Abstract: Data representing a compressed document, referred to as a smart document, is produced from a document page composed of an array of pixel signals having values representative of gray scale. The system initially subdivides the pixel signals of the document page into a matrix of blocks, and classifies blocks as active or non-active. The document page is segmented into macroblocks (segments) by grouping one or more adjacent active blocks. One or more regions of adjacent non-active blocks are then located and the prevalent value of pixel signals in each region is determined to provide background data. The macroblocks are classified as first or second macroblock types based upon the values of the pixel signals in each macroblock. A bit-map is produced representing the blocks in the matrix of the first macroblock type. The pixel signals in the blocks represented in the map are thresholded into a binary representation to provide a binary image.

Abstract: Synchronization of MPEG audio and video presentations is attained by detecting a lack of synchrony between the data presentations and modifying the audio data stream based on the detected lack of synchrony. Synchrony of the MPEG audio and video presentations is monitored by tracking the amount of data transferred to audio and video interfaces over time. Synchronization of MPEG audio and video presentations is achieved in a system in which audio and video interfaces are controlled by separate and independent timing signal generators by tracking the amount of audio and video data output by the respective audio and video interfaces. The amount of audio and video data output by the interfaces is compared and, as a result of the comparison, the audio data stream is modified to restore synchrony. Alternatively, presentation of the video data stream is modified to achieve synchrony.

Abstract: A four-buffer MPEG decoder is provided for decoding MPEG video frames. A four-buffer frame controller and control method manage the four frame buffers including decoding, displaying and discarding of I-frames, P-frames and B-frames so that video data decoding is accelerated. The four-buffer frame controller and control method frees one frame buffer when the frame buffer contains obsolete data, defined as data which is no longer useful for decoding additional frames and for which storage is not necessary for displaying pictures in a correct temporal order. One example of an obsolete frame is a B-frame that is displayed. Another example is a P-frame for I-frame which is no longer used for motion compensation and has been displayed.