Pulse or digital communications – Bandwidth reduction or expansion – Television or motion video signal
Reexamination Certificate
2000-02-17
2002-09-17
Britton, Howard (Department: 2613)
Pulse or digital communications
Bandwidth reduction or expansion
Television or motion video signal
C348S699000, C370S466000, C375S240260, C382S243000
Reexamination Certificate
active
06452971
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a moving picture transforming system for transforming a moving picture compress ion format and, more particularly, a moving picture transforming system which is able to reduce an amount of operation to detect motion vectors by reusing or referring to the motion vectors and thus achieve the higher-speed transformation of the moving picture and the reduction of degradation in the picture quality.
In recent years, digitization of the telecommunication technology has been proceeded. A project for digitizing the current analogue broadcasting system such as NTSC/PAL/SECAM, etc. is also in progress. In addition, as the new broadcasting service employing the digital technology, there are the satellite broadcasting which can provide the multi-channel service, the ground wave broadcasting of the Hi-Vision broadcasting (ATV: Advanced Television), the video-on-demand, etc. Meanwhile, as the communication service employing the digital technology, there are the TV phone, the electronic conference system, etc.
However, as the common subject occurred in communicating such moving pictures by the digital signals, it may be considered that a great deal of information are needed. Since such digital signals are reproduced at the high frame rate in real time, the moving picture compression technology is indispensable to suppress the traffic in the network.
In order to compress effectively the moving picture data having an enormous amount of information, an approach which can reduce the redundancy by utilizing the correlation in the time-base axis or the space-base axis is employed. Although there are various compression schemes, there is the scheme using MPEG (Moving Picture Experts Group) as the typical one. This scheme has been discussed in ISO-IEC/JTC1/SC2/WG11 and then proposed as the standard scheme, and the hybrid scheme utilizing motion compensation coding, DCT (Discrete Cosine Transform) coding, and VLC (Variable Length Coding) in combination is adopted.
Further, the technology which is called the transcoding to execute the bit rate transformation under restrictions of the communication media becomes in use. However, in the future, from the viewpoint of reuse of the moving picture contents which have already accumulated and the viewpoint of mutual utilization between the TV phone/the electronic conference system which have already been spread and future mobile moving picture communication, it may be expected that great importance will be attached to the transcoding between different moving picture compression schemes.
A view of a configuration of a typical decoding device based on the MPEG is shown in
FIG. 1. A
view of a configuration of an encoding device based on the MPEG is shown in FIG.
2
. As a typical example of the image transmission utilizing the transcoding technology, a configuration of “Transcoding Method and System” set forth in Patent Application Publication (KOKAI) Hei 8-51631 is shown in FIG.
3
.
A decoder shown in
FIG. 1
comprises a coding channel
12
. This coding channel includes in series a variable length decoding means
1
, an inverse quantizing means
2
, and an inverse frequency converting means (e.g., an inverse orthogonal transforming means such as an inverse discrete cosine transforming means
3
). The decoder comprises further a motion compensation stage
4
in series. This stage includes in series an image memory (MEM)
41
for receiving an output signal from the decoder, a motion compensating means
42
operated based on an output signal of the memory
41
and a (transmitted and/or accumulated) motion vector V which the decoder receives simultaneously with a coded signal, and an adder
43
for adding an output signal of the inverse discrete cosine transforming means
3
and an output signal of the motion compensating means
42
. An output terminal of this adder constitutes both an output terminal of the decoder and an input terminal of the memory
41
.
The encoder shown in
FIG. 2
comprises a coding and decoding channel
13
and a prediction channel
10
. The coding and decoding channel
13
includes in series a frequency converting means (similarly, an orthogonal transforming means such as a discrete cosine transforming means
5
), a quantizing means
6
, and a variable length coding means
7
. Further, an inverse quantizing means
8
and an inverse frequency converting means (e.g., an inverse orthogonal transforming means such as an inverse discrete cosine transforming means
9
) are provided on the output side of the quantizing means
6
. In the following explanation, an output terminal of the variable length coding means
7
is called a prediction output terminal, and constitutes an input terminal of the prediction channel
10
. The prediction channel
10
includes an adder
101
which reconstructs the blocks (in this example, the original video signal which corresponds to the moving picture series is divided into blocks which have the same size as the M×N pixels), an image memory
102
, a motion compensating means
103
operated based on the previously estimated motion vector, and a subtracting means
11
for receiving the input signal of the encoder at its plus input terminal and receiving an output signal of the motion compensating means
103
at its minus input terminal and then coding only a difference between these signals. The adder
101
receives the output signal from the motion compensating means
103
and a prediction output signal from the coding and decoding channel
13
.
The moving picture transforming system shown in
FIG. 3
comprises a variable length coding channel portion
13
at a later stage of a variable length decoding channel portion
12
. A prediction function portion
140
which has an image memory
41
and a motion vector compensating means
42
is connected between these two channels.
The above moving picture transforming system in the prior art intends to achieve the change (mainly the reduction since the picture quality degraded due to compression cannot be increased) of the bit rate (code capacity per unit time: represented by bit/second) of the moving picture simply and at a low cost by changing the moving picture compression degree since the motion prediction is omitted and the motion compensating means is used commonly. The above system has such disadvantages that such system cannot achieve the transformation into the different image compression scheme (especially, transformation into the scheme having the different spatial resolution or temporal resolution) and that, in the case that the spatial resolution and temporal resolution (frame rate) do not have the same format even if the system has the same spatial resolution and temporal resolution, differential image from the prediction image is increased if the motion vectors are used again as they are and thus the degradation of the picture quality is increased to convert into a certain bit rate.
SUMMARY OF THE INVENTION
It is an object of the present invention to achieve the high-speed transformation into a different moving picture compression format with less degradation in the picture quality.
In order to overcome the above subjects, first, the present invention provides a moving picture transforming system which comprises:
a moving picture decoding portion including: a variable length decoding means for receiving coded digital signals of a compressed moving picture and outputting quantized video information and motion information; an inverse quantizing means for reversing quantization of the quantized video information output from the variable length decoding means; an inverse orthogonal transforming means for inversely orthogonal-transforming an output of the inverse quantizing means; a motion compensating means for compensating an image based on the motion information output from the variable length decoding means; an image memory for storing a reference image used by the motion compensating means;
a motion information memory portion for storing the motion information output from the moving pictu
Iwasaki Osamu
Komiya Daisaku
Uenoyama Tsutomu
Britton Howard
Matsushita Electric - Industrial Co., Ltd.
Pearne & Gordon LLP
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