Abstract: A method for implementing a video tripwire includes steps of calibrating a sensing device to determine sensing device parameters for use by the system; initializing the system, including entering at least one virtual tripwire; obtaining data from the sensing device; analyzing the data obtained from the sensing device to determine if the at least one virtual tripwire has been crossed; and triggering a response to a virtual tripwire crossing.

Abstract: A method for implementing a video tripwire includes steps of calibrating a sensing device to determine sensing device parameters for use by the system; initializing the system, including entering at least one virtual tripwire; obtaining data from the sensing device; analyzing the data obtained from the sensing device to determine if the at least one virtual tripwire has been crossed; and triggering a response to a virtual tripwire crossing.

Abstract: An algorithm for distributing video buffer rate control over a parallel compression architecture uses parallel processors to first compute complexity measures for each macroblock of a current picture. Based upon the complexity measures a master controller determines target rates for each slice of the current picture. A set of slices are then encoded in parallel by the parallel processors acting as microrate controllers, each slice being encoded based solely upon its own target rate. After the set of slices are encoded, the target rates are adjusted for the remaining slices based upon the actual rates from the encoded slices, and the next set of slices is encoded in parallel based upon the updated target rates. After each macroblock within a slice is encoded, a VBV fullness check is made to detect if VBV overflow or underflow is likely to occur. In such an event emergency action is taken to prevent such overflow or underflow.

Abstract: A 3-2 pulldown detector for a video compression encoder initially converts each frame of an input video signal that includes converted film material as well as original video material into top and bottom fields. Consecutive fields from the top and bottom fields are then input to respective sum of absolute difference circuits, the outputs of which are subtracted from each other to produce a difference signal. The difference signal is processed to remove spikes that represent scene changes and to generate a flag signal during the periods of the input video signal when the converted film material is present. The flag signal is then used by a frame rate reduction circuit to eliminate the repeated fields in the converted film material prior to input to a video encoder that outputs a compressed video signal.

Abstract: Pre-oddification of quantized discrete cosine transform (DCT) coefficients representing video data reduces high frequency noise that accumulates over multiple stages of encoding/decoding due to oddification in the decoders. The quantized DCT coefficients are inverse quantized, and the resulting inverse quantized coefficients are summed. If the sum is even, then the last quantized coefficient ?7,7! is adjusted to reduce high frequency energy accumulation at that coefficient. The last quantized coefficient may be set to zero, or may be incremented/decremented by "1" in the opposite manner than oddification occurs in the decoders. Further the values of a quantization matrix may be set, either manually or automatically as a function of the complexity of the video data, to assure that it is possible for the sum of the inverse quantized coefficients to be odd.

Abstract: An encoder segments frames in a sequence of digital images into multiple regions of arbitrary shape each of which has a corresponding motion vector relative to a previous decoded frame. A hierarchical multi-resolution motion estimation and segmentation technique, which segments the frame into multiple blocks and which assigns a best motion vector to each block is used. Blocks having the same or similar motion vector are then merged to form the arbitrarily-shaped regions. The shape of each region is coded, and a decision is made to code additional image data of each region in one of three modes. In a first inter-frame mode, a motion vector associated with a region is encoded. In a second inter-frame mode, a prediction error for the region is also encoded. In an intra-frame mode, the intensity of each picture element in the region is encoded.

Abstract: The quality of video images received at the remote end of an ATM network capable of transmitting data at high and low priorities is greatly improved at high cell loss levels by employing a two-layered video encoding technique that adapts the method for encoding information transmitted in the low-priority bit-stream to the rate of cell loss on the network so that compression efficiency and image quality are high when the network load is low and resiliency to cell loss is high when the network load is high. The encoder adapts its encoding method in response to a cell loss information signal generated by the remote decoder by selecting the prediction mode used to encode the low-priority bit-stream, and by changing the frequency at which slice-start synchronization codes are placed within the low-priority bit-stream.

Abstract: A novel method and apparatus for use in digital video compression provides improved block-based motion compensation using the global motion of a video frame. A video frame comprising a plurality of blocks may be compressed for transmission using block motion vectors. Motion vectors are generated by block matching a block to be coded with a block within a reference frame and determining the displacement therebetween. To effect block matching, motion compensation techniques define a search window within one or more reference frames within which a displaced block will be found. According to the present invention, the location of the search window within a reference frame is defined using the global motion of the frame.