U.S. patent application number 08/881416 was filed with the patent office on 2001-08-09 for video network server for distributing sound and video image information to a plurality of terminals.
This patent application is currently assigned to MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD.. Invention is credited to AKIYOSHI, TAKASHI, ASAI, RIEKO.
Application Number | 20010013129 08/881416 |
Document ID | / |
Family ID | 15797935 |
Filed Date | 2001-08-09 |
United States Patent
Application |
20010013129 |
Kind Code |
A1 |
ASAI, RIEKO ; et
al. |
August 9, 2001 |
VIDEO NETWORK SERVER FOR DISTRIBUTING SOUND AND VIDEO IMAGE
INFORMATION TO A PLURALITY OF TERMINALS
Abstract
A video network server which distributes sound/video image
information to a plurality of terminals comprises a network system
status obtaining section for obtaining status of a video network
system including a video network server, a network and terminals; a
network system status decision section for deciding the status of
the video network system which is obtained by the network system
status obtaining means; a data obtaining method selecting means for
selecting a data obtaining method on the basis of a result which is
decided by the network system status decision means; and a data
obtaining method switching means for performing switching of a data
obtaining method when the method of obtaining data which is
selected by the data obtaining method selecting means is different
from a method of obtaining data at present.
Inventors: |
ASAI, RIEKO; (HIRAKATASHI,
JP) ; AKIYOSHI, TAKASHI; (SAKAISI, JP) |
Correspondence
Address: |
PARKHURST, WENDEL & BURR
1421 PRINCE STREET, SUITE 210
ALEXANDRIA
VA
22314
|
Assignee: |
MATSUSHITA ELECTRIC INDUSTRIAL CO.,
LTD.
|
Family ID: |
15797935 |
Appl. No.: |
08/881416 |
Filed: |
June 24, 1997 |
Current U.S.
Class: |
725/91 ;
348/E7.073 |
Current CPC
Class: |
H04L 65/1101 20220501;
H04L 67/01 20220501; H04N 7/17336 20130101; H04L 65/612 20220501;
H04N 21/2396 20130101; H04L 9/40 20220501 |
Class at
Publication: |
725/91 |
International
Class: |
G06F 015/16; H04N
007/173 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 25, 1996 |
JP |
8-164686 |
Claims
What is claimed is:
1. A video network server which distributes sound/video image
information to a plurality of terminals comprising: a network
system status obtaining section for obtaining status of a video
network system including a video network server, a network and
terminals; a network system status decision section for deciding
the status of the video network system which is obtained by the
network system status obtaining section; a data obtaining method
selecting means for selecting a data obtaining method on the basis
of a result which is decided by the network system status decision
section; and a data obtaining method switching means for performing
switching of a data obtaining method when the data obtaining method
which is selected by the data obtaining method selecting means is
different from a data obtaining method at present.
2. The video network server of claim 1 wherein the network system
status obtaining section includes a network status obtaining means
for obtaining status of the network and the network system status
decision section includes a network status decision means for
deciding the status of the network which is obtained by the network
status obtaining means.
3. The video network server of claim 1 wherein the network system
status obtaining section includes a network server information
obtaining means for obtaining information of the video network
server and the network system status decision section includes a
network server status decision means for deciding status of the
video network server on the basis of the information of the video
network server which is obtained by the network server information
obtaining means.
4. A video network server which distributes sound/video image
information to a plurality of terminals comprising: a network
system status obtaining section for obtaining status of a video
network system including a video network server, a network and
terminals; a network system status decision section for deciding
the status of the network system which is obtained by the network
system status obtaining section; a parameter computing means for
computing parameters including a number of terminals which the
system may allow on the basis of a result which is decided by the
network system status decision section; and a parameter setting
means for setting parameters of the system on the basis of a result
which is computed by the parameter computing means.
5. The video network server of claim 4 wherein the network system
status obtaining section includes a network status obtaining means
for obtaining status of the network and the network system status
decision section includes a network status decision means for
deciding the status of the network which is obtained by the network
status obtaining means.
6. The video network server of claim 4 wherein the network system
status obtaining section includes a network server information
obtaining means for obtaining information of the video network
server and the network system status decision section includes a
network server status decision means for deciding status of the
video network server on the basis of the information of the video
network server which is obtained by the network server information
obtaining means.
7. The video network server of claim 4 further comprises an
allowable quality specifying means for specifying an allowable
range of a quality of reproduced data, the parameter computing
means computing parameters of the system including a number of
terminals which the system may allow on the basis of the allowable
range which is specified by the allowable quality specifying
means.
8. The video network server of claim 7 wherein the network system
status obtaining section includes a network status obtaining means
for obtaining status of the network and the network system status
decision section includes a network status decision means for
deciding the status of the network which is obtained by the network
status obtaining means.
9. The video network server of claim 7 wherein the network system
status obtaining section includes a network server information
obtaining means for obtaining information of the video network
server and the network system status decision section includes a
network server status decision means for deciding status of the
video network server on the basis of the information of the video
network server which is obtained by the video network server
information obtaining means
10. A video network server which distributes sound/video image
information to a plurality of terminals comprising: a data storage
means for storing data; a buffer memory for temporarily storing
data when the data which is requested by a terminal is transferred;
a parameter computing means for allocating a given time interval in
a period which is allocated for a terminal for another terminal
when it is possible to read data which is requested by the terminal
in a time which is less than a given time interval in a
predetermined period; a data prereading means for reading the data
which is requested by the terminal for a given time interval in a
period which is allocated by the parameter computing means from the
data storage means and outputting the data to the buffer memory;
and a data feeding means for feeding the data which is output to
the buffer memory to the terminal.
11. The video network server of claim 10 wherein, when it is
possible to read data which is requested by a terminal in a time
that is not longer than half of a given time interval in a
predetermined period, the parameter computing means allocates a
given time for the terminal every two periods and a given time
interval in a remaining period for another terminal.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a video network server, and
more particularly, to a video network server which selects a data
transfer method or sets various parameters in accordance with
status of a network system in a video network system for
distributing sound/video image information to terminals.
BACKGROUND OF THE INVENTION
[0002] In recent years, with a progress of an image compression
technology or a high-speed digital network technology, a wide
variety of multimedia systems are increasingly constructed. In
order to construct a multimedia network system by combining various
equipments using a general computer and operate it smoothly, there
is a need for a function for setting various parameters such as a
time slot period and a time slot size or a number of allowable
terminals according to status of the system and a function for
reconstructing the system by resetting these various parameters in
accordance with change of status.
[0003] A description is given of time slot management of the video
server which decides setting of parameters with reference to FIG.
35. Since it is difficult to distribute data to each terminal in a
given ratio in a network system including a plurality of terminals
only by reading and transferring the data sequentially,
particularly in the case of using motion picture data of a large
capacity, a time slot management method wherein data is sent to
each terminal periodically for a given time is generally employed
in the video network server. As shown in FIG. 35, the video server
divides a given time interval, i e, a time slot period uniformly
and allocates the divided given time interval to each terminal. The
time allocated to each terminal in a time slot period is a time
slot size. The video server reads and transfers data to each
terminal for each time slot size, thereby distributing data to a
plurality of terminals in a given ratio. As shown in FIG. 35, data
is sequentially read and transferred for each time slot size as
follows: data A1 to a terminal A.fwdarw.data B1 to a terminal
B.fwdarw.data C1 to a terminal C (one time slot period).fwdarw.data
A2 to the terminal A . . . . Conventionally, a time slot period and
a time slot size are decided when parameters are set in the video
server and then; on the basis of the time slot period and the time
slot size, a number of allowable terminals or a response speed,
i.e., the other parameters are decided.
