Abstract: Ways to mitigate loss in inter-operability scenarios for digital video are presented. For example, a bitstream modification tool (such as a bitstream rewriter running on a network node of a videoconferencing system) receives an incoming bitstream of encoded video (e.g., from an encoder that uses a first loss recovery strategy). The bitstream modification tool processes the incoming bitstream of encoded video to produce an outgoing bitstream of encoded video. In doing so, the bitstream modification tool changes at least one syntax element between the incoming bitstream and the outgoing bitstream so as to mitigate picture loss effects during decoding of the outgoing bitstream under lossy delivery conditions. The bitstream modification tool outputs the outgoing bitstream. In this way, the bitstream modification tool can help avoid blank screens, frozen screens, or other failures during decoding under lossy delivery conditions (e.g., with a decoder that uses a different loss recovery strategy).

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: Techniques and tools for video coding/decoding with motion resolution switching and sub-block transform coding/decoding are described. For example, a video encoder adaptively switches the resolution of motion estimation and compensation between quarter-pixel and half-pixel resolutions; a corresponding video decoder adaptively switches the resolution of motion compensation between quarter-pixel and half-pixel resolutions. For sub-block transform sizes, for example, a video encoder adaptively switches between 8x8, 8x4, and 4x8 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.

Abstract: The computational complexity of video encoding is reduced by selectively skipping certain evaluation stages when deciding whether to use inter-picture prediction or intra-picture prediction for a unit of a picture. For example, a video encoder receives a current picture of a video sequence and encodes the current picture. As part of the encoding, for a current unit (e.g., coding unit, macroblock) of the current picture, the encoder can skip time-consuming evaluation of intra-picture prediction modes for blocks of the current unit in situations in which motion compensation for the current unit is already expected to provide effective rate-distortion performance, and use of intra-picture prediction is unlikely to improve performance. In particular, evaluation of the intra-picture prediction modes for blocks of the current unit can be skipped when the current unit has little or no movement and intra-picture prediction has not been promising for the collocated unit in the previous picture.

Abstract: Innovations are presented that reduce the computational complexity of video encoding by selectively skipping certain evaluation stages during intra-picture prediction. A video encoder receives and encodes a current picture. As part of the encoding, for a current block of the current picture, the video encoder evaluates at least some intra-picture prediction modes (“IPPMs”). According to a search strategy, the video encoder selectively skips time-consuming evaluation of certain IPPMs for the current block when those IPPMs are not expected to improve rate-distortion performance, which can dramatically speed up the encoding process. For example, the video encoder conditionally performs a gradient search among angular IPPMs. Or, as another example, the video encoder selectively skips evaluation of IPPMs depending on a cost of encoding the current block using motion compensation. Or, as another example, the video encoder prioritizes IPPMs evaluated for a block of chroma sample values.

Abstract: Systems and methods for multi-layered rate control for scalable video coding. A parameter value may be calculated based on a current layer target bit rate and a current layer buffer state for a frame in a video stream. The frame may include a lower layer and one or more higher layers. A determination may then be made as to whether the current layer is the lower layer. If the current layer is the lower layer, a determination may then be made as to whether a coupling request has been received from a higher layer in the frame. If the coupling request has been received from the higher layer in the frame, the parameter value for the current layer may be increased based on a buffer state threshold value of the higher layer in the frame.

Abstract: Ways to mitigate loss in inter-operability scenarios for digital video are presented. For example, a bitstream modification tool (such as a bitstream rewriter running on a network node of a videoconferencing system) receives an incoming bitstream of encoded video (e.g., from an encoder that uses a first loss recovery strategy). The bitstream modification tool processes the incoming bitstream of encoded video to produce an outgoing bitstream of encoded video. In doing so, the bitstream modification tool changes at least one syntax element between the incoming bitstream and the outgoing bitstream so as to mitigate picture loss effects during decoding of the outgoing bitstream under lossy delivery conditions. The bitstream modification tool outputs the outgoing bitstream. In this way, the bitstream modification tool can help avoid blank screens, frozen screens, or other failures during decoding under lossy delivery conditions (e.g., with a decoder that uses a different loss recovery strategy).

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: Techniques and tools for video coding/decoding with motion resolution switching and sub-block transform coding/decoding are described. For example, a video encoder adaptively switches the resolution of motion estimation and compensation between quarter-pixel and half-pixel resolutions; a corresponding video decoder adaptively switches the resolution of motion compensation between quarter-pixel and half-pixel resolutions. For sub-block transform sizes, 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.

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: 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: A user device within a communication architecture, the user device comprising: an image capture device configured to determine image data for the creation of a video channel defining the shared scene; an intrinsic/extrinsic data determiner configured to determine intrinsic/extrinsic capture device data associated with the image capture device; and a video encoder configured to encode the image data and intrinsic/extrinsic capture device data within the video channel.

Abstract: The detailed description presents innovations in performing motion estimation during digital video media encoding. In one example embodiment, motion estimation is performed using a lower-complexity sub-pixel interpolation filter configured to compute sub-pixel values for two or more candidate prediction regions at a sub-pixel offset, the two or more candidate prediction regions being located in one or more reference frames. For a selected one of the candidate prediction regions at the sub-pixel offset, motion compensation is performed using a higher-complexity sub-pixel interpolation filter.

Abstract: The invention includes several techniques and tools, which can be used in combination or separately. For example, an audio encoder can encode information directly using coding processes that include a windowed overlapped transform, a selective multi-channel transform, scalar quantization and entropy encoding. The audio encoder can also encode information parametrically according to a parametric compression mode that accounts for audibility of distortion according to an auditory model. A corresponding audio decoder can decode first information directly and second information according to the parametric decompression mode.

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: 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: 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: A LED drive circuit according to the present invention comprises a controller and a programmable signal. The controller generates a switching signal coupled to switch a magnetic device for generating an output current to drive a plurality of LEDs. The programmable signal is coupled to regulate a current-control signal of the controller. The switching signal is modulated in response to the current-control signal for regulating the output current, and the level of the output current is correlated to the current-control signal.

Abstract: A dockable device and a power method thereof are provided. The dockable device includes a main device, a main device battery, a connecter, a switch and a voltage down-converter. The connecter may be coupled to a docking device. The switch, coupled to the main device battery, is configured to be closed to provide power to the main device from the main device battery. The voltage down-converter is configured to provide power with a backup voltage to the main device, wherein the backup voltage is less than a discharge voltage output by a fully discharged main device battery.

Abstract: Approaches to selection of motion vector (“MV”) precision during video encoding are presented. These approaches can facilitate compression that is effective in terms of rate-distortion performance and/or computational efficiency. For example, a video encoder determines an MV precision for a unit of video from among multiple MV precisions, which include one or more fractional-sample MV precisions and integer-sample MV precision. The video encoder can identify a set of MV values having a fractional-sample MV precision, then select the MV precision for the unit based at least in part on prevalence of MV values (within the set) having a fractional part of zero. Or, the video encoder can perform rate-distortion analysis, where the rate-distortion analysis is biased towards the integer-sample MV precision. Or, the video encoder can collect information about the video and select the MV precision for the unit based at least in part on the collected information.