Abstract: According to one aspect of the present invention, a method and apparatus is provided in which input data (e.g., input video data) is encoded in accordance with a first coding standard (e.g., MPEG-4) to generate encoded data. The input data is also encoded based on a reconstruction of the input data to generate encoded side information associated with the input data. The encoded data are transmitted to a destination (e.g., a decoding subsystem) over a first channel and the encoded side information are transmitted to the destination over a second channel. The encoded data and the encoded side information are decoded and combined at the destination to generate output data.

Abstract: Image data encoded in accordance with a block transform coding scheme may be processed by estimating from the encoded image data a discontinuity threshold for detecting artificial edges introduced by the block transform coding scheme. Once the encoded image data is decoded, differences between pairs of pixels disposed along a block boundary of the decoded image may be determined. If the difference between a given pair of pixels is less than the discontinuity threshold, the given pair of pixels may be adjusted to reduce the difference below a visibility threshold, thereby improving the quality of the decoded image by reducing or eliminating blocking artifacts.

Abstract: Multimedia information communicated between a transmitter and a receiver may be transcoded by intercepting the multimedia information within a network communication system. The available transmission rate of the downlink channel may be estimated by, for example, calculating a ratio of the smoothed round trip time of packets communicated to the receiver and a smoothed congestion window associated with the downlink channel. If the transmission rate at which the multimedia information is encoded is greater than the available transmission rate, the multimedia information may be transcoded to conform the multimedia information to the available transmission rate. The transcoded multimedia information may then be transmitted to the receiver over the downlink channel using a transmission timer.

Abstract: Improved data transport and management within a network communication system may be achieved by utilizing a transmit timer incorporated within the sender device and exploiting host-level statistics for a plurality of connections between a sender and receiver. The period of the transmit timer may be periodically adjusted based on a ratio of the smoothed round-trip time and the smoothed congestion window, thereby reducing or eliminating bursty data transmission commonly associated with conventional TCP architectures. For applications having a plurality of connections between a sender and a receiver that share a common channel, such as web applications, the congestion window and smoothed round trip time estimates for all active connections may be used to initialize new connections and allocate bandwidth among existing connections.

Abstract: Method and apparatus for image transmission using arithmetic coding, based on continuous error detection uses a controlled amount of added redundancy. A continuous error detection scheme is provided, wherein there is a trade-off between the amount of added redundancy and the time needed to detect an error once it occurs. Herein, there is no need for the cyclic redundancy check (CRC) to wait until an entire block of data has been received and processed before an error can be detected. The invention can be used to great advantage both in the automatic repeat request (ARQ) and other concatenated coding schemes. Errors in the received bit stream are detected by introducing added redundancy, e.g., a forbidden symbol, in the arithmetic coding operation. The forbidden symbol is never intended to be encoded. The redundancy error causes loss of synchronization, which is used to detect errors. If a forbidden symbol gets decoded, it means that an error has occurred.

Abstract: Optimum bit rates and power levels are determined for subchannels in multicarrier communication systems. A tangent of the rate-power curve has a slope &lgr;. The slope is defined by the quotient difference between high/low power and high/low rate. A particular &lgr; is evaluated to find its corresponding total power followed by an update of &lgr;, in the form of an increase or decrease, to get closer to the optimal solution. Each &lgr; is evaluated to find the optimal operating point for each subchannel on the rate-power curve by summing the power allocated to the subchannels, and comparing the result to the power budget. Look-up tables are stored for individual channels, but similarity between channels permits joint use of look-up tables by multiple channels. The tables are used to determine the rate-power characteristics at each iteration.

Abstract: For encoding signals corresponding to still images or video sequences, respective standards known as JPEG and MPEG have been proposed. These standards are based on digital cosine transform (DCT) compression. For economy of transmission, DCT coefficients may be "thresholded" prior to transmission, by dropping the less significant DCT coefficients. While maintaining JPEG or MPEG compatibility, threshold selection for the DCT coefficients of an image or video frame is based on optimizing for minimum distortion for a specified maximum target coding bit rate or, equivalently, for minimized coding bit rate for a specified maximum allowable distortion constraint. In the selection process, a dynamic programming method is used.

Abstract: In a digital TV broadcast system, an embedded multiresolution scheme implementing joint source/channel coding is employed to offer at least relatively fine and relatively coarse resolution services. The relatively fine resolution service is intended for receivers within a first radius of a TV signal transmitter and the relatively coarse resolution service is intended for receivers between the first radius and a second, longer radius thereof. Video signals broadcast from the transmitter represent individual signal points which are selected from a signal constellation. The latter comprises signal-point groups each including a multiplicity of the signal points. The selected signal points represent video images in the relatively fine resolution, while the signal-point groups from which the selected signal points originate represent the relatively coarse version of the images.

Abstract: Disclosed is a circuit for adding loss to a signal in a loop carrier transmission system. As data is being transmitted, the circuit determines the digital output needed for an appropriate amount of loss for each channel unit at the end user interface.