# US 5,708,473 A · Two stage video film compression method and system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,708,473 A - Document ID: US5708473A - Status: Granted - Kind: A - Application number: 08/298,507 - Filed: 1994-08-30 - Granted: 1998-01-13 - Earliest claimed: 1994-08-30 - Assignees: Hughes Aircraft Company - Inventors: Donald Mead - Web page: https://patentgrep.com/patent/US5708473A ## CPC - H04N 9/8042: {involving data reduction} - H04N 19/00: Methods or arrangements for coding, decoding, compressing or decompressing digital video signals - H04N 19/107: between spatial and temporal predictive coding, e.g. picture refresh - H04N 19/115: Selection of the code volume for a coding unit prior to coding - H04N 19/124: Quantisation - H04N 19/137: Motion inside a coding unit, e.g. average field, frame or block difference - H04N 19/14: Coding unit complexity, e.g. amount of activity or edge presence estimation (H04N19/146 takes precedence) - H04N 19/15: by monitoring actual compressed data size at the memory before deciding storage at the transmission buffer - H04N 19/172: the region being a picture, frame or field - H04N 19/192: the adaptation method, adaptation tool or adaptation type being iterative or recursive - H04N 19/40: using video transcoding, i.e. partial or full decoding of a coded input stream followed by re-encoding of the decoded output stream - H04N 19/46: Embedding additional information in the video signal during the compression process (H04N19/517, H04N19/68, H04N19/70 take precedence) - H04N 19/503: involving temporal prediction (adaptive coding with adaptive selection between spatial and temporal predictive coding H04N19/107; adaptive coding with adaptive selection among a plurality of temporal predictive coding modes H04N19/109) - H04N 19/61: in combination with predictive coding - H04N 19/85: using pre-processing or post-processing specially adapted for video compression - H04N 19/146: Data rate or code amount at the encoder output - H04N 19/30: using hierarchical techniques, e.g. scalability (H04N19/63 takes precedence) - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract Methods and systems for encoding data representative of a sequence of video frames for transmission to a decoder. A motion compensated predictive coder (24) substantially losslessly compresses the data, computes a motion vector, and forms an intermediate coded representation which includes the compressed data and the motion vector. A frame detector (26), which detects frames having a prediction error which exceeds a predetermined threshold, is coupled to the motion compensated predictive coder (24). A digital storage device (22) is coupled to the motion compensated predictive coder (24) and the frame detector (26). The digital storage device (22) stores the intermediate coded representation and stores a representation of the frames having the prediction error which exceeds the predetermined threshold. A lossless decoder (29), coupled to the digital storage device (22), substantially losslessly decodes the intermediate coded representation to form a decoded representation. A recoder (28), which compresses the decoded representation at a compression ratio in dependence upon a selectable bit rate for transmission, is coupled to the digital storage device (22) and the lossless decoder (29). ## Claims ### Claim 1 A system for encoding data representative of a sequence of video frames, the system comprising; a first coder which losslessly compresses the data to form an intermediate coded representation and includes a predictive coder which compresses the data to form the intermediate coded representation; a digital storage device, coupled to the first coder, which stores the intermediate coded representation; a second coder, coupled to the digital storage device, which compresses the stored intermediate coded representation at a selectable compression ratio to form an encoded representation of the data; and a decoder, interposed between the digital storage device and the second coder, which decodes the stored intermediate coded representation for application to the second coder. ### Claim 2 A system for encoding data representative of a sequence of video frames for transmission to a decoder, the system comprising: a motion compensated predictive coder which losslessly compresses the data, the motion compensated predictive coder computing a motion vector and forming an intermediate coded representation which includes the compressed data and the motion vector; a frame detector which detects frames having a prediction error which exceeds a predetermined threshold; a digital storage device, coupled to the motion compensated predictive coder and the frame detector, which stores the intermediate coded representation and stores a representation of the frames having the prediction error which exceeds the predetermined threshold; a lossless decoder, coupled to the digital storage device, which losslessly decodes the intermediate coded representation to form a decoded representation; a recoder, coupled to the digital storage device and the lossless decoder, which compresses the decoded representation at a compression ratio in dependence upon a selectable bit rate for transmission; and a preload coder, coupled to the digital storage device, which transmits encoded data representative of high activity frames during a period of low transmission activity. ### Claim 3 A method of encoding data representative of a sequence of video frames,the method comprising the steps of: losslessly compressing the data by applying the data to a predictive coder to form an intermediate coded representation; storing the intermediate coded representation in a digital storage device; compressing the stored intermediate coded representation at a selectable compression ratio to form an encoded representation of th data; detecting frames having a prediction error which exceeds a predetermined threshold; and storing in said digital storage device a representation which indicates the frames having the prediction error which exceeds the predetermined threshold. ### Claim 4 (depends on 3) The method of claim 3 further comprising the step of transmitting the encoded representation of the data to a corresponding decoder via a communication channel. ### Claim 5 (depends on 3) The method of claim 3 wherein the step of losslessly compressing the data compresses the data at an average compression ratio greater than 1.8. ### Claim 6 (depends on 3) The method of claim 3 wherein the step of losslessly compressing the data includes the step of applying the data to a transform coder with lossless residual. ### Claim 7 (depends on 3) The method of claim 3 wherein the predictive coder is a motion compensated predictive coder. ### Claim 8 (depends on 7) The method of claim 7 further comprising the steps of: computing a motion vector based upon the data; and storing the motion vector. ### Claim 9 A system for encoding data representative of a sequence of video frames, the system comprising: a first coder which losslessly compresses the data to form an intermediate coded representation and includes a predictive coder which compresses the data to form the intermediate coded representation; digital storage device, coupled to the first coder, which stores the intermediate coded representation; a second coder, coupled to the digital storage device, which compresses the stored intermediate coded representation at a selectable compression ratio to form an encoded representation of the data; and a frame detector coupled to the digital storage device which detects frames having a prediction error which exceeds a predetermined threshold, wherein a representation thereof is stored in the digital storage device. ### Claim 10 (depends on 9) The system of claim 9 wherein the first coder compresses the data at an average compression ratio greater than 1.8. ### Claim 11 (depends on 9) The system of claim 9 wherein the encoded representation of the data is transmitted to a corresponding decoder via a communication channel. ### Claim 12 (depends on 11) The system of claim 11 wherein the selectable compression ratio is based upon a selectable bit rate for transmission. ### Claim 13 (depends on 9) The system of claim 9 wherein the predictive coder is a motion compensated predictive coder which compresses the data to form the intermediate coded representation. ### Claim 14 (depends on 13) The system of claim 13 wherein the motion compensated predictive coder includes an entropy coder. ### Claim 15 (depends on 14) The system of claim 14 wherein the entropy coder includes a Huffman coder. ### Claim 16 (depends on 13) The system of claim 13 wherein the motion compensated predictive coder computes a motion vector, and wherein the motion vector is stored in the digital storage device. ### Claim 17 (depends on 16) The system of claim 16 wherein the second coder compresses the stored intermediate coded representation based upon the stored motion vector.