Apparatus and method for processing groups of fields in a video data compression system to encode a single frame as an I-field and a P-field

Abstract

A video compression system which is based on the image data compression system developed by the Motion Picture Experts Group (MPEG) uses various group-of-fields configurations to reduce the number of binary bits used to represent an image composed of odd and even fields of video information, where each pair of odd and even fields defines a frame. [According to a first method, each field in the group of fields is predicted using the closest field which has previously been predicted as an anchor field. According to a second method, intra fields (I-fields) and predictive fields (P-fields) are distributed in the sequence so that no two I-fields and/or no two P-fields are at adjacent locations in the sequence. According to a third method, t] The number of I-fields and P-fields in the encoded sequence is reduced by encoding one field in a given frame as a P-field or a B-field where the other field is encoded as an I-field and encoding one field in a further frame as a B-field where the other field is encoded as a P-field.

Description

BACKGROUND OF THE INVENTIONThe present invention concerns video data compression and in particular, apparatus and a method for processing groups of successive fields of video information to obtain high levels of data compression.Image sequence data compression systems such as that proposed by the Moving Pictures Experts Group (MPEG), a committee within the International Standards Organization (ISO), have been very effective in coding image sequences for video signals under the NTSC standard as well as for High Definition Television (HDTV) sources. The MPEG system is described in a paper entitled "MPEG Video Simulation Model Three (SM3)" by the Simulation Model Editorial Group, available from ISO as ISO-IEC / JTC1 / SC2 / WG11 / N0010 MPEG 90 / 041, 1990 which is hereby incorporated by reference for its teachings on the MPEG video signal encoding method.The MPEG system integrates a number of well-known data compression techniques into a single system. These include motion-compensated predictiv...

AI Technical Summary

Benefits of technology

The present invention is embodied in a video encoding system which uses field-oriented motion predictive coding based on data in one or more anchor fields to compress video data. The system includes apparatus which processes groups of fields of video data such that a predicted field is encoded using at least one anchor field which has previously been encoded and which is which closer in time to the predicted field than any other previously encoded field.

Problems solved by technology

In addition, the dependence of one frame on its predecessor I or P-frame limits the ability of the receiver to display a frame selected at random and to accommodate standard television functions such as intra-group scene changes and channel switching.

These limitations could be removed by encoding each frame as an I-frame, however, the resulting coded video signal would need considerably more bits per frame since it would not exploit the temporal redundancy that is inherent in most video information.

It is well known that, due to the temporal separation between successive fields, this method may produce unsatisfactory results.

Motion predictive encoding is a problem with any of the MPEG encoding methods.

This method does not perform well, for example, when the block is part of an object which is rotated about an axis in the image plane or which is subject to a change in size due to motion into or out of the frame or such as would result from an image zoom.

In addition, this encoding method may not work well when there is a relatively large temporal separation between a frame to be predicted and its reference or anchor frame.