Pulse or digital communications – Bandwidth reduction or expansion – Television or motion video signal
Reexamination Certificate
1999-12-10
2003-06-17
Rao, Andy (Department: 2613)
Pulse or digital communications
Bandwidth reduction or expansion
Television or motion video signal
C375S240080, C375S240260
Reexamination Certificate
active
06580756
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a data transmission method, a data transmission system, a data receiving method, and a data receiving apparatus and, more particularly, to a method for transmitting image data of MPEG4, through the Internet, according to a transmission mode adapted to the type of the image data.
BACKGROUND OF THE INVENTION
In recent years, we have greeted the age of multimedia in which audio, video, and other data are integrally handled, and the conventional information media, i.e., means for transmitting information to men, such as newspapers, magazines, televisions, radios, and telephones, have been adopted as the targets of multimedia. Generally, “multimedia” means media in which, not only characters, but also diagrams, speeches, and especially images are simultaneously expressed in relation with each other. In order to handle the conventional information media as the targets of multimedia, it is necessary to represent the data in digital formats.
When the quantity of data possessed by each of the above-described information media is estimated as the quantity of digital data, in the case of characters, the data quantity per character is only 1~2 byte. However, in the case of speech, the data quantity is 64 kbits per second (quality for telecommunication). Further, in the case of moving picture, the required data quantity is more than 100 Mbits per second (quality for current television broadcasting). So, in the above-described information media, it is not practical to handle such massive data as it is in the digital format. For example, although visual telephones have already been put to practical use by the ISDN (Integrated Services Digital Network) having a transmission ratio of 64 kbps~1.5 Mbps, it is impossible to transmit an image from a television camera as it is by the ISDN.
So, data compression techniques are demanded. For example, for visual telephones, the moving picture compression techniques based on the H.261 and H.263 standards which have been standardized by ITU-T (International Telecommunication Union—Telecommunication Sector) are employed. Further, according to the data compression technique based on the MPEG1 standard, it is possible to record image data as well as audio data in an ordinary music CD (compact disk).
MPEG (Moving Picture Experts Group) is an international standard relating to a data compression technique for an image signal corresponding to a moving picture, and MPEG1 is the standard for compressing moving picture data to 1.5 Mbps, i.e., data of a television signal to about
{fraction (1/100)}. Since the transmission rate of the targets to which the MPEG
1 standard is directed is limited to about 1.5 Mbps, in MPEG2 which has been standardized to meet the demand for higher image quality, moving picture data is compressed to 2~15 Mbps.
Furthermore, under the existing circumstances, standardization of MPEG4 is now proceeded by the working group for standardization of MPEG1 and MPEG2 (ISO/IEC JTC1/SC29/WG11), and this MPEG4 enables coding and signal processing in object units, and hereby realizes new functions required in the age of multimedia.
FIGS. 7
, and
8
(
a
)-
8
(
d
) are diagrams for explaining the object-by-object coding process.
In MPEG4, an image G corresponding to one frame shown in
FIG. 7
is treated as a composite image which is obtained by compositing plural objects. The image G is composed of a background B (FIG.
8
(
a
)), a big fish F
1
as a first foreground (FIG.
8
(
b
)), a small fish F
2
as a second foreground (FIG.
8
(
c
)), and a seaweed F
3
as a third foreground (FIG.
8
(
d
)).
Further, in the object-by-object coding process based on MPEG4, image data corresponding to the respective objects constituting the composite image G (the background B and the first to third foregrounds F
1
~F
3
) are encoded object by object. Then, coded image data (object data) corresponding to the respective objects are transmitted through a transmission medium.
On the other hand, in the object-by-object decoding process based on MPEG4, the coded image data corresponding to the respective objects are received object by object or in the multiplexed state, through the transmission medium. The received coded image data are decoded object by object, thereby generating decoded image data corresponding to each object. Then, the decoded image data corresponding to the respective objects are composited, thereby generating reproduced image data (scene data) corresponding to the composite image (decoded and reproduced image) G.
In the above-described process for transmitting the object-by-object coded image data, not only the coded image data (object data) obtained by coding the image data object by object but also control information are transmitted through the transmission medium. The control information includes, for example, scene description information which indicates the locations of the respective objects in one frame for compositing and displaying the objects, i.e., the display area of the composite image (refer to FIG.
15
(
b
)).
Meanwhile, in recent years, a video distribution system has spread, in which the user can gain access to his/her favorite moving picture through a computer network.
FIG. 9
is a schematic diagram for explaining such video distribution system.
In a video distribution system
700
, a plurality of networks
701
,
702
and
703
are connected to each other, and a plurality of servers
705
,
706
and
707
which distribute video information are connected to the networks
701
,
702
and
703
, respectively. Further, a plurality of video reception and reproduction terminal units (hereinafter referred to simply as “terminal units”) which receive the distributed video information are connected to the respective networks
701
~
703
. To simplify the description, only a terminal unit
704
connected to the network
701
is shown in FIG.
9
.
In the video distribution system
700
so constructed, when the terminal unit
704
receives video information distributed from the server
705
, initially, the terminal unit
704
contacts the server
705
, and effectuates a circuit connection with the server
705
. Thereafter, the terminal unit
704
receives coded image data distributed from the server
705
, and reproduces the image data by decoding.
Hereinafter, a description will be given of a specific process of obtaining predetermined image data through the Internet as the above-described network.
As described above, a plurality of information sources (servers) are connected to the Internet which forms the network in the current information distribution system, and the respective information sources contain, for example, information of home pages relating to various subjects. Now it is assumed that the terminal unit
704
is connected to an information source having information of a home page HP the title of which is “World of Dinosaurs”, and this home page HP is displayed on a display of the terminal unit
704
.
In this home page HP, as shown in
FIG. 10
, items of video scenes relating to dinosaurs are represented by character strings “scene 1”~“scene 3”, and the display areas of these character strings are designation areas D
1
~D
3
for designating the moving pictures. In this state, the user moves the mouse pointer MP to the designation area D
1
corresponding to the character string “scene 1” in the home page HP and clicks the mouse, an image MPs of a video scene P linked to the character string “scene 1” is displayed as shown in FIG.
11
(
a
).
As a data transmission method for transmitting the image (text, audio, and video) data on the Internet, download type transmission and stream type transmission are currently employed.
In the download type transmission, a video file (image data) transmitted from a distribution server is once copied at the terminal and, thereafter, the image corresponding to the video file is reproduced. So, the terminal cannot start image reproduction until the file transmission is completed. That is, there is a latency time for transmission and, therefor
Hagai Makoto
Matsui Yoshinori
Matsushita Electric - Industrial Co., Ltd.
Rao Andy
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