[0004] A description is given of a function for setting various
parameters for operating a system in a video net work server which
distributes sound/video image information or the like to a
plurality of terminals employed conventionally with reference to
figures.
[0005] FIG. 34 is a diagram illustrating a prior art video network
server. In the figure, a parameter computing means 901 is for
computing parameters in accordance with a construction of a system.
The construction of the system includes a number or performance of
storage devices such as connected disks, or a capacity of a memory
mounted in the system, for example. A parameter computation
information holding means 902 is for holding information with which
the parameter computing means 901 computes parameters. A parameter
setting means 903 is for setting the parameters computed by the
parameter computing means 901 in the system. Actually, various
components such as a system construction checking means for
checking the construction of the system are necessary, and are
dispensed with herein.
[0006] The prior art server constructed above operates as follows
in setting parameters. The parameter computation information
holding means 902 holds information as to the construction of the
system such as a type and a number of disks as storage devices or a
capacity of a memory, or information for setting parameters such as
a formula for computing parameters on the basis of the former
information. The parameter computing means 901 computes parameters
such as the time slot period and the time slot size in the time
slot management mentioned above or the number of allowable
terminals or the transfer speed in view of performance in
accordance with the construction of the system, on the basis of the
information which is held by the parameter computation information
holding means 902. The parameter setting means 903 sets the
parameters which are computed by the parameter computing means 903
in the system
[0007] The video network system is operated according to thus set
parameters, and when the construction and status of the system
change, parameters are reset following the procedure
[0008] In the prior art server, when parameters are computed or
set, it is possible to compute and set appropriate parameters in
view of factors determined by the constructions of the system such
as the number or performance of disks, but it is difficult to
compute and set appropriate parameters in view of external and
dynamic factors such as change of network operating form or change
of network traffic (congestion). Therefore, if performance of the
system with parameters initially set is degraded due to changes of
the external factors, the system is operated without changing
initialization, so that status of the network becomes worse than
predicted and the server is overloaded, causing damaging effects on
use of data. On the other hand, when status of the network is more
preferable than predicted, performance of the system is degraded
without making the best use of a reserve power of the system.
[0009] In the former case in which status of the system becomes
worse than predicted, when traffic of the network increases or the
network server is overloaded in reproducing motion picture data at
the terminal, discontinuity of sound of data occurs or response of
the server becomes worse, causing stop of reproduction.
[0010] In this case, since response of the server is worse than
predicted, changing parameters of the system which decides response
speed such as making the time slot period shorter than normal,
limiting the number of allowable terminals must be performed, or
when operating status is worse than described above, which is
difficult to cope with by changing parameters, it is difficult to
avoid the adverse effects without taking actions for reducing load
of the server, such as performing switching of a method of
obtaining data so as to transfer all data to terminals and
reproduce the data at the terminals. As the method of obtaining
data, a method wherein terminals receive data which is reproduced
by the server itself using NFS protocol, for example, is less
burdensome and desirable to the terminals. However, when status of
the server or the network is worse and the adverse effects occur,
it is desirable to transfer all data to the terminals and reproduce
the data at the terminals using FTP protocol, since discontinuity
of data is avoided.
[0011] In the latter case, the reserve power of the server is not
made the best use of if status of the network is more preferable
than predicted. For example, when the system is set to transfer all
motion picture data to the terminals and reproduce the data at the
terminals or the number of allowable terminals is limited severely
allowing for congestion of the network or load of the server, it is
impossible to reproduce data or to increase terminals to which data
is supplied, with the server less overloaded than predicted. In
another case, assuming that data requiring a fast transfer rate is
used, when a time slot period is set according to its required
transfer rate, use of data of required transfer rate which is lower
than predicted causes time of no use in a time slot.
[0012] In the prior art server, in order to improve the
above-described problem which may occur when status of the system
changes, the user must interrupt operation of the system
consciously and check its status, and then change parameters or
various conditions.
[0013] In some cases, the user demands that discontinuity of sound
or stop of reproduction be avoided with a number of terminals
limited, while the user demands that many terminals be used with
discontinuity of sound or stop of reproduction occurring in some
degree. However, parameters cannot be changed with flexibility
depending on allowable qualities in the prior art server
system.
SUMMARY OF THE INVENTION
[0014] It is an object of the present invention to provide a video
network work server wherein switching of a method of obtaining data
can be performed in accordance with busy status of the network or
status of the server in operating the system, thereby data is
transferred with reliability and a reproduction quality is
improved.
[0015] It is another object of the present invention to provide a
video network server wherein parameters are changed and a limited
number of terminals which the system may allow is changed in
accordance with busy status of the network or status of the server
in operating the system, thereby data is transferred with
reliability and a reproduction quality is improved.
[0016] It is still another object of the present invention to
provide a video network server wherein a number of allowable
terminals can be set in accordance with allowable qualities of data
specified by the user in addition to change of parameters according
to status of the system, thereby it is possible to set the system
with flexibility in operating the system.
[0017] It is a further object of the present invention to provide a
video network server wherein parameters of the system can be
changed and time slot management can be adjusted depending on a
transfer rate of data which is requested by each terminal in
operating the system, thereby performance of the system is
improved.
[0018] Other objects and advantages of the invention will become
apparent from the detailed description that follows. The detailed
description and specific embodiments described are provided only
for illustration since various additions and modifications within
the scope of the invention will be apparent to those of skill in
the prior art from the detailed description.
[0019] According to a first aspect of the present invention, a
video network server which distributes sound/video image
information to a plurality of terminals comprises a network system
status obtaining section for obtaining status of a network system
including a network server, a network and terminals; a network
system status decision section for deciding the status of the
network system which is obtained by the network system status
obtaining section; a data obtaining method selecting means for
selecting a data obtaining method on the basis of a result which is
decided by the network system status decision section; and a data
obtaining method switching means for performing switching of a data
obtaining method when the data obtaining method which is selected
by the data obtaining method selecting means is different from a
data obtaining method at present.
[0020] According to a second aspect of the present invention, the
video network server according to the first aspect includes a
network status obtaining means for obtaining status of the network
as the network system status obtaining section and a network status
decision means for deciding the status of the network which is
obtained by the network status obtaining means as the network
system status decision section.
[0021] According to a third aspect of the present invention, the
video network server according to the first aspect includes a
network server information obtaining means for obtaining
information of the network server as the network system status
obtaining section and a network server status decision means for
deciding status of the network server on the basis of the
information of the network server which is obtained by the network
server information obtaining means as the network system status
decision section.
[0022] According to a fourth aspect of the present invention, a
video network server which distributes sound/video image
information to a plurality of terminals comprise a network system
status obtaining section for obtaining status of a network system
including a network server, a network and terminals; a network
system status decision section for deciding the status of the
network system which is obtained by the network system status
obtaining section; a parameter computing means for computing
parameters including a number of terminals which the system may
allow on the basis of a result which is decided by the network
system status decision section; and a parameter setting means for
setting parameters of the system on the basis of a result which is
computed by the parameter computing means.
