Image analysis – Image compression or coding – Interframe coding
Reexamination Certificate
2000-04-12
2004-01-06
Couso, Jose L. (Department: 2721)
Image analysis
Image compression or coding
Interframe coding
Reexamination Certificate
active
06674909
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a moving picture coding experts group (MPEG) data processing apparatus for processing MPEG video data at a high speed.
As is well known in the art, MPEG is a picture information compressive coding technique for a digital video signal. MPEG codes the digital video signal into a coded digital video signal which is called MPEG video data. The MPEG video data are classified into three types, namely, intra coded picture data, predictive coded picture data, and bidirectionally predictive picture data. Each of the intra coded picture data indicates an intra coded picture which is called an I-picture for short. Each of the predictive coded picture data indicates a predictive coded picture which is called a P-picture for short. Each of the bidirectionally predictive picture data indicates a bidirectionally predictive picture which is called a B-picture for short.
The I-picture datum is generated without use of interframe prediction. The P-picture datum is generated by carrying out prediction on a previous I-picture datum or a previous P-picture datum. The B-picture datum is generated by carrying out prediction on, two fore and aft picture data each of which is the I-picture datum or the P-picture datum.
In picture reproduction, in a case of carrying out a fast feed or the like, in order to processing the MPEG video data at a high-speed, a method comprising the steps of decoding only the I-picture data and the P-picture data and of skipping the B-picture data is used.
In the above-mentioned case, it is desirable to shorten a processing time as far as possible. However, intervals between the I-picture data or the P-picture data are not constant in the MPEG video data because information compressive rates for respective frames are different from each other. As a result, a conventional MPEG data processing apparatus sequentially reads all of the MPEG video data in order to skip the B-picture data even a case where only the I-picture data or the P-picture data are necessitated in the manner which will later become clear.
In addition, various preceding arts related to the present invention are already known. By way of example, UK Patent Publication No. GB 2308264 discloses an MPEG video disk recording system for high-speed reproduction. According to GB 2308264,a disk for high-speed reproduction contains position information of successive I-pictures in a recording area of a present I-picture. Using the above disk, a predetermined waiting time is set in a timer based on a selected multiple speed when moving image data is reproduced at high speed. Referring to the position information of the I-pictures read from the disk, a pickup is moved to the position of the following I-picture to then be reproduced. The data is reproduced at the moved position if the waiting time given by the timer is reached. A larger amount of image information is used within a given time according to each selected multiple speed in order to realize a high-speed reproduction operation with a more natural image displayed.
Japanese Unexamined Patent Publication of Tokkai No. Hei 9-200,695 or JP-A 9-200695 discloses a method and apparatus for decoding video data for high-speed reproduction. According to JP-A 9-200695, picture size items are set in user data in a picture to restrict a coded size of the picture in question. Inasmuch as I-pictures, P-pictures, and B-pictures in MPEG video data are coded in variable length, the coded size of the picture is extremely variable in accordance with complexity of the picture, brightness, and correlation relationship between fore and aft pictures. By doing such as this, although all of data are not searched for a picture start point of a following picture by reading all of data and by comparing picture-start-codes, the coded size of the picture is recognized, it is possible to rapidly shift to the start point of the fore and aft pictures, and it is possible to skip picture data.
Japanese Unexamined Patent Publication of Tokkai No. Hei 10-66,021 or JP-A 10-66021 discloses “METHOD FOR RECORDING COMPRESSED PICTURE DATA”, to effectively execute specific reproduction such as high speed reproduction without increasing the recording data volume by dividing digital compressed picture data into a plurality of areas in accordance with a picture sort, recording the divided data in a recording medium and selectively reproducing data in each area. According to JP-A 10-66021, an area division block divides generated digital compressed picture data into an area including I pictures and an area including P and B pictures and records the divided data in a recording medium through a record processing block. The digital compressed picture data recorded in the medium are read out by a reading processing block, extended by an extending processing block and D/A converted by a D/A conversion circuit and the analog data are outputted as a reproduced signal. In this case, high speed reproduction such as quick feeding, reverse rotation and index reproduction can be attained by continuously reading out only I pictures in one area.
Japanese Unexamined Patent Publication of Tokkai No. Hei 10-42,255 or JP-A 10-42255 discloses “MOVING PICTURE RECORDING DEVICE, RECORDING MEDIUM AND MOVING PICTURE REPRODUCING DEVICE” to efficiently reproduce only a specified frame by detecting a specified frame from an encoded picture data string and recording the position of the detected frame on a recording medium. According to JP-A 10-42255, a reference frame detection circuit retrieves the position of a header code showing the start of a reference frame arranged in the inputted data string. A table generation circuit generates a reference table indicating a positional relationship in the data string of the reference frame based on the start position of the reference frame which is detected in the reference frame detection circuit. A recording conversion circuit converts an input data string and recording conversion circuit the reference table into forms where they can be recorded in the recording medium. A recording control circuit executes control required for the recording of the recording medium. When reference frame information recorded in the table is referred to and data is skipped and reproduced at the reproduction, high speed reproduction is possible. When data is skipped and reproduced by skipping one piece, the two-fold reproduction of high speed reproduction is possible.
Japanese Patent Publication No. 2773594 or JP-B 2773594 discloses “METHOD FOR REPRODUCING FAST FEED PICTURE AND FAST RETURNED PICTURE FROM MOTION PICTURE INFORMATION SUBJECT TO HIGH EFFICIENCY CODING” to obtain a reproduced picture with a smooth motion from motion picture information subject to high efficiency coding at the timer of reproduction of fast feed picture and fast returned picture. According to JP-B 2773594, when a picture of only I frame is selected and reproduced from a bit stream in which I, P, B frames or the like are in existence in mixture and a fast feed/fast returned picture is reproduced, the average interval between I mutual frames arranged in the bit stream is arranged so as to be a predetermined interval by which an interval of displayed pictures is made constant, and the retrieval of an I frame to be reproduced succeedingly to the reproduced I frame is started from a position resulting from subtracting a predetermined value K from an integer multiple of the predetermined interval in the case of reproduction of a fast feed picture and the retrieval of an I frame to be reproduced succeedingly to the reproduced I frame is started from a position resulting from adding a predetermined value M to an integer multiple of the predetermined interval in the case of reproduction of a fast returned picture. Thus, a time required to detect an object I frame is reduced, number of reproduced pictures per unit time is increased and a reproduced picture with smooth motion is easily obtained.
Although the above-mentioned publications are related to this invention, each of the above-mentioned p
Couso Jose L.
Dickstein Shapiro Morin & Oshinsky LLP.
NEC Corporation
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