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Claims  |
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What is claimed is:
1. A multimedia communication apparatus for communicating with a
destination apparatus, said communication apparatus and the destination
apparatus each having a respective capability to transmit and receive data
within predetermined limits, and each being operable in any one of a
respective plurality of communication modes for transmitting and receiving
data within the limits set by the respective capability, wherein in each
communication mode, at least one channel for data communication is set,
said communication apparatus comprising:
data communication means for communicating first and second data to the
destination apparatus, the first data being a different kind of data from
the second data;
determination means for determining which of the communication modes can be
used to communicate data between said communication apparatus and the
destination apparatus, to designate one communication mode that can be so
used, and to set the communication apparatus to operate in the designated
communication mode, the determination being made in accordance with the
capability of the destination apparatus and the capability of said
communication apparatus;
setting means connected to said determination means and responsive to the
determination and the designation of the determination means for setting
at least a first channel having a structure defining how data is
communicated therein between said communication apparatus and the
destination apparatus; and
comparison means connected to said determination means and said setting
means for deriving a transmission rate at which said first data can be
communicated within the first channel in accordance with the structure of
the first channel, and for comparing the derived transmission rate with a
defined value indicative of a sufficient transmission rate of said first
data within the first channel,
wherein said setting means does not set a second channel between said
communication apparatus and the destination apparatus, even if a second
channel is settable within the designated communication mode, when the
derived transmission rate is greater than the defined value.
2. An apparatus according to claim 1, wherein the first data comprises
image data and the second data comprises voice data, and wherein said data
communication means communicates the image data and the voice data while
multiplexing these data.
3. An apparatus according to claim 1, wherein said setting means sets the
second channel if the derived transmission rate is smaller than the
defined value and if the second channel is settable.
4. A multimedia communication apparatus for communicating with a
destination apparatus, said communication apparatus and the destination
apparatus each having a respective capability to transmit and receive data
within predetermined limits, and each being operable in any one of a
respective plurality of communication modes for transmitting and receiving
data within the limits set by the respective capability, wherein in each
communication mode, at least one channel for data communication is set,
said communication apparatus comprising:
data communication means for communicating first and second data to the
destination apparatus, the first data being a different kind of data from
the second data;
first setting means for setting a first channel having a structure defining
how data is to be communicated therein between said communication
apparatus and the destination apparatus, and for enabling communication of
the second data within the first channel;
input means operable by a user for inputting an instruction to start
transmission of the first data within the first channel; and
means for deriving a transmission rate at which the first data can be
communicated within the first channel in accordance with the structure of
the first channel and the instruction input from said input means,
wherein said data communication means communicates the first data in
accordance with the derived transmission rate after the input of the
instruction to start communication of the first data.
5. An apparatus according to claim 4, wherein the first data comprises
video data and the second data comprises voice data, and wherein said data
communication means communicates the video data and the voice data while
multiplexing these data.
6. An apparatus according to claim 4, further comprising determination
means for determining which of the communication modes can be used to
communicate data between said communication apparatus and the destination
apparatus, to designate one communication mode that can be so used, and to
set the communication apparatus to operate in the designated communication
mode, the determination being made in accordance with the capability of
the destination apparatus and the capability of said communication
apparatus, and wherein said deriving means derives the derived
transmission rate in accordance with the determination of said
determination means.
7. An apparatus according to claim 4, further comprising comparison means
for comparing the derived transmission rate with a defined value
indicative of a sufficient transmission rate of said first data within the
first channel, and second setting means for setting a second channel
between said communication apparatus and the destination apparatus if the
derived transmission rate is smaller than the defined value, and if the
second channel is settable.
8. A multimedia communication apparatus for communicating with a
destination apparatus, said communication apparatus and the destination
apparatus each having a respective capability to transmit and receive data
within predetermined limits, and each being operable in any one of a
respective plurality of communication modes for transmitting and receiving
data within the limits set by the respective capability, wherein in each
communication mode, at least one channel for data communication is set,
said communication apparatus comprising:
data communication means for communicating first and second data to the
destination apparatus, the first data being a different kind of data from
the second data;
first determination means for determining whether or not turning-off of
communication of the first data has been selected during communication of
the first and second data by said data communication means in a selected
one of the communication modes, said communication apparatus turning-off
communication of the first data in response to the selection;
second determination means for determining whether or not a channel for
communicating data in the selected communication mode has become vacant by
the turning-off of the communication of the first data; and
releasing means for, if said second determination means has determined that
a channel has become vacant, releasing the vacant channel from use.
9. An apparatus according to claim 8, wherein the first data comprises
video data and the second data comprises voice data, and wherein said data
communication means communicates the video data and the voice data while
multiplexing these data.