[0023] According to a fifth aspect of the present invention, the
video network server according to the fourth aspect includes a
network status obtaining means for obtaining status of the network
as the network system status obtaining section and a network status
decision means for deciding the status of the network which is
obtained by the network status obtaining means as the network
system status decision section.
[0024] According to a sixth aspect of the present invention, the
video network server according to the fourth aspect includes a
network server information obtaining means for obtaining
information of the network server as the network system status
obtaining section and a network server status decision means for
deciding status of the network server on the basis of the
information of the network server which is obtained by the network
server information obtaining means as the network system status
decision section.
[0025] According to a seventh aspect of the present invention, the
video network server according to the fourth aspect further
comprises an allowable quality specifying means for specifying an
allowable range of a quality of reproduced data, the parameter
computing means computing parameters of the system including a
number of terminals which the system may allow on the basis of the
allowable range specified by the allowable quality specifying
means.
[0026] According to an eighth aspect of the present invention, the
video network server according to the seventh aspect includes a
network status obtaining means for obtaining status of the network
as the network system status obtaining section and a network status
decision means for deciding the status of the network which is
obtained by the network status obtaining means as the network
system status decision section.
[0027] According to a ninth aspect of the present invention, the
video network server according to the seventh aspect includes a
network server information obtaining means for obtaining
information of the network server as the network system status
obtaining section and a network server status decision means for
deciding status of the network server on the basis of the
information of the network server which is obtained by the network
server information obtaining means as the network system status
decision section.
[0028] According to a tenth aspect of the present invention, a
video network server which distributes sound/video image
information to a plurality of terminals comprises a data storage
means for storing data; a buffer memory for temporarily storing
data to be transferred; a parameter computing means for allocating
a given time interval in a period which is allocated for a terminal
for another terminal when it is possible to read data which is
requested by the terminal in a time that is less than a given time
interval in a predetermined period; a data prereading means for
reading the data which is requested by the terminal for a given
time interval in a period which is allocated by the parameter
computing means from the data storage means and outputting the data
to the buffer memory; and a data feeding means for feeding the data
which is output to the buffer memory to the terminal.
[0029] According to an eleventh aspect of the present invention,
the video network server according to the tenth aspect wherein,
when it is possible to read data which is requested by a terminal
in half of a given time interval in a predetermined period, the
parameter computing means allocates a given time for the terminal
every two periods and a given time interval in a remaining period
for another terminal.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] FIG. 1 is a block diagram illustrating a video server
according to a first embodiment of the present invention.
[0031] FIG. 2 is a flow chart illustrating a reproducing operation
of the video network server.
[0032] FIG. 3 is a flow chart illustrating a recording operation of
the video network server.
[0033] FIG. 4 is a block diagram illustrating a video network
server according to a second embodiment of the present
invention.
[0034] FIG. 5 is a flow chart illustrating a reproducing operation
of the video network server.
[0035] FIG. 6 is a flow chart illustrating a recording operation of
the video network server.
[0036] FIG. 7 is a block diagram illustrating a video network
server according to a third embodiment of the present
invention.
[0037] FIG. 8 is a flow chart illustrating a reproducing operation
of the video server.
[0038] FIG. 9 is a flow chart illustrating a recoding operation of
the video network server.
[0039] FIG. 10 is a block diagram illustrating a video network
server according to a fourth embodiment of the present
invention.
[0040] FIG. 11 is a flow chart illustrating a reproducing operation
of the video network server.
[0041] FIG. 12 is a flow chart illustrating a recording operation
of the video network server.
[0042] FIG. 13 is a block diagram illustrating a video network
server according to a fifth embodiment of the present
invention.
[0043] FIG. 14 is a flow chart illustrating a reproducing operation
of the video server.
[0044] FIG. 15 is a flow chart illustrating a recording operation
of the video network server.
[0045] FIG. 16 is a block diagram illustrating a video network
server according to a sixth embodiment of the present
invention.
[0046] FIG. 17 is a flow chart illustrating a reproducing operation
of the video server.
[0047] FIG. 18 is a flow chart illustrating a recording operation
of the video network server.
[0048] FIG. 19 is a flow chart illustrating an operation of a video
network server according to a seventh embodiment of the present
invention.
[0049] FIG. 20 is a flow chart illustrating a reproducing operation
of the video network server.
[0050] FIG. 21 is a flow chart illustrating a recording operation
of the video network server.
[0051] FIG. 22 is a block diagram illustrating a video network
server according to an eighth embodiment of the present
invention.
[0052] FIG. 23 is a flow chart illustrating a reproducing operation
of the video network server.
[0053] FIG. 24 is a flow chart illustrating a recording operation
of the video network server.
[0054] FIG. 25 is a block diagram illustrating a video network
server according to a ninth embodiment of the present
invention.
[0055] FIG. 26 is a flow chart illustrating a reproducing operation
of the video network server.
[0056] FIG. 27 is a flow chart illustrating a recording operation
of the video network server.
[0057] FIG. 28 is a block diagram illustrating a video network
server according to a tenth embodiment.
[0058] FIG. 29 is a flow chart illustrating an operation of the
video network server according to a tenth embodiment of the present
invention.
[0059] FIG. 30 is a diagram illustrating parameters of a system
preset in the video network server according to the tenth
embodiment of the present invention.
[0060] FIG. 31 is a diagram illustrating distribution of time in
operating the video network server according to the tenth
embodiment of the present invention.
[0061] FIG. 32 is a diagram illustrating distribution of time in
operating the video network server according to the tenth
embodiment of the present invention.
[0062] FIG. 33 is a diagram illustrating distribution of time in
operating the video network server according to the tenth
embodiment of the present invention.
[0063] FIG. 34 is a block diagram illustrating a prior art video
network server.
[0064] FIG. 35 is a diagram for explaining time slot management of
the video network server.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0065] [Embodiment 1]
[0066] A video network server according to a first embodiment of
the present invention has a capability of performing switching of a
data transfer method depending on status of a network.
[0067] FIG. 1 is a block diagram illustrating a video network
server according to a first embodiment of the present invention. In
the figure, reference numeral 101 designates a network interface
through which the video network server is connected to a network. A
network status obtaining means 102 is for obtaining status of the
network. A network status decision means 103 is for deciding the
status of the network which is obtained by the network status
obtaining means 102. A data obtaining method selecting means 104 is
for selecting a data obtaining method. A data obtaining method
switching means 105 is for performing switching of a data obtaining
method when the data obtaining method which is selected by the data
obtaining method selecting means 104 is different from a data
obtaining method at present. FIG. 2 is a flow chart illustrating a
reproducing operation of the server according to the first
embodiment.
[0068] A description is given of an operation of the video network
server according to first embodiment with reference to FIGS. 1 and
2.
