Multiplex communications – Communication techniques for information carried in plural... – Combining or distributing information via time channels
Reexamination Certificate
1999-03-18
2003-05-20
Jung, Min (Department: 2731)
Multiplex communications
Communication techniques for information carried in plural...
Combining or distributing information via time channels
C370S537000, C370S542000, C370S522000, C345S419000, C345S581000
Reexamination Certificate
active
06567427
ABSTRACT:
TECHNICAL FIELD
The present invention relates to image signal multiplexing apparatus and methods, image signal demultiplexing apparatus and methods, and transmission media, and more particularly to image signal multiplexing apparatus and methods, image signal demultiplexing apparatus and methods, and transmission media which are suitable for use with data that may be recorded on a recording medium such as a magneto-optical disc, a magnetic tape or the like, reproduced from such a recording medium to be displayed on a display, and data transmitted from a transmission side to a reception side through a transmission path for displaying, editing and recording on the reception side such as in a teleconference system, a television telephone system, broadcasting equipment, a multimedia database search system and so on.
BACKGROUND ART
In a system for transmitting a motion picture signal to a remote location, for example, such as a teleconference system, a television telephone system or the like, an image signal is compress-encoded utilizing line correlation and interframe correlation of the image signal in order to efficiently utilize a transmission path.
Also, in recent years, as the processing performance of computers has been improved, a motion picture information terminal using a computer is becoming more and more popular. In such a system, information is transmitted through a transmission path such as a network to a remote location. Similarly, in this case, signals such as image signals, audio signals and data to be transmitted are compress-encoded for transmission in order to efficiently utilize the transmission path.
On a terminal side, a compressed signal transmitted thereto is decoded on the basis of a predetermined method to recover original image signals, audio signals, data and so on which are outputted to a display, a speaker and so on provided in the terminal. In the prior art, a transmitted image signal and so on have been merely outputted to a display device as they are, whereas in a computer-based information terminal, a plurality of such image signals, audio signals and data can be displayed in a two-dimensional or three-dimensional space after they have been transformed. Such processing can be realized by describing information on the two-dimensional and three-dimensional space in a predetermined method on the transmission side, and performing predetermined transform processing, for example, on the image signals to display in accordance with the description on a terminal.
A representative scheme for describing such spatial information is, for example, VRML (Virtual Reality Modelling Language). This has been standardized in ISO-IEC_JTC1/SC24, and its latest version VRML 2.0 is described in ISI4772. The VRML is a language for describing a three-dimensional space, wherein a collection of data is defined for describing attributes, shape and so on of a three-dimensional space. This collection of data is called a node. Describing a three-dimensional space involves describing how these predefined nodes are synthesized. For a node, data indicative of attributes such as color, texture or the like and data indicative of the shape of a polygon are defined.
On a computer-based information terminal, a predetermined object is produced by CG (Computer Graphics) using polygons and so on in accordance with descriptions such as VRML as mentioned above. With the VRML, it is also possible to map a texture to a three-dimensional object composed of thus produced polygons. A node called Texture is defined when a texture to be mapped is a still image, while a node called Movie Texture is defined when a motion picture, where information on the texture to be mapped (the name of a file, display start and end time, and so on) is described in the node.
Here, the mapping of a texture, (hereinafter, called texture mapping as appropriate) will be described with reference to FIG.
14
. First, a texture to be mapped (image signal) and a signal representative of its transparency (Key signal), and three-dimensional object information are inputted from the outside, and stored in a predetermined storage area in a group of memories
151
. The texture is stored in a texture memory
152
; the signal representative of the transparency in a gray scale memory
153
; and the three-dimensional object information in a three-dimensional information memory
154
. Here, the three-dimensional object information refers to information on the shapes of polygons, information on illumination, and so on.
A rendering circuit
155
forms a three-dimensional object using polygons based on the predetermined three-dimensional object information recorded in the group of memories
151
. The rendering circuit
155
reads a predetermined texture and a signal indicative of its transparency from the memory
152
and the memory
153
based on the three-dimensional object information, and maps the texture to the three-dimensional object. The signal representative of the transparency indicates the transparency of the texture at a corresponding location, and therefore indicates the transparency of the object at the position to which the texture at the corresponding position is mapped. The rendering circuit
155
supplies a two-dimensional transform circuit
156
with a signal of the object to which the texture has been mapped. The two-dimensional transform circuit
156
in turn transforms the three-dimensional object to a two-dimensional image signal produced by mapping the three-dimensional object to a two-dimensional plane based on view point information supplied from the outside. The three-dimensional object transformed into a two-dimensional image signal is further outputted to the outside. The texture may be a still image or a motion picture. With a motion picture, the foregoing operation is performed every time an image frame of the motion picture to be mapped is changed.
The VRML also supports compressed image formats such as JPEG (Joint Photographic Experts Group), which is a highly efficient coding scheme for still images, and MPEG (Moving Picture Experts Group), which is a motion picture coding scheme, as formats for textures to be mapped. In this case, a texture (image) is decoded by decode processing based on a predetermined compression scheme, and the decoded image signal is recorded in the memory
152
in the group of memories
151
.
In the rendering circuit
155
, a texture recorded in the memory
152
is mapped irrespective of whichever format of the image, whether a motion picture or a still image, or its contents. Only one texture stored in the memory can be mapped to a certain polygon at any time, so that a plurality of textures cannot be mapped to a single polygon.
When such three-dimensional information and texture information are transmitted through a transmission path, the information must be compressed before transmission in order to efficiently utilize the transmission path. Particularly, when a motion picture is mapped to a three-dimensional object and in other similar cases, it is essential to compress the motion picture before transmission.
For example, the above-mentioned MPEG scheme has been discussed in ISO-IEC/JTC1/SC2/WG11, and proposed as a standard plan, and a hybrid scheme, which is a combination of motion compensation differential pulse code modulation and DCT (Discrete Cosine Transform) encoding, has been employed. The MPEG defines several profiles and levels for supporting a variety of applications and functions. The most basic one is a main profile main level (MP@ML).
An exemplary configuration of an encoder for MP@ML of the MPEG scheme is described with reference to FIG.
15
. An input image signal is first inputted to a group of frame memories
1
, and stored in a predetermined order. Image data to be encoded is inputted to a motion vector detector circuit
2
in units of macroblocks. The motion vector detector circuit
2
processes image data of each frame as an I-picture, a P-picture, or a B-picture in accordance with a previously set predetermined sequence. It has previously be
Suzuki Teruhiko
Yagasaki Yoichi
Jung Min
Sonnenschein Nath & Rosenthal
Sony Corporation
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