Moving image estimating system

Details Moving image estimating system Moving image estimating system

1998-09-29

2004-08-10

Kelley, Chris (Department: 2613)

Pulse or digital communications

Bandwidth reduction or expansion

Television or motion video signal

Reexamination Certificate

active

06775326

ABSTRACT:

This application is the national phase under 35 U.S.C. §371 of prior PCT International Application No. PCT/JP98/00232 which has an International filing date of Jan. 22, 1998 which designated the United States of America, the entire contents of which are hereby incorporated by reference.
TECHNICAL FIELD
The present invention relates to the prediction of a moving picture implemented, for example, in
a moving picture encoder/decoder used in a portable/stationary video communication device and the like for visual communications in a video telephone system, a video conference system or the like,
a moving picture encoder/decoder used in a picture storage/recording apparatus such as a digital VTR and a video server, and
a moving picture encoding/decoding program implemented in the form of a single software or a firmware as a Digital Signal Processor (DSP).
BACKGROUND ART
MPEG-4 (Moving Picture Experts Group Phase-4) Video Encoding/Decoding Verification Model (hereinafter referred to by the initials VM) whose standardization is in progress by ISO/IEC JTC1/SC29/WG11 may be introduced as a conventional type of predictive encoding/decoding in an encoding/decoding system of moving pictures. The VM continues to revise its contents according to the progress being made in standardization of MPEG-4. Here, Version 5.0 of the VM is designated to represent the VM and will be simply referred to as VM hereinafter.
The VM is a system for encoding/decoding each video object as one unit in view of a moving picture sequence being an aggregate of video objects changing their shapes time-/space-wise arbitrarily.
FIG. 29
shows a VM video data structure. According to the VM, a time-based moving picture object is called a Video Object (VO), and picture data representing each time instance of the VO, as an encoding unit, is called a Video Object Plane (VOP). If the VO is layered in time/space, a special unit called a Video Object Layer (VOL) is provided between the VO and the VOP for representing a layered VO structure. Each VOP includes shape information and texture information to be separated. If the moving picture sequence includes a single VO, then the VOP is equated to a frame. There is no shape information included, in this case, and the texture information alone is then to be encoded/decoded.
The VOP includes alpha data representing the shape information and texture data representing the texture information, as illustrated in FIG.
30
. Each data are defined as an aggregate of blocks (alphablocks/macroblocks), and each block in the aggregate is composed of 16×16 samples. Each alphablock sample is represented in eight bits. A macroblock includes accompanied chrominance signals being associated with 16×16 sample luminance signals. VOP data are obtained from a moving picture sequence externally processed outside of an encoder.
FIG. 31
is a diagram showing the configuration of a VOP encoder decoding according to the VM encoding system. The diagram includes original VOP data P
1
to be inputted, an alphablock P
2
representing the shape information of the VOP, a switch P
3
a
for passing the shape information, if there is any, of the inputted original VOP data, a shape encoder P
4
for compressing and encoding the alphablock, compressed alphablock data P
5
, a locally decoded alphablock P
6
, texture data (a macroblock) P
7
, a motion detector P
8
, a motion parameter P
9
, a motion compensator P
10
, a predicted picture candidate P
11
, a prediction mode selector P
12
, a prediction mode P
13
, a predicted picture P
14
, a prediction error signal P
15
, a texture encoder P
16
, texture encoding information P
17
, a locally decoded prediction error signal P
18
, a locally decoded macroblock P
19
, a sprite memory update unit P
20
, a VOP memory P
21
, a sprite memory P
22
, a variable-length encoder/multiplexer P
23
, a buffer P
24
, and an encoded bitstream P
25
.
FIG. 32
shows a flowchart outlining an operation of the encoder.
Referring to the encoder of
FIG. 31
, the original VOP data P
1
are decomposed into the alphablocks P
2
and the macroblocks P
7
(Steps PS
2
and PS
3
). The alphablocks P
2
and the macroblocks P
7
are transferred to the shape encoder P
4
and the motion detector P
8
, respectively. The shape encoder P
4
is a processing block for data compression of the alphablock P
2
(step PS
4
), the process of which is not discussed here further in detail because the compression method of shape information is not particularly relevant to the present invention.
The shape encoder P
4
outputs the compressed alphablock data P
5
which is transferred to the variable-length encoder/multiplexer P
23
, and the locally decoded alpha data P
6
which is transferred sequentially to the motion detector P
8
, the motion compensator P
10
, the prediction mode selector P
12
, and the texture encoder P
16
.
The motion detector P
8
, upon reception of the macroblock P
7
, detects a local-motion vector on a macroblock basis using reference picture data stored in the VOP memory P
21
and the locally decoded alphablock P
6
(step PS
5
). Here, the motion vector is one example of a motion parameter. The VOP memory P
21
stores the locally decoded picture of a previously encoded VOP. The content of the VOP memory P
21
is sequentially updated with the locally decoded picture of a macroblock whenever the macroblock is encoded. In addition, the motion detector P
8
detects a global warping parameter, upon reception of the full texture data of the original VOP, by using reference picture data stored in the sprite memory P
22
and locally decoded alpha data. The sprite memory P
22
will be discussed later in detail.
The motion compensator P
10
generates the predicted picture candidate P
11
by using the motion parameter P
9
, which is detected in the motion detector P
8
, and the locally decoded alphablock P
6
(step PS
6
). Then, the prediction mode selector P
12
determines the final of the predicted picture P
14
and corresponding prediction mode P
13
of the macroblock by using a prediction error signal power and an original signal power (step PS
7
). In addition, the prediction mode selector P
12
judges the coding type of the data either intra-frame coding or inter-frame coding.
The texture encoder P
16
processes the prediction error signal P
15
or the original macroblock through Discrete Cosine Transformation (DCT) and quantization to obtain a quantized DCT coefficient based upon the prediction mode P
13
. An obtained quantized DCT coefficient is transferred, directly or after prediction, to the variable-length encoder/multiplexer P
23
to be encoded (steps PS
8
and PS
9
). The variable-length encoder/multiplexer P
23
converts the received data into a bitstream and multiplexes the data based upon predetermined syntaxes and variable-length codes (step PS
10
). The quantized DCT coefficient is subject to dequantization and inverse DCT to obtain the locally decoded prediction error signal P
18
, which is added to the predicted picture P
14
, and the locally decoded macroblock P
19
(step PS
11
) is obtained. The locally decoded macroblock P
19
is written into the VOP memory P
21
and the sprite memory P
22
to be used for a later VOP prediction (step PS
12
).
Dominant portions of prediction including a prediction method, a motion compensation, and the update control of the sprite memory P
22
and the VOP memory P
21
will be discussed below in detail.
(1) Prediction Method in the VM
Normally, four different types of VOP encoding shown in
FIG. 33
are processed in the VM. Each encoding type is associated with a prediction type or method marked by a circle on a macroblock basis. With an I-VOP, intra-frame coding is used singly involving no prediction. With a P-VOP, past VOP data can be used for prediction. With a B-VOP, both past and future VOP data can be used for prediction.
All the aforementioned prediction types are motion vector based. On the other hand, with a Sprite-VOP, a sprite memory can be used for prediction. The sprite is a picture space generated through a step-by-step mixi

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