[0069] In step 207, the network status obtaining means 102 obtains
busy status of the network. One example of the busy status of the
network is "network traffic information (degree of congestion of
the network which is represented by a number of packets or packets
lost due to collision through a network)". The network status
obtaining means 102 obtains a total number of packets as traffic
information. Subsequently in step 208, the network status decision
means 103 decides busy status of the network. At this time, as a
decision criterion of the busy status of the network, "whether a
number of network traffic is larger than a number X or not" is
employed. The number X is precomputed, indicating that data can be
reproduced in the server when the number of network traffic is not
larger than X. In this case, it is decided whether the total number
of packets is larger than X or not.
[0070] When it is decided that the number of network traffic is
larger than the number X" in step 208, the data obtaining method
selecting means 104 selects a method wherein all data is copied
into the terminal from the network server and the data is
reproduced at the terminal using network protocol such as FTP in
step 205. The data obtaining method switching means 105 switches a
data obtaining method to the method which is selected by the data
obtaining method selecting means 104 when the selected data
obtaining method is not employed at present, so that data is copied
into the terminal using FTP protocol. In step 206, the terminal
itself reproduces copied date.
[0071] When it is decided that the number of the network traffic is
not larger than X, it is assumed that data can be reproduced in the
server, so that the data obtaining method selecting means 104
selects a method wherein data which is reproduced in the server is
transferred to the terminal using NFS protocol and the data
obtaining method switching means 105 switches a data obtaining
method to the selected data obtaining method when the selected data
obtaining method is not employed at present, and then in step 211
data is reproduced in the video network server.
[0072] Thus, in accordance with the video network server of the
first embodiment of the present invention, network traffic
information is obtained to decide status of the network by the
network status obtaining means and the network status decision
means; and switching of the data obtaining method is performed
between two methods, i.e., the method of reproducing data in the
server, and the method of copying data into the terminal and
reproducing the data at the terminal according to status of the
network, by the data obtaining method selecting means and by the
data obtaining method switching means. Therefore, an appropriate
data obtaining method can be selected according to status of the
system with no need for the user to consciously interrupt and
change operation of the system. As a result, data can be reproduced
with reliability and qualities of reproduced data are improved.
[0073] Reproduction of a motion picture at the terminal has been
described as switching of the data obtaining method at the terminal
in description of the operation of the video network server.
Alternatively, when data is transferred from terminals and the data
is recorded in the storage device of the server, a transfer method
is selected according to status following a procedure of a flow
chart illustrated in FIG. 3, so that reliability of recording and
qualities of recorded data can be improved.
[0074] In addition, in the video network server of the first
embodiment, the network status obtaining means, the network status
decision means, the data obtaining method selecting means, and the
data obtaining method switching means are held on the server.
Alternatively, these means may be held independently in each
terminal, or may be held on another network equipment as a separate
apparatus. In this case, the network status obtaining means in the
terminal obtains status of the network, the network status decision
means makes a decision on the obtained result, the data obtaining
method selecting means in the terminal selects a data obtaining
method, and the data obtaining method switching means switches a
data obtaining method to the selected data obtaining method (in
this case FTP protocol or NFS protocol).
[0075] Although the method using the FTP protocol and the NFS
protocol is illustrated as an example of the data obtaining method,
the method is not limited to this and switching can be performed
among various data obtaining methods.
[0076] Further, as an example of information which is obtained by
the network status obtaining means, having illustrated the number
of packets or the number of packets lost due to collision through
the network, it is not limited to information illustrated in this
case, provided that the information indicates status of the network
traffic.
[0077] [Embodiment 2]
[0078] A video network server according to a second embodiment of
the present invention can perform switching of a data transfer
method depending on status of the network server.
[0079] FIG. 4 is a block diagram illustrating the video network
server of the second embodiment. In the figure, a network server
information obtaining means 110 is for obtaining information of the
network server. A network server status decision means 111 is for
deciding status of the network server on the basis of the
information which is obtained by the network server information
obtaining means 110. The other reference characters are identical
to those in the first embodiment and will not be discussed. FIG. 5
is a flow chart illustrating an operation of the server of the
second embodiment.
[0080] A description is given of an operation of the video network
server of the second embodiment with reference to FIGS. 4 and
5.
[0081] In step 203, the network server information obtaining means
110 obtains information of the network server. The information of
the network server includes, for example, "response time of the
network server", which is obtained as information of the server.
Subsequently in step 204, the network server status decision means
111 makes a decision on the information of the network server which
is obtained in step 203 using "response time of the network server
is longer than time T" as a decision criterion. The time T
indicates a precomputed number, indicating that data can be
reproduced in the server when the response time is not longer than
T. In this case, it is decided whether the response time is longer
than T or not.
[0082] When it is decided that the response time of the network
server is longer than the time T, in step 205, the data obtaining
method selecting means 104 selects a method wherein all data is
copied into the terminal using network protocol such as FTP from
the network server and the data obtaining method switching means
105 performs switching of a data obtaining method when the selected
data obtaining method is not employed, and then in step 206, copied
data is reproduced at the terminal.
[0083] When it is decided that the response time of the network
server is not longer than the time T in step 204, the data
obtaining method selecting means 104 selects a method wherein data
which is reproduced in the server is transferred to the terminal
using NFS protocol and the data obtaining method switching means
105 performs switching of a data obtaining method when the selected
data obtaining method is not employed, and then in step 211, data
which is reproduced in the server is transferred from the video
network server to the terminal using NFS protocol.
[0084] Thus, in accordance with the video network server of the
second embodiment of the present invention, status of the network
server is decided by the network server information obtaining means
and the network server status decision means, and switching of the
data obtaining method is performed between two methods, i.e., the
method of reproducing data in the server, and the method of copying
data into the terminal and reproducing the data at the terminal,
according to status of the network server by the data obtaining
method selecting means and by the data obtaining method switching
means. Therefore, an appropriate data obtaining method can be
selected according to status of the system with no need for the
user to consciously interrupt and change operation of the system.
As a result, data can be reproduced with reliability and qualities
of reproduced data are improved.
[0085] In the video network server according to the second
embodiment as in the first embodiment, when data is transferred
from the terminal and the data is recorded in the storage device of
the server, a transfer method can be selected depending on the
situation following a procedure of a flow chart illustrate in FIG.
6. As a result, reliability of recording and qualities of recoded
data can be improved.
[0086] The network server information obtaining means, the network
server status decision means, the data obtaining method selecting
means, and the data obtaining method switching means may be held
independently in each terminal or may be held on another network
equipment as a separate apparatus.
[0087] Further, the data obtaining method is not limited to FTP
protocol and NFS protocol. Information of the network server which
is obtained by the network server information obtaining means 110
is not limited to "response time of the network server" and
information such as "a number of lost packets/a number of acquired
packets" will do, as long as they indicate operating state
[0088] [Embodiment 3]
[0089] A video network server according to a third embodiment of
the present invention can perform switching of a data transfer
method depending on status of the network server and status of the
network.
[0090] FIG. 7 is a block diagram illustrating a video network
server according to a third embodiment of the present invention. In
the figure, a network server information obtaining means 110 is for
obtaining information of the network server. A network server
status decision means 111 is for deciding status of the network
server on the basis of the information which is obtained by the
network server information obtaining means 110. The other reference
characters are identical to those in the first embodiment and will
not be discussed. FIG. 8 is a flow chart illustrating an operation
of the server according to the third embodiment.
