Methods and architecture for indexing and editing compressed video over the world wide web

Abstract

A system and method is provided for editing and parsing compressed digital information. The compressed digital information may include visual information which is edited and parsed in the compressed domain. In a preferred embodiment, the present invention provides a method for detecting moving objects in a compressed digital bitstream which represents a sequence of fields or frames of video information for one or more captured scenes of video.

1 - 18 . (canceled) 
     
     
         19 . A method for masking a region of a compressed frame of digital video information, comprising the steps of:
 a. determining whether said frame to be masked is intra-coded, predictive-coded or bi-directionally predictive-coded;   b. if said frame is intra-coded:
 i. extracting DCT coefficients for all blocks within said frame; 
 ii. examining block n  to determine where in said frame said block is located; 
 iii. setting said DCT coefficients for said block to zero if said block is outside said mask region; 
 iv. applying a DCT cropping algorithm to said DCT coefficients if said block is on the boundary of said mask region; and 
 v. repeating steps (b)(ii)-(b)(iv) for each block in said frame; 
   c. If said frame is predictive-coded or bi-directionally predictive-coded:
 i. examining motion vectors associated with block n  to determine whether they point to blocks outside or on said mask region; 
 ii. reencoding said block if a motion vector points to blocks outside or on said mask region; and 
 iii. repeating steps (c)(i)-(c)(ii) for all blocks in said frame. 
   
     
     
         20 . A method for generating a reduced speed sequence of frames of video information from a sequence of frames of compressed video information, comprising the steps of:
 a. selecting a frame of compressed video information to be repeated;   b. determining whether said frame to be repeated is intra-coded, predictive-coded or bi-directionally predictive-coded;   c. converting said frame into an intra-coded frame if said frame is a predictive-coded or bi-directionally predictive-coded frame;   d. creating duplicate predictive-coded frames; and   e. arranging said determined frame and said duplicate predictive-coded frames into a sequence of compressed frames of video information.   
     
     
         21 . The method of  claim 20 , wherein said reduced speed sequence of frames generates a frozen frame effect. 
     
     
         22 . The method of  claim 20 , further comprising the step of converting said frame into an intra-coded frame if said frame is a predictive-coded or bi-directionally predictive-coded frame. 
     
     
         23 . A system for editing compressed video information over a distributed network, comprising:
 a. a client computer;   b. a network link, coupled to said client computer, for permitting said client computer to search for and locate compressed video information on said distributed network; and   c. means for editing a compressed bitstream of video information over said distributed network.   
     
     
         24 . The system of  claim 21 , wherein said editing means includes means for dissolving an incoming scene of video information which includes a sequence of fields or frame of compressed video information and an outgoing scene of video information which includes a sequence of fields or frame of compressed video information, said dissolving means comprising:
 a. outgoing motion compensation means for applying DCT domain motion compensation to a last frame of said outgoing video scene to obtain DCT coefficients for all blocks of video information which make up said last frame of said outgoing video scene;   b. incoming motion compensation means, for applying DCT domain motion compensation to a first frame of said incoming video scene to obtain the DCT coefficients for all blocks of video information which make up said first frame of said incoming video scene; and   c. dissolve region creating means, coupled to said incoming motion compensation means and to said outgoing motion compensation means, for creating a first frame in a dissolve region from said DCT coefficients of said last outgoing frame and said first incoming frame.   
     
     
         25 . The system of  claim 21 , wherein said editing means includes means for masking a region of a compressed frame of digital video information, said masking means comprising:
 a. means for determining whether said frame to be masked is intra-coded, predictive-coded or bi-directionally predictive-coded;   b. means for processing intra-coded frames including:
 i. means for receiving DCT coefficients and for extracting DCT coefficients for all blocks within said frame; 
 ii. means, coupled to said receiving means, for examining blocks of compressed video information in said frame to determine where in said frame said block is located; 
 iii. means, coupled to said examining means, for setting said DCT coefficients for said block to zero if said block is outside said mask region; and 
 iv. means, coupled to said setting means, for applying a DCT translation algorithm to said DCT coefficients if said block is on the boundary of said mask region; and 
   c. means for processing predictive-coded and bi-directionally predictive-coded frames, including:
 i. means for receiving and examining motion vectors associated with blocks of video information to determine whether they point to blocks outside or on said mask region; and 
 ii. means, coupled to said receiving means, for reencoding said block if a motion vector points to blocks outside or on said mask region. 
   
     
     
         26 . The system of claim  2 , wherein said editing means includes means generating a reduced speed sequence of frames of video information from a sequence of frames of compressed video information, comprising:
 a. selection means for selecting a frame of compressed video information to be repeated;   b. computational means, coupled to said selection means, for determining whether said frame to be repeated is intra-coded, predictive-coded or bi-directionally predictive-coded;   c. frame generating means, coupled to said computational means and to said converting means, for creating duplicate predictive-coded frames; and   d. frame arranging means, coupled to said frame generating means, for arranging said determined frame and said duplicate predictive-coded frames into a sequence of compressed frames of video information.   
     
     
         27 . A method for converting a full resolution compressed domain bitstream into a reduced resolution compressed bitstream, comprising the steps of:
 a. examining a frame of compressed video information from said full resolution bitstream;   b. determining whether said examined frame is intra-coded, predictive-coded or bi-directionally predictive-coded;   c. extracting DCT DC coefficients for said determined frame if said determined frame is intra-coded   d. applying DCT domain inverse motion compensation to said frame to extract DCT DC coefficients if said frame is predictive-coded or bi-directionally predictive-coded; and   e. converting said extracted DCT DC coefficients into DCT DC coefficients for a reduced size intra-coded frame of video.