摘要:
Methods and apparatus for performing near lossless-concatenated N-level constrained quantization Hadamard transform decoding are provided. Accordingly, the present invention provides a transform-based coding technique, where the coding loss introduced during repeated encoding and decoding is reduced to a substantially insignificant level. This is accomplished by employing a constrained quantization and inverse quantization operation in each level of encoding/decoding in the decoder. In this manner, the concatenation error between each level of a decoder is reduced to a substantially minimum level and the quantization error introduced during quantization operations, i.e., originally at the encoder and in each level of the decoder, is substantially reduced. Thus, the decoded bit stream that is output at the N-th level of the decoder is substantially the same as the original bit stream provided to the input of the encoder.
摘要:
Systems and methods of video conferencing, in which existing video encoders associated with a multipoint control unit (MCU) can be shared among conference participant devices, depending upon the availability of processor and/or memory resources for the MCU. In making decisions regarding the sharing of video encoders, the systems and methods take into account various parameters associated with potential conference participant devices and the total cost of the processor/memory resources for the MCU, to determine whether a video encoder of the MCU can be shared with, or allocated to, the respective conference participant devices. By determining whether to share or allocate a video encoder of the MCU, depending upon the available processor/memory resources for the MCU, the MCU can be made to operate with increased stability. The systems and methods can be applied to any application that sends the same content to multiple receivers, including announcement and video streaming applications.
摘要:
Systems and methods of dynamically adapting multimedia data transmit rates of data senders to available bandwidths of data receivers, in which the available bandwidths are estimated by the data senders using at least reception quality feedback information provided in real-time transport control protocol (RTCP) report packets. The data senders can obtain several bandwidth estimation parameters, such as a packet loss ratio and a round trip delay, from the reception quality feedback information, as well as multimedia data transmit rates from the data senders to the data receivers, and obtain estimates of the available bandwidths of the data receivers using at least the bandwidth estimation parameters and multimedia data transmit rates. Further, using the estimated available bandwidth, the data senders can dynamically adapt the multimedia data transmit rates to the available bandwidths for more reliably achieving the quality of experience (QoE) desired and/or required for multimedia data transmissions.
摘要:
Systems and methods that employ an application-assisted approach to adaptive spatio-temporal error concealment in video decoders. The systems and methods employ a video receiver that can receive real-time video frames from a video transmitter over a wired and/or wireless network. The video receiver includes an end system configurable as an application for consuming the content of the real-time video frames. The end system application can determine whether each received real-time video frame is complete or incomplete, whether each received slice is complete or incomplete, and provide such information to the video decoder for use in avoiding errors while decoding the respective real-time video frames. The video decoder can determine whether any pixel blocks included in real-time video packets are properly decoded or missing, generate statistics regarding the coding mode of the respective pixel blocks, and use such further information while performing adaptive spatio-temporal error concealment on the respective pixel blocks.
摘要:
Provided are methods and systems for rate-distortion optimized quantization and for skipping transform blocks that can take into account the rate-distortion tradeoff as well as the perceptual quality of reconstructed video.
摘要:
A system and method to convert a CIF compressed video to a QCIF video bitstream provides compatibility between the various digital video sources and application uses. A coding mode and a motion vector for a macroblock in a QCIF video sequence are selected from those of a corresponding CIF video sequence without motion estimation.
摘要:
A method of perceptually quantizing a block of an image or video sequence includes generating a non-perceptibility of distortion value. The non-perceptibility of distortion value is calculated from one or more masking values, e.g., complexity, brightness, movement, etc., which themselves are respectively calculated from previously reconstructed samples associated with the image or video sequence. The reconstructed samples form one or more causal templates that are used to calculate such masking effects and, thus, the non-perceptibility of distortion value. The perceptual quantization method then includes generating a quantization step size value which is a function of the non-perceptibility of distortion value. Since templates consisting only of previously reconstructed samples are used to derive the quantization step size value, the templates used at the encoder are also available at the decoder. As a result, an encoder does not need to provide quantization-related information to the corresponding decoder since the decoder can get the information using the same causal templates as those used at the encoder.
摘要:
A method of generating a motion vector associated with a current block of a current frame of a video sequence includes searching at least a section of a reference frame to identify previously reconstructed samples from the reference frame that best estimate motion associated with previously reconstructed samples from the current frame associated with the current block. The previously reconstructed samples may form sets of samples. Such sets may be in the form of respective templates. The method then includes computing a motion vector identifying the location of the set of previously reconstructed samples from the reference frame that best estimates the set of previously reconstructed samples from the current frame associated with the current block. It is to be appreciated such a motion estimation technique is performed in both a video encoder and video decoder so that motion vector data does not need to be transmitted from the encoder to the decoder.
摘要:
Systems and methods that employ an application-assisted approach to adaptive spatio-temporal error concealment in video decoders. The systems and methods employ a video receiver that can receive real-time video frames from a video transmitter over a wired and/or wireless network. The video receiver includes an end system configurable as an application for consuming the content of the real-time video frames. The end system application can determine whether each received real-time video frame is complete or incomplete, whether each received slice is complete or incomplete, and provide such information to the video decoder for use in avoiding errors while decoding the respective real-time video frames. The video decoder can determine whether any pixel blocks included in real-time video packets are properly decoded or missing, generate statistics regarding the coding mode of the respective pixel blocks, and use such further information while performing adaptive spatio-temporal error concealment on the respective pixel blocks.
摘要:
Systems and methods of handling packet errors associated with multimedia data received at data receivers from data senders, in which packet error feedback information is provided by the data receivers to the data senders in one or more real-time transport control protocol (RTCP) feedback packets. The data receivers can calculate, determine, or otherwise obtain costs associated with providing specific forms of packet error feedback information in the RTCP feedback packets, and further calculate, determine, or otherwise obtain wait times for handling out-of-order packets, as well as receiving retransmissions of lost packets. By handling packet errors associated with multimedia data while taking into account such costs and wait times, each of which can have an impact on system bandwidth and/or latency, the systems and methods can more reliably achieve the quality of experience (QoE) generally desired and/or required for multimedia data transmissions.