance and luminance blocks in each macroblock. In particular, the coded block pattern for chrominance and luminance are combined into a single parameter for the macroblock and jointly coded with a single variable length code. To further enhance coding efficiency, the spatial coherence of coded block patterns can be exploited by using spatial prediction to compute predicted values for coded block pattern parameters.

Abstract: Quality settings established by an encoder are adjusted based on information associated with regions of interest (“ROIs”). For example, quantization step sizes can be reduced (to improve quality) or increased (to reduce bit rate). ROIs can be identified and quality settings can be adjusted based on input received from a user interface. An overlap setting can be determined for a portion of a picture that corresponds to an ROI overlap area. For example, an overlap setting is chosen from step sizes corresponding to a first overlapping ROI and a second overlapping ROI, or from relative reductions in step size corresponding to the first ROI and the second ROI. ROIs can be parameterized by information (e.g., using data structures) that indicates spatial dimensions of the ROIs and quality adjustment information (e.g., dead zone information, step size information, and quantization mode information).

Abstract: An audio encoder implements multi-channel coding decision, band truncation, multi-channel rematrixing, and header reduction techniques to improve quality and coding efficiency. In the multi-channel coding decision technique, the audio encoder dynamically selects between joint and independent coding of a multi-channel audio signal via an open-loop decision based upon (a) energy separation between the coding channels, and (b) the disparity between excitation patterns of the separate input channels. In the band truncation technique, the audio encoder performs open-loop band truncation at a cut-off frequency based on a target perceptual quality measure. In multi-channel rematrixing technique, the audio encoder suppresses certain coefficients of a difference channel by scaling according to a scale factor, which is based on current average levels of perceptual quality, current rate control buffer fullness, coding mode, and the amount of channel separation in the source.

Abstract: An improved loss recovery method for coding streaming media classifies each data unit in the media stream as an independent data unit (I unit), a remotely predicted unit (R unit) or a predicted data unit (P unit). Each of these units is organized into independent segments having an I unit, multiple P units and R units interspersed among the P units. The beginning of each segment is the start of a random access point, while each R unit provides a loss recovery point that can be placed independently of the I unit. This approach separates the random access point from the loss recovery points provided by the R units, and makes the stream more impervious to data losses without substantially impacting coding efficiency. The most important data units are transmitted with the most reliability to ensure that the majority of the data received by the client is usable. The I units are the least sensitive to transmission losses because they are coded using only their own data.

Abstract: A video bitstream can be encoded and sent over a computer network to a decoding computer system. The bitstream can follow a regular prediction structure when an encoding computer system is not notified of lost data from the bitstream. A notification of lost data in the bitstream can be received. The lost data can include at least a portion of a reference frame of the bitstream. In response, a synchronization predicted frame can be dynamically encoded with a prediction that references one or more other previously-sent frames in the bitstream and that does not reference the lost data. The synchronization predicted frame can be inserted in the bitstream in a position where the regular prediction structure would have dictated inserting a different predicted frame with a prediction that would have referenced the lost data according to the regular prediction structure.

Abstract: Optimization of conference call encoding processes is provided. A first client of a multi-party conference call may receive client capability data, including video scalability support, from each of the other clients to the conference call. Based on the client capability data and the transmission capabilities of the first client, including video scalability support, the first client may determine a total number of data streams and properties for each data stream, such that the total number of data streams and the plurality of properties for each data stream are optimized and supported by the respective client capability data and the transmission capabilities. Subsequently, the first client generates one or more data streams according to the total number of data streams and the properties that were determined for each data stream and transmits the one or more data streams to the other clients of the conference call.

Abstract: Concepts and technologies are described herein for multi-layer rate control. In accordance with the concepts and technologies disclosed herein, a video server obtains video data and encodes the video data into a multi-layer video stream. Layers of the video stream cart be output buffers and the buffers can be monitored to determine bit usage. A rate controller can obtain bit usage feedback for each layer of the encoded video stream and determine, based upon the bit usage feedback, a quantization parameter associated with each layer of the encoded video stream. In determining the quantization parameters, the rate controller can consider not only bitrates of the entire encoded video stream, but also bitrates and bit usage feedback associated with each layer of the encoded video stream. Further encoding can be based upon the quantization parameters determined by the video server.

Abstract: Innovations described herein provide a framework for advertising encoder capabilities, initializing encoder configuration, and signaling run-time control messages for video coding and decoding. For example, an encoding controller receives a request for encoder capability data from a decoding host controller, determines the capability data, and sends the capability data in reply. The capability data can include data that indicate a number of bitstreams, each providing an alternative version of input video, as well as data that indicate scalable video coding capabilities. The decoding host controller creates stream configuration request data based on the encoder capability data, and sends the configuration request data to the encoding controller. During decoding, the decoding host controller can create and send a control message for run-time control of encoding, where the control message includes a stream identifier for a bitstream and layer identifiers for a given layer of the bitstream.

Abstract: In various respects, hardware-accelerated decoding is adapted for decoding of video that has been encoded using scalable video coding. For example, for a given picture to be decoded, a host decoder determines whether a corresponding base picture will be stored for use as a reference picture. If so, the host decoder directs decoding with an accelerator such that the some of the same decoding operations can be used for the given picture and the reference base picture. Or, as another example, the host decoder groups encoded data associated with a given layer representation in buffers. The host decoder provides the encoded data for the layer to the accelerator. The host decoder repeats the process layer-after-layer in the order that layers appear in the bitstream, according to a defined call pattern for an acceleration interface, which helps the accelerator determine the layers with which buffers are associated.

