Abstract: Digital video signals are adaptively compressed for communication to a receiver. A plurality of block-matching motion compensators, each using a different block size, compare current video image data to prior video image data. Video image data output from the motion compensators is compressed, and the compressed data from each motion compensator is compared to find which motion compensator results in the least amount of compressed data for a region of a current video image corresponding to the smallest of the block sizes. The compressed data having the lowest bit count is transmitted to a receiver for recovery of a motion vector. The recovered motion vector is used to recover current video image data from the transmitted data and previously received video image data.

Abstract: Apparatus is provided for decoding variable length code words to recover transform coefficients, such as DCT transform coefficients provided by a high definition television encoder. A first category of the code words has a length of no more than n bits. A second category has a length of greater than n bits. A feedback ROM is used to decode the code words. Code words from the first category are processed by directly addressing a lookup table in the ROM. Code words from the second category are processed using multiple passes through the ROM, wherein a portion of the data output during a prior pass is fed back to address the memory during a subsequent pass.

Abstract: A multichannel image compression system uses a plurality of encoders to compress image data. A coding level command is provided to each of the encoders to specify a level of quality to be provided by each encoder. Encoded image data, provided by the encoders in response to the coding level command, is multiplexed into a combined signal for transmission. The coding level command is adjusted in response to an accumulated amount of data from the combined signal, to maintain the accumulated data within a throughput capability of a communication channel. Although the coding level command may specify a global coding level that is the same for all of the encoders, the encoders can derive local coding levels from the global coding level to provide different encoding qualities. Decoder apparatus is provided to recover an image from the compressed image data.

Abstract: Digital video signals are processed by a plurality of independently operating processors to provide data for transmission in a compressed, motion compensated form. A video image frame area is divided into a set of subframes. The set of subframes is systematically shifted such that the individual subframes progressively cycle across and wrap around the video image frame area. For each successive video frame, video image data bounded by each of the different subframes is independently compressed using motion estimation to reduce data redundancy among the successive frames. The motion estimation is limited for each subframe of a current video frame to areas of a previous video frame that were bounded by the same subframe in the previous frame. In an illustrated embodiment, the set of subframes is shifted once for each successive video frame, and each subframe includes a refresh region whereby the video image frame area is progressively refreshed as the subframes are shifted thereacross.

Abstract: Motion compensated coding of interlaced digital video signals is provided. Pixel data from successive interlaced video fields is compared to similarly situated pixel data in a plurality of previous fields to find a preferred counterpart for each current field set of pixel data. A prediction error signal is generated for each current field set of pixel data indicative of the difference between it and its preferred counterpart from a previous field. Each prediction error signal is encoded with data indicative of the previous field in which the preferred counterpart can be found. In a preferred embodiment, each set of current field pixel data is compared to a range of similarly situated pixels in each of the previous fields, and the prediction error signal is also encoded with motion vector data indicative of the location of the preferred counterpart in its previous field.

Abstract: The compression of successive blocks of digital data is optimized by selecting between different compression algorithms or different data formats on a block-by-block basis. In one application, digitized interlaced video signals are processed for transmission in a compressed form. A set of pixel data presented in a field format is compressed to provide a first compressed video signal. The set of pixel data is also presented in a frame format and compressed to provide a second compressed video signal. Errors are evaluated in the first and second compressed video signals. The compressed video signal having the least error is selected for further processing. The technique is repeated for successive sets of pixel data and the selected signals are encoded to identify them as field formatted or frame formatted signals. The encoded selected signals are then combined to provide a compressed video signal data stream for transmission. Apparatus for receiving and decoding the signals is also disclosed.

Abstract: A method and apparatus are provided for processing digital video signals for transmission in a compressed form. A set of pixel data is compressed without motion compensation to provide a first compressed video signal. The pixel data is compressed using motion compensation to provide a second compressed video signal. The data in the first and second compressed video signals is quantified. A comparison is made to determine which of the signals contains the least data. Successive sets of pixel data are sequentially compressed and quantified and the compressed video signal having the least data for each particular set is selected. The selected signals are encoded to identify them as motion compensated or non-motion compensated signals, and combined to provide a compressed video signal data stream for transmission. Apparatus for receiving and decoding the signals is also disclosed.

Abstract: A wide-aspect-ratio television signal is encoded for transmission within a standard-television-signal-compatible format is encoded by dividing the television signal into center-panel segments from which the horizontally central portion of a television picture produced from said wide-aspect-ratio television signal is displayed in accordance with a standard-television-signal aspect ratio, and side panel segments from which the left and right side portions of the television picture produced from said wide-aspect-ratio television signal are displayed in accordance with the wide aspect ratio; arranging the center panel segments for transmission in the standard-television-signal-compatible format; reducing the spatial frequency extent of at least a portion of said side-panel segments by vertically expanding said portion; and inserting said vertically expanded portion of the side-panel segments for transmission during transmission of said center-panel segments in a manner that enables said inserted portion of the si

Abstract: An image area is refreshed during the transmission of a set of motion compensated sequential video images. The video images are divided into a plurality of adjacent regions. The image area is refreshed during a refresh cycle by communicating a different region in each successive video image of the set without motion compensation. Motion compensation of the previously refreshed regions of the image area during the refresh cycle is restricted to an area containing only the previously refreshed regions. Video image data from a current region being refreshed is encoded for use by a decoder in identifying it as non-motion compensated data.

Abstract: A system for determining the sequential position of video fields of a received video signal that was derived from a film having successive image frames in accordance with the 3:2 pulldown method, wherein the video fields are produced at a greater rate than the film frame rate and in a predetermined repetitive sequentially varying relationship to the film frames wherein at predetermined positions in the sequence a video field is identical to the video field that preceded it by the duration of two video fields. The system includes means for delaying each field of the received video signal; means for comparing each received video field with a video field that has been delayed by the duration of two video fields; and means for comparing the results of a successive number of said comparisons with the predetermined sequence to determine when identical fields are located in only said predetermined positions in a sequence of the compared received video fields.

Abstract: A system for providing a progressive-scan video display signal from a received video signal derived from a film having successive image frames by producing odd and even video fields from each film frame, with the video fields being produced at a greater rate than the film frame rate and in a repetitive sequentially varying relationship to the film frames. The system includes one-field delay devices for delaying each field of the received video signal; and a switching circuit and one-line FIFO stacks for combining the received and delayed video fields to provide a progressive-scan video frame signal at the video field rate, in which alternate lines are derived respectively from odd and even video fields.

Abstract: A book marker is formed of an elongated relatively stiff member. Clips or hooks are formed at the opposite ends of the member and an elastic segment is provided along the length of the member so that the book marker ends can be engaged around opposite edges of a book page with the elastic segment retracting said ends toward one another so as to positively clamp the book marker to the book page.