Abstract:
For encoding of mixed-content images containing palettized and continuous-tone content, continuous tone content regions in the image are detected and separated. Continuous tone content segmentation classifies pixels as continuous tone content by counting a number of unique pixel values within a pixel neighborhood. Pixels whose count exceeds a threshold are classified as continuous tone content. The technique further scans the image for regions of high continuous tone pixel density. The segmented continuous-tone and palettized content can be encoded separately for efficient compression, and then reassembled at decompression.
Abstract:
The present invention relates to regulating the quality and/or bitrate of content within mixed content video when the video is compressed subject to a bitrate constraint. For example, a screen capture encoder encodes palletized content within a frame of screen capture video. Subject to an overall bitrate constraint, the encoder then allocates bits for continuous tone content within the frame. By controlling the allocation of bits used to encode the continuous tone content, the encoder regulates bitrate for the continuous tone content. This in turn can allow the encoder to regulate spatial quality and/or overall temporal quality for the video. In one scenario, for screen capture video encoded to a (relatively) constant overall bitrate, the screen capture encoder reduces the bitrate (and quality) of the continuous tone content, instead spending bits to increase the overall frame rate of the video.
Abstract:
A system and method for correcting errors and losses occurring during a receiver-driven layered multicast (RLM) of real-time media over a heterogeneous packet network such as the Internet. This is accomplished by augmenting RLM with one or more layers of error correction information. This allows each receiver to separately optimize the quality of received audio and video information by subscribing to at least one error correction layer. Ideally, each source layer in a RLM would have one or more multicasted error correction data streams (i.e., layers) associated therewith. Each of the error correction layers would contain information that can be used to replace lost packets from the associated source layer. More than one error correction layer is proposed as some of the error correction packets contained in the data stream needed to replace the packets lost in the associated source stream may themselves be lost in transmission. A preferred process for generating the error correction streams involves the use of a unique adaptation of the Forward Error Correction (FEC) techniques. This process encodes the transmission data using a linear transform which adds redundant elements. The redundancy permits losses to be corrected because any of the original data elements can be derived from any of the encoded elements. Thus, as long as enough of the encoded data elements are received so as to equal the number of the original data elements, it is possible to derive all the original elements.
Abstract:
Methods and apparatus for processing video data that is divided into frames are presented. In one aspect, this relates to a method for processing video data that is divided into frames. The video data includes a current frame, which has an associated current macroblock, and an adjacent frame, which also has an associated macroblock. The method for processing video data involves obtaining an uncompressed current block that is a part of the current macroblock and an adjacent block that is part of the adjacent macroblock, and calculating a distance between the uncompressed current block and the adjacent block. It is determined whether the distance between the uncompressed current block and the adjacent block is acceptable. If the distance is unacceptable, then the motion between the uncompressed current block and the adjacent block is estimated, and the uncompressed current block is adaptively compressed.
Abstract:
“Correction of errors and losses occurring during a receiver-driven layered multicast (RLM) of real-time media over a heterogeneous packet network such as the Internet is accomplished by augmenting RLM with one or more layers of error correction information. Each receiver separately optimizes the quality of received audio and video information by subscribing to at least one error correction layer. Ideally, each source layer in a RLM would have one or more associated multicasted error correction data streams (i.e., layers). Each error correction layer contains information that can be used to replace lost packets from the associated source layer. More than one error correction layer is proposed as some of the error correction packets contained in the data stream needed to replace the packets lost in the associated source stream may themselves be lost in transmission.”
Abstract:
A projection onto convex sets (POCS)-based method for consistent reconstruction of a signal from a subset of quantized coefficients received from an N×K overcomplete transform. By choosing a frame operator F to be the concatenization of two or more K×K invertible transforms, the POCS projections are calculated in RK space using only the K×K transforms and their inverses, rather than the larger RN space using pseudo inverse transforms. Practical reconstructions are enabled based on, for example, wavelet, subband, or lapped transforms of an entire image. In one embodiment, unequal error protection for multiple description source coding is provided. In particular, given a bit-plane representation of the coefficients in an overcomplete representation of the source, one embodiment of the present invention provides coding the most significant bits with the highest redundancy and the least significant bits with the lowest redundancy. In one embodiment, this is accomplished by varying the quantization stepsize for the different coefficients. Then, the available received quantized coefficients are decoded using a method based on alternating projections onto convex sets.
Abstract:
A “Universal Rate Control Mechanism with Parameter Adaptation” (URCMPA) improves real-time communication (RTC) sessions in terms of delay, loss, throughput, and PSNR. The URCMPA automatically learns network characteristics including bottleneck link capacity, inherent queuing delay, inherent packet loss rates, etc., during RTC sessions. The URCMPA uses this information to dynamically adapt rate control parameters in a utility maximization (UM) framework. The URCMPA operates reliable RTC sessions across a wide range and combination of networks near full throughput rates while maintaining low operating congestion levels (e.g., low queuing delay and low packet loss). Examples of networks applicable for use with the URCMPA include, but are not limited to, combinations of mobile broadband (e.g., 3G, 4G, etc.), WiMAX, Wi-Fi hotspots, etc., and physical networks based on cable, fiber, ADSL, etc. The URCMPA can also dynamically adapt operating congestion levels relative to competing TCP flows to maintain fair use of network resources.
Abstract:
In various embodiments, methods and systems are disclosed for integrating a remote presentation protocol with a datagram based transport. In one embodiment, an integrated protocol is configured to support lossless or reduced loss transport based on Retransmission (ARQ) combined with Forward Error Correction (FEC). The protocol involves encoding and decoding of data packets including feedback headers and FEC packets, continuous measurement of RTT, RTO and packet delay, dynamically evaluating loss probability to determine and adjust the ratio of FEC, congestion management based on dynamically detecting increase in packet delay, and fast data transmission rate ramp-up based on detecting a decrease in packet delay.
Abstract:
An encoder performs context-adaptive arithmetic encoding of transform coefficient data. For example, an encoder switches between coding of direct levels of quantized transform coefficient data and run-level coding of run lengths and levels of quantized transform coefficient data. The encoder can determine when to switch between coding modes based on a pre-determined switch point or by counting consecutive coefficients having a predominant value (e.g., zero). A decoder performs corresponding context-adaptive arithmetic decoding.
Abstract:
In various embodiments, methods and systems are disclosed for a hybrid rate plus window based congestion protocol that controls the rate of packet transmission into the network and provides low queuing delay, practically zero packet loss, fair allocation of network resources amongst multiple flows, and full link utilization. In one embodiment, a congestion window may be used to control the maximum number of outstanding bits, a transmission rate may be used to control the rate of packets entering the network (packet pacing), a queuing delay based rate update may be used to control queuing delay within tolerated bounds and minimize packet loss, and aggressive ramp-up/graceful back-off may be used to fully utilize the link capacity and additive-increase, multiplicative-decrease (AIMD) rate control may be used to provide fairness amongst multiple flows.