Patent ID: 8514942

Claim:
A device for extracting low resolution frames from high resolution compressed frames which have been encoded using predictive coding techniques, comprising: a device for generating frequency coefficients of a prediction needed, wherein the number of frequency coefficients are no more than N/2×N/2 and a fraction of the number in high resolution compressed Intra frames being sampled; a device for generating corresponding frequency coefficients of a residual error; a device for reconstructing only those pixels of a particular block that will be used as reference pixels for decoding future blocks; a device for adding the frequency coefficients of the prediction needed to corresponding frequency coefficients of the residual error; a device for taking an inverse transform of the sum of said frequency coefficients of prediction and said frequency coefficients of a reconstructed residual error; a device for normalizing the result of said inverse transform; a device for deciding if a down-sampled frame generated is to be used as a reference frame, then any reference DC coefficients for a next frame are generated by a weighted average of four reference DC coefficients, so the DC coefficient of the reference block of the next frame are within a region covered by the four reference DC coefficients, wherein, using down-sampled Intra frames as reference frames for Intra frame reconstruction introduces drift errors which are accepted; a video thumbnail device for generating a low resolution video bitstream for use as a supplementary video file for a corresponding high-resolution video bitstream; a device for generating supplementary information files to index locations and frame properties of key frames in video bitstreams; a device for associating and storing supplementary video files and supplementary information files along with their corresponding video bitstreams in a single container file format; and a device for extracting selected low-resolution frames from a high-resolution stored compressed video file, wherein frames to be decoded are either chosen on-the-fly from the high-resolution coded bitstream.