[0091] A description is given of an operation of the video network
server of the third embodiment with reference to FIGS. 7 and 8.
[0092] In step 203, the network server information obtaining means
110 obtains response time of the network server as information of
the network server. Subsequently in step 204, the network server
status decision means 111 makes a decision on the information of
the network server which is obtained in step 203 using "whether
response time of the network server is longer than time T or not"
as a decision criterion. The time T is identical to that in the
second embodiment.
[0093] When it is decided that the response time of the network
server is longer than the time T, in step 205, the data obtaining
method selecting means 104 selects a method wherein all data is
copied into the terminal from the network server using network
protocol such as FTP and the data obtaining method switching means
105 performs switching of a data obtaining method when the selected
data obtaining method is not employed, and then in step 206, copied
data is reproduced at the terminal.
[0094] When it is decided that the response time of the network
server is not longer than the time T in step 204, the network
status obtaining means 102 obtains a total number of packets as
busy status of the network in step 207. Subsequently in step 208,
the network status decision means 103 makes a decision on busy
status of the network using "whether a number of network traffic is
larger than the number X or not". The number X is identical to that
in the first embodiment.
[0095] When it is decided that the number of network traffic is
larger than the number X in step 208, the data obtaining method
selecting means 104 selects a method wherein all data is copied
into the terminal from the network server and the data is
reproduced at the terminal using network protocol such as FTP in
step 205. The data obtaining method switching means 105 switches a
data obtaining method to the method which is selected by the data
obtaining method selecting means 104 when the selected data
obtaining method is not employed, so that data is copied into the
terminal using FTP protocol. In step 206, the terminal itself
reproduces copied data.
[0096] When it is decided that the number of network traffic is not
larger than X in step 208; the data obtaining method selecting
means 104 selects a method wherein data which is reproduced in the
server is transferred to the terminal using NFS protocol and the
data obtaining method switching means 105 performs switching of a
data obtaining method to the data obtaining method which is
selected by the data obtaining method selecting means 104 when the
selected data obtaining method is not employed, and then in step
211 data is reproduced in the video network server.
[0097] Thus, in accordance with the video network server of the
third embodiment, status of the network server is decided by the
network server information obtaining means and the network server
status decision means, status of the network is decided by the
network status obtaining means and the network status decision
means, and switching of the data obtaining method is performed
between two methods, i.e., the method of reproducing data in the
server, and the method of copying data into the terminal and
reproducing the data at the terminal, according to status of the
network server and status of the network by the data obtaining
method selecting means and the data obtaining method switching
means. Therefore, an appropriate data obtaining method can be
selected according to status of the system with no need for the
user to consciously interrupt and change operation of the system.
As a result, data can be reproduced with reliability and qualities
of reproduced data are improved.
[0098] In the video network server according to the third
embodiment as in the first embodiment, when data is transferred
from the terminal and the data is recorded in the storage device of
the server, a transfer method can be selected depending on the
situation following a procedure of a flow chart illustrated in FIG.
9. As a result, reliability of recording and qualities of recoded
data can be improved.
[0099] The network status obtaining means, the network status
decision means, the network server information obtaining means, the
network server status decision means, the data obtaining method
selecting means, and the data obtaining method switching means may
be held independently in each terminal or may be held on another
network equipment as a separate apparatus.
[0100] The data obtaining method is not limited to FTP protocol and
NFS protocol, information which is obtained by the network status
obtaining means is not limited to the total number of packets or
the number of packets lost due to collision, and information which
is obtained by the network server information obtaining means is
not limited to the response rime of the server.
[0101] In the third embodiment, status of the network server is
decided and then status of the network is decided. This may be
performed in an arbitrary order.
[0102] [Embodiment 4]
[0103] A video network server according to a fourth embodiment of
the present invention can change a number of allowable terminals
depending on status of the network.
[0104] FIG. 10 is a block diagram illustrating a video network
server according to a fourth embodiment of the present invention.
In the figure, reference numeral 101 designates a network interface
through which the video network server is connected to a network. A
network status obtaining means 102 is for obtaining status of the
network. A network status decision means 103 is for deciding the
status of the network which is obtained by the network status
obtaining method 102. A parameter computing means 107 is for
computing parameters of the system. A parameter setting means 108
is for setting the parameters which are computed by the parameter
computing means 107 in the system. FIG. 11 is a flow chart
illustrating an operation of the server of the fourth
embodiment.
[0105] A description is given of an operation of the video network
server of the fourth embodiment with reference FIGS. 10 and 11.
[0106] In step 207, the network status obtaining means 102 obtains
a total number of packets as busy status of the network.
Subsequently in step 209, the network status decision means 103
decides busy status of the network. At this time, "whether a number
of network traffic is larger than a number Y or not" is employed as
a decision criterion of busy status of the network. The number Y is
precomputed, indicating that when the number of network traffic is
not larger than Y, data can be reproduced in the server for
allowable terminals then. In this case, it is decided whether a
total number of packets is larger than the number Y or not.
[0107] When it is decided that the number of network traffic is
larger than the number Y in step 209, it is assumed that the server
is overloaded in present status of the network, so that the
parameter computing means 107 limits the number of allowable
terminals to a number that is smaller than the number of terminals
at present, and when data requests are issued from terminals more
than them, the parameter computing means 107 recomputes parameters
of the system so that the network server will not receive the data
requests, and the parameter setting means 108 sets the parameters
which are recomputed by the parameter computing means 107 in the
system. In step 211, the video network server transfers data which
is reproduced in the server to the terminal using NFS protocol.
[0108] When it is decided that the number of network traffic is not
larger than the number Y in step 209, in step 211, the video
network server transfers the data which is reproduced in the server
to the terminal using NFS protocol with parameters of the system
unchanged.
[0109] Thus, in accordance with the video network server of the
fourth embodiment of the present invention, traffic information
indicating degree of congestion of the network is obtained to
decide status of the network by the network status obtaining means
and by the network status decision means, and the number of
allowable terminals can be changed according to status of the
network by the parameter computing means and by the parameter
switching means. Therefore, when status of the network is worse,
the number of allowable terminals is limited more severely so as
not to increase congestion, thereby troubles such as discontinuity
of data are avoided. As a result, motion picture data can be
reproduced with reliability and qualities of reproduced data are
improved.
[0110] Reproduction of motion picture at the terminal has been
described as changing of the number of allowable terminals, for
explaining the operation of the video network server according to
the fourth embodiment. Alternatively, when data is transferred from
the terminal and the data is recorded in the storage device of the
server, a number of allowable terminals can be set depending on
situations, following a procedure of a flow chart illustrated in
FIG. 12 . As a result, reliability of recording and qualities of
recorded data are improved.
[0111] The network status obtaining means, the network status
decision means, the network server information obtaining means, the
network server status decision means, the parameter computing
means, and the parameter setting means may be held independently in
each terminal, or may be held on another network equipment as a
separate apparatus.
[0112] Information which is obtained by the network status
obtaining means is not limited to the total number of packets.
[0113] [Embodiment 5]
[0114] A video network server according to a fifth embodiment of
the present invention can change a number of allowable terminals
depending on status of the network server.