10. An apparatus according to claim 8, further comprising third
determination means for selecting the selected communication mode by
determining which of the communication modes can be used to communicate
data between said communication apparatus and the destination apparatus,
to designate one communication mode that can be so used, and to set the
communication apparatus to operate in the designated communication mode,
the determination being made in accordance with the capability of the
destination apparatus and the capability of said communication apparatus.
11. A multimedia communication apparatus for communicating with a
destination apparatus, said communication apparatus and the destination
apparatus each being operable in any one of a plurality of communication
modes for data communication, comprising:
data communication means for communicating first and second data to the
destination apparatus, the first data being a different kind of data from
the second data;
determination means for determining whether said communication apparatus is
at a calling side for transmitting data or at a reception side for
receiving data;
first setting means for setting said communication apparatus to operate in
a first one of the plurality of communication modes which allows
transmission of the first and second data by said data communication means
if said communication apparatus is at the calling side;
second setting means for setting said communication apparatus to operate in
a second one of the plurality of communication modes which allows
transmission of the first data by said data communication means if said
communication apparatus is at the reception side; and
third setting means for setting said communication apparatus to operate in
a third one of the plurality of communication modes which allows
transmission of the first and second data if transmission of the first
data is selected according to an instruction input by an operator after
the second mode has been set by said second setting means.
12. An apparatus according to claim 11, wherein the first data comprises
video data and the second data comprises voice data, and wherein said data
communication means communicates the video data and the voice data while
multiplexing these data.
13. A multimedia communication apparatus for communicating with a
destination apparatus, said communication apparatus and the destination
apparatus each having a respective capability to transmit and receive data
within predetermined limits, and each being operable in any one of a
respective plurality of communication modes for transmitting and receiving
data within the limits set by the respective capability, comprising:
data communication means for communicating first and second data to the
destination apparatus, the first data being a different kind of data from
the second data;
selection means for selecting turning-on or turning-off of transmission of
the first data to the destination apparatus, said selecting means having
an on-state in which it can make a selection and an off-state it which it
cannot make a selection;
detection means connected to said selection means for detecting a start of
transmission;
setting means for setting said selection means to the on-state when said
detection means has detected the start of the transmission;
determination means for determining which of the communication modes can be
used to communicate data between said communication apparatus and the
destination apparatus, to designate one communication mode that can be so
used, and to set the communication apparatus to operate in the designated
communication mode, the determination being made in accordance with the
capability of the destination apparatus and the capability of said
communication apparatus; and
control means for keeping said selection means in the on-state up until a
time when said determination means designates a communication mode.
14. An apparatus according to claim 13, wherein the first data comprises
video data and the second data comprises voice data, and wherein said data
communication means communicates the video data and the voice data while
multiplexing these data. |
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Claims |
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Description |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a multimedia communication apparatus represented
by an AV (audiovisual) communication apparatus, such as a video telephone
apparatus, a television meeting system or the like, in which mutual
communication can be performed by multiplexing multimedia information
comprising voice information, video information, data and the like.
2. Description of the Related Art
Recently, communication services via an ISDN (integrated services digital
network) have started to be practically used, and AV services, such as
video telephones, television meeting systems and the like, using such a
digital network have attracted notice. Service provisions for AV services,
protocol provisions, multimedia multiplex frame structure provisions,
encoding methods of moving-picture information and the like have been
announced as CCITT (Comite Consulatif International Telegraphique et
Telephonique)'s recommendations H. 320, H. 242, H. 221, H. 230, H. 261,
and the like. In H. 221, frame structures in AV services on channels
having bit rates of 64 kbps (kilobits per second)-1920 kbps are provided.
FIG. 12 shows the frame structure in H. 221 on a single channel having a
bit rate of 64 kbps. In FIG. 12, numerals 1 -8 indicated in the abscissa
represent bit numbers, and numerals 1-80 indicated in the ordinate
represent octet numbers. One frame comprises 80 octets. In FIG. 12, frame
synchronization, multiframe synchronization, the function of monitoring
communication quality, notification of alarm information, and the like are
controlled by FAS's (frame synchronizing signals).
FIG. 13 is a diagram showing the bit assignment of FAS's in 1 multiframe=8
submultiframes (1 submultiframe=2 frames). BAS's (bit-rate allocation
signals) assign the capability of terminals and actual allocation of bit
rates to respective media within frames, and perform various kinds of
controls and notification. As shown in FIG.2, BAS's are transmitted in
even frames, and corresponding error-correcting bits are transmitted in
odd frames.
