Abstract: Briefly, in accordance with one embodiment of the invention, a method of producing quantization error signal samples for a layer of a multi-layer coder applied to successive video frames includes: processing in the transform domain quantization error signal samples produced by the immediately preceding layer. In this embodiment, processing includes using reference quantization error signal samples if the quantization error for the quantization error signal samples exceeds a predetermined criterion or threshold.

Abstract: A system and method are provided for enabling a user to access a plurality of local wireless computer networks from a mobile computing device, using a single wireless access account to pay for the access charges incurred at the plurality of local wireless computer networks.

Abstract: The present invention discloses a method and apparatus for transmitting a plurality of images of at least over a packet network. A plurality of motion vectors based on at least one moving object is generated. The plurality of images is encoded by constraining the plurality of motion vectors so as to produce a bitstream. The bitstream is then transmitted over the packet network.

Abstract: In a packet-based video environment, video frame data is compressed according to a block-based vide transform algorithm and fragmented into a sequence of packets. One or more packets are appended with transport header information indicating the place in the sequence for each packet. The packets of compressed video frame data are sent over a network or transmission medium to a remote user creating the possibility that one or more of the packets would be lost. When the packets are received, the transport header is checked to determine if any packets are lost. An extended compressed bitstream is created that includes the compressed video frame data from the packets and bitstream information stream data that identifies which of the video frame data are lost and indicating parameters for decompressing the compressed bitstream.

Abstract: A method and apparatus for transmitting a video bitstream over a communication medium is provided. The video bitstream is carried as payload data within packets of a transport protocol by dynamically determining whether to fragment the video bitstream at current macroblock. If no determination of fragmentation occurs, based upon the maximum transfer unit size of the transport protocol, the current macroblock is transmitted in a current transport protocol packet. However, if a determination of fragmentation occurs, synchronization information and the current macroblock are transmitted in another transport protocol packet. Permitting dynamic insertion of synchronization information, gives rise to a flexible video bitstream that can be efficiently packetized for a variety of transport protocols.

Abstract: Image signals are converted from one color format to another using a lookup table based on interleaved indices generated from the components in the first color format. In a preferred embodiment, image signals in a YUV format are converted to image signals in a CLUT format by interleaving bits from the U and V components and appending bits from the Y component. By interleaving the U and V components, cache efficiency is improved when color conversion is implemented on a general-purpose processor with limited on-chip cache.

Abstract: A method and apparatus for performing variable length decoding on a coded bitstream produced by an encoding apparatus is provided. The coded bitstream includes one or more variable length codes (VLCs) produced by a Huffman code. Upon receiving the coded bitstream, for each of the VLCs in the coded bitstream a determination is made as to which of a major table or a minor table contains an entry corresponding to the VLC. The major table has been statistically optimized to contain entries corresponding to frequently used VLCs. The minor table has been optimized for space and contains entries corresponding to VLCs that are less frequently used. The optimized tables provide a more efficient method and apparatus for decoding variable length codes. Specifically, the optimized tables provide a method of variable length decoding that can run efficiently on a target platform having a limited data and code cache.

Abstract: A current level of a virtual transmission buffer is maintained and used to select video frames for compression. The current level is compared to a threshold to determine whether to compress the current frame. The threshold is dynamically maintained between an upper "full" level and a lower "clear" level. If the current level exceeds the full level, the video compression processing is changed to a decline mode in which the threshold is gradually decremented towards the clear level. In addition, if the current level exceeds a "watch" level for too long, then the video compression processing is also switched to the decline mode. The present invention allows the virtual buffer to absorb variability in compressed frame size from frame to frame without resulting in undesired latency.