[0115] FIG. 13 is a block diagram illustrating a video network
server according to a fifth embodiment of the present invention. In
the figure, a network server information obtaining means 110 is for
obtaining information of the network server. A network server
status decision means 111 is for deciding status of the network
server on the basis of the information which is obtained by the
network server information obtaining means 110. The other reference
characters are identical to those in the fourth embodiment and will
not be discussed. FIG. 14 is a flow chart illustrating an operation
of the server of the fifth embodiment.
[0116] A description is given of an operation of the video network
server of the fifth embodiment with reference to FIGS. 13 and
14.
[0117] In step 203, the network server information obtaining means
110 obtains a response time of the network server as information of
the network server. Subsequently in step 204, the network server
status decision means 111 makes a decision on the information of
the network server which is obtained in step 203 using "whether
response time of the network server is longer than time T or not"
as a decision criterion. The time T is precomputed, indicating that
when the response time is not longer than the time T, data can be
reproduced in the server for allowable terminals then. At this time
it is decided whether the response time is longer than T or
not.
[0118] When it is decided that the response time of the network
server is longer than the time T, it is assumed that the server is
overloaded, so that the parameter computing means 107 limits the
number of allowable terminals to a number that is smaller than the
number of terminals at present, and when data requests are issued
from terminals more than them, the parameter computing means 107
recomputes parameters of the system so that the network server will
not receive the data requests, and the parameter setting means 108
sets the parameters which are recomputed by the parameter computing
means 107 in the system. In step 211, the video network server
transfers data which is reproduced in the server to the terminal
using NFS protocol.
[0119] When it is decided that the response time of the network
server is not longer than the time T in step 204, in step 211, the
video network server transfers the data which is reproduced in the
server to the terminal using NFS protocol with parameters of the
system unchanged.
[0120] In the video network server of the fifth embodiment,
information such as the response time of the network server is
obtained to decide its status by the network server information
obtaining means and by the network server status decision means,
and a number of allowable terminals can be changed according to
status of the network server by the parameter computing means and
by the parameter switching means. Therefore, when the network
server is overloaded, the number of allowable terminals is limited
more severely, thereby a service to the terminal supported at
present is not adversely affected by degraded response of the
server, and troubles such as discontinuity of data are avoided. As
a result, motion picture data can be reproduced with reliability
and qualities of reproduced data are improved.
[0121] In the video network server according to the fifth
embodiment as in the fourth embodiment, when data is transferred
from the terminal and the data is recorded in a storage device in
the server, a number of allowable terminals can be set according to
the situation following a procedure of a flow chart illustrated in
FIG. 15. As a result, reliability of recording and qualities of
recorded data are improved.
[0122] The network server information obtaining means, the network
server status decision means, the parameter computing means, and
the parameter setting means may be held independently in each
terminal or may be held on another network equipment as a separate
apparatus.
[0123] Information which is obtained by the network server
information obtaining means is not limited to the response time of
the server.
[0124] [Embodiment 6]
[0125] A video network server according to a sixth embodiment of
the present invention can change a number of allowable terminals
depending on status of a network and status of a network
server.
[0126] FIG. 16 is a block diagram illustrating a video network
server according to the sixth embodiment of the present invention.
In the figure, a network server information obtaining means 110 is
for obtaining information of the network server. A network server
status decision means 111 is for deciding status of the network
server on the basis of the information which is obtained by the
network server information obtaining means 110. The other reference
characters are identical to those in the fourth embodiment and will
not be discussed. FIG. 17 is a flow chart illustrating an operation
of the server according to the sixth embodiment.
[0127] A description is given of an operation of the video network
server according to the sixth embodiment with reference to FIGS. 16
and 17.
[0128] In step 203, the network server information obtaining means
110 obtains a response time of the network server as information of
the network server. Subsequently in step 204, the network server
status decision means 111 makes a decision on the information of
the network server which is obtained in step 203 using "whether
response time of the network server is longer than time T or not"
as a decision criterion. The time T is identical to that in the
fifth embodiment.
[0129] When it is decided that the response time of the network
server is longer than the time T, the parameter computing means 107
limits the number of allowable terminals to a number which is
smaller than the number of terminals at present, and when data
requests are issued from terminals more than them, the parameter
computing means 107 recomputes parameters of the system so that the
network server will not receive the data requests, and the
parameter setting means 108 sets the parameters which are
recomputed by the parameter computing means 107 in the system. In
step 211, the video network server transfers data which is
reproduced in the server to the terminal using NFS protocol.
[0130] When it is decided that the response time of the network
server is not longer than the time T in step 204, the network
status obtaining means 102 obtains network traffic (a total number
of packets) as busy status of the network in step 207. Subsequently
in step 209, the network status decision means 103 decides busy
status of the network using "whether a number of the network
traffic is larger than a number Y or not". The number Y is
identical to that in the fourth embodiment.
[0131] When it is decided that a number of the network traffic is
larger than the number Y in step 209, the parameter computing means
107 limits the number of allowable terminals to a number that is
smaller than the number of terminals at present, and when data
requests are issued from terminals more than them, the parameter
computing means 107 recomputes parameters of the system so that the
network server will not receive the data requests, and the
parameter setting means 108 sets the parameters which are
recomputed by the parameter computing means 107 in the system. In
step 211, the video network server transfers data which is
reproduced in the server to the terminal using NFS protocol.
[0132] When it is decided that the number of the network traffic is
not larger than the number Y in step 209, it is assumed that the
system will be operated in present status of the network, in step
211, the video network server transfers the data which is
reproduced in the server to the terminal using NFS protocol with
parameters of the system unchanged.
[0133] Thus, in accordance with the video network server of the
sixth embodiment, status of the network server is decided by the
network server information obtaining means and by the network
server status decision means, and status of the network is decided
by the network status obtaining means and by the network status
decision means, a number of allowable terminals can be changed
according to status of the network server and status of the network
by the parameter computing means and by the parameter setting
means. Therefore, when the network server is overloaded or the
network is in poor status, a number of allowable terminals is
limited more severely, thereby data transfer to the terminals
supported at present is not adversely affected by congestion of the
network or degraded response of the server. As a result, motion
picture data can be reproduced with reliability and qualities of
reproduced data are improved.
[0134] In the video network server according to the sixth
embodiment as in the fourth embodiment, when data is transferred
from the terminal and the data is recorded in a storage device of
the server, a number of allowable terminals can be set depending on
the situation following a procedure of a flow chart illustrated in
FIG. 18. As a result, reliability of recording and qualities of
recorded data are improved.
[0135] The network status obtaining means, the network status
decision means, the network server information obtaining means, the
network server status decision means, the parameter computing
means, and the parameter setting means may be held in each terminal
independently, or may be held on another network equipment as a
separate apparatus.
[0136] Information which is obtained by the network status
obtaining means is not limited to the total number of packets, and
information which is obtained by the network server information
obtaining means is not limited to the response time of the
server.
[0137] In the sixth embodiment, status of the network server is
decided, and then status of the network is decided. Alternatively,
this order may be reversed.
[0138] [Embodiment 7]
[0139] A video network server according to a seventh embodiment of
the present invention can change a number of allowable terminals
depending on an allowable range of a quality of reproduced data
specified by the user and status of the network.