Abstract: Innovations described herein facilitate the addition of temporal scalability to non-scalable bitstreams. For example, a bitstream rewriter receives units of encoded video data for a non-scalable bitstream from components of a hardware-based encoder. The bitstream rewriter changes at least some of the units of encoded video data so as to produce a scalable bitstream with temporal scalability. In doing so, the bitstream rewriter can associate an original sequence parameter set (SPS) and original picture parameter set (PPS) with pictures for a temporal base layer, and associate a new SPS and new PPS with pictures for a temporal enhancement layer. The bitstream rewriter can also alter syntax elements in the units of encoded video data, for example, changing syntax elements in a slice header in ways that avoid bit shifting operations for following coded slice data for a unit of encoded video data for the temporal enhancement layer.

Abstract: Quantization matrices facilitate digital audio encoding and decoding. An audio encoder generates and compresses quantization matrices; an audio decoder decompresses and applies the quantization matrices. The invention includes several techniques and tools, which can be used in combination or separately. For example, the audio encoder can generate quantization matrices from critical band patterns for blocks of audio data. The encoder can compute the quantization matrices directly from the critical band patterns, which can be computed from the same audio data that is being compressed. The audio encoder/decoder can use different modes for generating/applying quantization matrices depending on the coding channel mode of multi-channel audio data. The audio encoder/decoder can use different compression/decompression modes for the quantization matrices, including a parametric compression/decompression mode.

Abstract: Innovations described herein provide a generic encoding and decoding framework that includes some features of simulcast and some features of scalable video coding. For example, a bitstream multiplexer multiplexes component bitstreams into a multi-layer encoding (MLE) bitstream that provides temporal scalability, spatial resolution scalability and/or signal to noise ratio scalability. Each of the component bitstreams provides an alternative version of input video, and a given component bitstream can be a non-scalable bitstream or scalable bitstream. The multiplexer follows composition rules for the MLE bitstream and may rewrite values of certain syntax elements of component bitstreams using an approach that avoids bit shifting operations. A corresponding demultiplexer receives an MLE bitstream that includes component bitstreams and demultiplexes at least part of at least one of the component bitstreams from the MLE bitstream, following decomposition rules for the demultiplexing.

Abstract: Techniques for dynamic switching in coded bitstreams are described. An apparatus may comprise a switching component operative to determine a timepoint to switch from broadcasting a first video stream to broadcasting a second video stream, the first video stream a first encoding of a video source at a first quality level and the second video stream a second encoding of the video source at a second quality level. Other embodiments are described and claimed.

Abstract: Video conference rate matching may be provided. A video conference server may receive video source streams from clients on a video conference. The server may analyze each client's capabilities and choose a video stream to send to each client based on those capabilities. For example, a client capable of encoding and decoding a high definition video stream may provide three source video streams—a high definition stream, a medium resolution stream, and a low resolution stream. The server may send only the low resolution stream to a client with a low amount of available bandwidth. The server may send the medium resolution stream to another client with sufficient bandwidth for the high definition stream, but which lacks the ability to decode the high definition stream.

Abstract: Techniques adaptive rounding offset in video encoding are described. An apparatus may comprise a rounding offset adaptation component operative to adjust a quantization parameter rounding factor for a current macroblock of a current frame of a video stream being compressed by a video encoding system. Other embodiments are described and claimed.

Abstract: Quality settings established by an encoder are adjusted based on information associated with regions of interest (“ROIs”). For example, quantization step sizes can be reduced (to improve quality) or increased (to reduce bit rate). ROIs can be identified and quality settings can be adjusted based on input received from a user interface. An overlap setting can be determined for a portion of a picture that corresponds to an ROI overlap area. For example, an overlap setting is chosen from step sizes corresponding to a first overlapping ROI and a second overlapping ROI, or from relative reductions in step size corresponding to the first ROI and the second ROI. ROIs can be parameterized by information (e.g., using data structures) that indicates spatial dimensions of the ROIs and quality adjustment information (e.g., dead zone information, step size information, and quantization mode information).

Abstract: The coded block parameters used to code blocks of image samples into structures called macroblocks are compressed more efficiently by exploiting the correlation between chrominance and luminance blocks in each macroblock. In particular, the coded block pattern for chrominance and luminance are combined into a single parameter for the macroblock and jointly coded with a single variable length code. To further enhance coding efficiency, the spatial coherence of coded block patterns can be exploited by using spatial prediction to compute predicted values for coded block pattern parameters.

Abstract: Quality settings established by an encoder are adjusted based on information associated with regions of interest (“ROIs”). For example, quantization step sizes can be reduced (to improve quality) or increased (to reduce bit rate). ROIs can be identified and quality settings can be adjusted based on input received from a user interface. An overlap setting can be determined for a portion of a picture that corresponds to an ROI overlap area. For example, an overlap setting is chosen from step sizes corresponding to a first overlapping ROI and a second overlapping ROI, or from relative reductions in step size corresponding to the first ROI and the second ROI. ROIs can be parameterized by information (e.g., using data structures) that indicates spatial dimensions of the ROIs and quality adjustment information (e.g., dead zone information, step size information, and quantization mode information).

Abstract: A video codec efficiently signals that a frame is identical to its reference frame, such that separate coding of its picture content is skipped. Information that a frame is skipped is represented jointly in a coding table of a frame coding type element for bit rate efficiency in signaling. Further, the video codec signals the picture type (e.g., progressive or interlaced) of skipped frames, which permits different repeat padding methods to be applied according to the picture type.