[0140] FIG. 19 is a block diagram illustrating a video network
server according to the seventh embodiment of the present
invention. In the figure, reference numeral 109 designates an
allowable quality specifying means to which the user inputs an
allowable range of a quality of reproduced data. The other
reference characters are identical to those in the fourth
embodiment and will not be discussed. FIG. 20 is a flow chart
illustrating an operation of the server of the seventh
embodiment.
[0141] A description is given of an operation of the video network
server of the seventh embodiment with reference to FIGS. 19 and
20.
[0142] In step 201, it is decided whether information of the
allowable range of the quality of reproduced data is input to the
allowable range specifying means 109 by the user or not. This
allowable range includes, for example, "discontinuity of sound of
data occurs N times or less an hour", "interval of data
discontinuity in minutes" or "interval of data discontinuity in
minutes for several seconds." When this information is input, in
step 202, the parameter computing means 107 computes parameters on
the basis of the input information and the parameter setting means
108 sets the computed parameters in the system. Generally, using a
larger allowable range, for example, the more frequently
discontinuity of sound of data occurs, the more terminals the
system can support or the higher a transfer rate of reproducible
data is. Using a smaller allowable range, it is reversed. In step
201, when the allowable quality is not specified by the user, the
process moves to a next step.
[0143] Steps subsequent to step 207 are identical to those in the
fourth embodiment.
[0144] Thus, in accordance with the video network server according
to the seventh embodiment, specification by the user of the
allowable range of the quality of reproduced data is accepted by
the allowable quality specifying means, status of the network is
decided by the network status obtaining means and by the network
status decision means using traffic information indicating a degree
of congestion of the network, and the number of allowable terminals
can be changed by the parameter computing means and by the
parameter switching means depending on the allowable range by the
allowable quality specifying means and status of the network.
Therefore, the system can be constructed with flexibility in
accordance with demands from the user as follows: terminals which
the system may allow are increased previously with a quality of
data degraded in some degree, or the quality of data is further
improved with a number of terminals limited. In addition, when the
network is in poor status, that is, the network server is
overloaded, the number of allowable terminals is limited more
severely, thereby data transfer to the terminals supported at
present is not adversely affected by congestion of the network or
degraded response of the server. As a result, motion picture data
can be reproduced with reliability and qualities of reproduced data
are improved.
[0145] In the video network server according to the seventh
embodiment as in the fourth embodiment, when data is transferred
from the terminal and the data is recorded in a storage device of
the server, a number of allowable terminals can be set depending on
the situation following a procedure of a flow chart illustrated in
FIG. 21. As a result, reliability of recording and qualities of
recorded data are improved.
[0146] The allowable quality specifying means, the network status
obtaining means, the network status decision means, the network
server information obtaining means, the network server status
decision means, the parameter computing means, and the parameter
setting means may be held independently in each terminal, or may be
held on another network equipment as a separate apparatus.
[0147] Information which is obtained by the network status
obtaining means is not limited to the total number of packets and
information which is input to the allowable quality specifying
means is not limited to this illustration.
[0148] [Embodiment 8]
[0149] A video network server according to an eighth embodiment of
the present invention can change a number of allowable terminals
depending on an allowable range of qualities of reproduced data
specified by the user and status of the network server.
[0150] FIG. 22 is a block diagram illustrating a video network
server according to the eighth embodiment of the present invention.
In the figure, reference numeral 109 designates an allowable
quality specifying means to which the user inputs an allowable
range of a quality of reproduced data. The other reference
characters are identical to those in the fifth embodiment and will
not be discussed. FIG. 23 is a flow chart illustrating an operation
of the server of the eighth embodiment.
[0151] A description is given of an operation of a video network
server of the eighth embodiment with reference to FIGS. 22 and
23.
[0152] In step 201, it is decided whether information of the
allowable range of the quality of reproduced data is input to the
allowable quality specifying means 109 by the user or not. The
allowable range is identical to that in the seventh embodiment.
[0153] When it is decided that information is input to the
allowable quality specifying means 109, in step 202, the parameter
computing means 107 computes parameters on the basis of the input
information and the parameter setting means 108 sets the computed
parameters in the system. In step 201, when it is decided that the
allowable ranges is not specified by the user, the process moves to
a next step.
[0154] Steps subsequent to step 203 are identical to those in the
fifth embodiment.
[0155] Thus, in the video network server according to the eighth
embodiment, specification by the user of the allowable range of the
quality of reproduced data is accepted by the allowable quality
specifying means, information such as the response time of the
network server is obtained to decide its status by the network
server information obtaining means and by the network server status
decision means, a number of allowable terminals can be changed by
the parameter computing means and by the parameter switching means
depending on the allowable range by the allowable quality
specifying means and status of the network server. Therefore, the
system can be constructed with flexibility in accordance with
demands from the user with respect to the quality of data and the
number of allowable terminals. In addition, when the network server
is overloaded, the number of allowable terminals is limited more
severely to reduce load of the server, so that a service to
terminals supported at present is not adversely affected by the
load of the network server. As a result, motion picture data can be
reproduced with reliability and qualities of reproduced data are
improved.
[0156] In the video network server according to the eighth
embodiment as in the fourth embodiment, when data is transferred
from the terminal and the data is recorded in a storage device of
the server, the number of allowable terminals can be set depending
on the situation following a procedure of a flow chart illustrated
in FIG. 24. As a result, reliability of recording and qualities of
recorded data are improved.
[0157] The allowable quality specifying means, the network server
information obtaining means, the network server status decision
means, the parameter computing means, and the parameter setting
means may be held independently in each terminal, or may be held on
another network equipment as a separate apparatus.
[0158] Information which is obtained by the network server
information obtaining means is not limited to the response time and
information which is input to the allowable quality specifying
means is not limited to this illustration, either.
[0159] [Embodiment 9]
[0160] A video network server according to a ninth embodiment of
the present invention, a number of allowable terminals can be
changed depending on an allowable range of a quality of reproduced
data specified by the user, status of the network server, and
status of the network.
[0161] FIG. 25 is a block diagram illustrating the video network
server according to the ninth embodiment of the present invention.
In the figure, reference numeral 109 designates an allowable
quality specifying means to which the user inputs an allowable
range of a quality of reproduced data. The other reference
characters are identical to those in the sixth embodiment and will
not be discussed. FIG. 26 is a flow chart illustrating an operation
of the server of the ninth embodiment.
[0162] A description is given of an operation of a video network
server according to the ninth embodiment with reference to FIGS. 25
and 26.
[0163] In step 201, it is decided whether information of the
allowable range of the quality of reproduced data is input to the
allowable quality specifying means 109 by the user or not. The
allowable range is identical to that in the seventh embodiment.
[0164] When it is decided that information is input to the
allowable quality specifying means 109, in step 202 parameters are
computed by the parameter computing means 107 on the basis of input
information and the computed parameters are set in the system by
the parameter setting means 108. In step 201, when an allowable
range is not specified by the user, the process moves to a next
step.
[0165] Steps subsequent to step 203 are identical to those in the
sixth embodiment.
[0166] Thus, in the video network server according to the ninth
embodiment, specification by the user of the allowable range of the
quality of reproduced data is accepted by the allowable quality
specifying means, status of the network server is decided by the
network server information obtaining means and by the network
server status decision means, status of the network is decided by
the network status obtaining means and by the network status
decision means, the number of allowable terminals can be changed by
parameter computing means and by the parameter setting means
depending on the allowable range by the allowable quality
specifying means, status of the network server and status of the
network. Therefore, the system can be constructed with flexibility
with respect to the quality of data and the number of allowable
terminals in accordance with demands from the user. In addition,
when the network server is overloaded or the network is in poor
status, the number of allowable terminals is limited more severely,
thereby a affected by degraded response of the server. As a result,
motion picture data can be reproduced with reliability and
qualities of reproduced data are improved.
[0167] In the video network server according to the ninth
embodiment as in the fourth embodiment, when data is transferred
from the terminal and the data is recorded in a storage device of
the server, the number of allowable terminals can be set depending
on the situation following a procedure of a flow chart illustrated
in FIG. 27. As a result, reliability of recording and qualities of
recorded data are improved.
[0168] The allowable quality specifying means, the network status
obtaining means, the network status decision means, the network
server information obtaining means, the network server status
decision means, the parameter computing means, and the parameter
setting means may be held independently in each terminal, or may be
held on another network equipment as a separate apparatus.
[0169] Information which is obtained by the network status
obtaining means is not limited to the total number of packets ,
information which is obtained by the network server information
obtaining means is not limited to the response time, and
information which is input to the allowable quality specifying
means is not limited to this illustration.
[0170] [Embodiment 10]
[0171] A video network server according to a tenth embodiment of
the present invention can adjust time slot management in accordance
with a required data transfer rate.
[0172] FIG. 28 is a block diagram illustrating a server according
to the tenth embodiment.
[0173] In the figure, reference numeral 301 designates a network
interface through which the video network server is connected to a
network. A data storage means 303 is for storing data of the video
network server. A buffer memory 304 is for temporarily storing data
which is read from the data storage means 303. A data information
obtaining means 306 is for obtaining information such as a required
transfer rate of data which is requested by the terminal. A
parameter computing means 305 is for deciding whether it is
possible to read data in half of a time slot size allocated to a
terminal in a time slot period or not, on the basis of the required
transfer rate which is obtained by the data information obtaining
means 306, allocating one time slot size for reading data to the
terminal every two periods of a time slot period, and allocating
remaining one time slot size in a time slot period which has not
been allocated, for another terminal, when it is decided that it is
possible to read the data in half of the time slot size. A data
prereading means 302 is for reading the data which is requested by
the terminal from the data storage means 303 and outputting the
data to the buffer memory 304. A data feeding means 308 is for
feeding the data which is output to the buffer memory 304 to the
terminal.
[0174] FIG. 29 is a flow chart illustrating an operation of the
server of the tenth embodiment. FIG. 30 is a diagram illustrating
parameters of the system which is preset in the server of the tenth
embodiment. FIGS. 31 to 33 are diagrams illustrating time slot
management in an operation of the server of the tenth
embodiment.
[0175] A description is given of an operation of the video network
server according to the tenth embodiment of the present invention
with reference to FIGS. 28 to 33.
[0176] When data request is issued from the terminal to the server,
in step 401, the data information obtaining means 306 obtains
information such as a required transfer rate of the data. The
required transfer rate is a transfer rate required to reproduce
data continuously in transferring data such as a motion picture.
For example, the required transfer rate of data which is requested
by a terminal A1 is 1.5 Mbps. In step 402, the parameter computing
means 305 compares the obtained information with parameters of the
system at present. In this case, parameters at present are
illustrated in FIG. 30. These parameters are set indicating the
following. If data which is requested by n terminals is read
continuously for a time of the time slot size (1333/n msec)
allocated for the each terminal per 1333 msec of the time slot
period, the data can be transferred to each terminal at a transfer
rate of 3.0 Mbps, so that it follows that data of required transfer
rate which is not higher than 3.0 Mbps can be reproduced
continuously at each terminal. In this case, parameters are set so
that request of data of 3.0 Mbps may be issued from n terminals per
period 1333 msec at the same time. FIG. 31 is a diagram
illustrating time slot management in reading data which is supplied
to n terminals, where a lateral axis represents a time.
[0177] In step 402, a transfer rate of data which is requested by
the terminal A1 is 1.5 Mbps, which is compared with 3.0 Mbps (a
transfer rate of the system at present), so that it is decided that
the data can be read in half of the time slot size which is
allocated for the terminal A1 or less, and the parameter computing
means 305 computes parameters on assumption that data is read for
the terminal A1 every two periods. In step 403, time distribution
in reading data is changed from one shown in FIG. 31 to one shown
in FIG. 32, so that there is a free time of one time slot size
every two periods. That is, in case of data which can be read every
two periods, i.e., at a required transfer rate which is not higher
than 1.5 Mbps, there is a free time for reading data for a
terminal.
[0178] When a request is issued from a (n+1)th terminal (a number
of terminals which the system may allow is precomputed to be "n")
in step 404, a free time interval of one time slot size is
allocated for the terminal which issued the request in step 405 if
a transfer rate of the terminal which issued the request is not
higher than 1.5 Mbps. Time distribution at this time is shown in
FIG. 33.
[0179] In step 406, it is checked whether a data request is being
issued by the terminal A1 or not. As long as the data request is
being issued from the terminal A1, steps 404 to 406 are
repeated.
[0180] For a time of one time slot size every two periods of the
time slot period which is allocated for the terminal A1, the data
prereading means 302 reads the data which is requested by the
terminal A1 from the data storage means 303 to the buffer memory
304, and the data feeding means 308 fetches data from the buffer
memory 304 and feeds the data through the network interface 301,
via a network, and to the terminal A1.
[0181] The video network server of the tenth embodiment adjusts
allocating time for a terminal by changing the time slot management
in accordance with a transfer rate which is requested described
above.
[0182] Thus, in accordance with the video network server of the
tenth embodiment, the data information obtaining means obtains the
required transfer rate of the data which is requested by the
terminal; and the parameter computing means compares the obtained
required transfer rate with the transfer rate which is assumed by
the system; in case of data of required transfer rate which is not
higher than half of the assumed data transfer rate, computes
parameters so that one time slot size is allocated for transferring
the data every two periods of the time slot period and remaining
one time slot size is allocated for another terminal every two
periods by changing time slot management. Therefore, it is possible
to operate the system effectively without free time in a time slot
and without using read time.
[0183] In the video network server of the tenth embodiment, since
the transfer rate of the data which is requested by the terminal is
half as high as the assumed transfer rate, a given time interval is
allocated every two periods. Alternatively, the given time interval
may be allocated every three periods and a transfer rate of a
plurality of times may coexist. In this case, the parameter
computing means 305 must decide optimum allocation of time interval
so that there is free time as little as possible.
[0184] In the tenth embodiment, although time distribution for each
terminal is performed sequentially in numerical order of terminal
such as A1 to An, it is not necessary to perform this in specified
order.
[0185] It should be noted that parameters preset in the system
shown in FIG. 30 are by way of example only and are not limited to
these types, nether is a number. Having described the terminal A1
in the tenth embodiment, process is performed for the other
terminals A2 to An concurrently with terminal A1.
* * * * *