In H. 242, communication procedures, such as a capability-information
exchange sequence, a mode switching sequence and the like using BAS's on
in-channel between AV terminals are provided. In H. 320, system aspects
for the entirety of AV services are provided. In H. 230,
transmission-frame synchronization or various kinds of controls and
notification requiring an urgent response are provided as additional
information to functions necessary for AV services. In H. 261, methods of
encoding/decoding moving-picture information in bit rates of p.times.64
kbps (p=1-30) are provided.
FIG. 14 shows a basic sequence in performing multimedia communication of
images, voice, data (all kinds of user's information other than images and
voice) according to the above-described recommendations.
First, by starting a multimedia communication apparatus which is intended
to start communication (hereinafter termed a calling-side apparatus), a
first channel is established in step 141. In the case of the ISDN, this
corresponds to a call-setting sequence in the D-channel- Subsequently, in
step 142, frame synchronization is established by retrieval/detection of
an FAS and transmission/detection of A-bit=0 on the channel set in step
141 (corresponding to the B-channel, the H-channel or the like in the
ISDN).
After establishing synchronization, in step 143, the capability of the
communication partner's apparatus is determined by a
capability-information exchange sequence by transmission, reception and
detection of a capability BAS. Subsequently, in step 144, multiplex
allocation of multi-media information on the first channel is determined,
a mode switching sequence by transmission/reception of a BAS command is
performed, and multimedia-information multiplex communication is started.
In practice, there is a case in which only voice information can be
communicated, or a case in which only voice information is communicated
until an additional channel is established.
The process then proceeds to step 145, and further to step 146 if the
communication partner's apparatus has a capability of providing an
additional channel, and the additional channel is established.
Subsequently, in step 147, processing for establishing frame
synchronization and multiframe synchronization, and synchronization with
the first channel, is performed utilizing retrieval/detection of an FAS in
the additional channel, and an A-bit. The process then returns to step
145, where it is determined whether or not an additional connection is
further required.
If an additional channel is not required, in step 148, an operational mode
suitable for the utilization of all the channels is determined, a mode
switching sequence by transmission/reception of a BAS command is
performed, and multimedia multiplex communication is performed.
There is a case in which the mode switching sequence by a BAS command to be
performed in step 148 is performed immediately after step 144, ant a mode
switching sequence is performed every time a channel is added whenever
necessary. In the above-described recommendations, however, there is no
particular provision about whether the start of an operation for
establishing an additional channel must be performed by the calling-side
apparatus or by the reception-side apparatus, and what a specific trigger
for that operation is. Furthermore, there is no particular provision
either about whether an additional channel must be unconditionally
established if each of the two apparatuses has the capability of providing
an additional channel, or whether an operation for establishing an
additional channel must be started by some particular trigger.
In the above-described conventional approach, however, in an apparatus
which unconditionally sets an additional channel after it has been
determined that the communication partner's apparatus also has the
capability of providing an additional channel by a capability-information
exchange sequence, while the user need not intentionally perform an
operation to set an additional channel, an additional channel is
automatically set even if it is unnecessary, and therefore an unnecessary
network tariff is charged without the user acknowledging it.
In an apparatus in which an additional channel is always started by an
operation of the user, the user will know he must always be alert to the
need for this operation, and the operation itself can be troublesome.
In addition, in the conventional approach, sufficient care has not yet been
taken &bout when and in which conditions video information must be
transmitted. Accordingly, transmission is unconditionally started even if
a transmission rate allocatable to video information is insufficient, or
an additional channel allowed by a capability-information exchange
sequence is unconditionally set. As a result, the additional channel is in
a vacant state because transmission of video information is not
immediately started, whereby an unnecessary network tariff is charged.
Furthermore, in the transmission of video information, a trigger to start
transmission at the calling side and the reception side is not considered.
Hence, it may happen that transmission of video information is immediately
started also at the reception side, or although it is possible to change
the setting of whether or not video information must be transmitted, the
setting cannot be easily changed.
SUMMARY OF THE INVENTION
It is an object of the present invention to remove the above-described
problems in the prior art.
It is a further object of the present invention to provide a multimedia
communication apparatus which can prevent an unnecessary use of a network.
It is a still further object of the present invention to provide a
multimedia communication apparatus which can automatically set a channel
without wastefully using a network by automatically setting the minimum
number of channels necessary for communicating video information, and not
setting an unnecessary additional channel,
It is still another object of the present invention to provide a multimedia
communication apparatus which can prevent a unnecessary use of a network
due to setting an unnecessary channel when video information is not
transmitted by determining whether or not an automatic setting of an
additional channel must be started after comparing a transmission rate
allocatable for video information in a channel at a time period when the
start of video transmission is instructed by an operation of the user with
a certain defined value, and executing the setting if the result of the
determination is affirmative.
It is a still further object of the present invention to provide a
multimedia communication apparatus which can determine whether or not a
channel in a "vacant" state has been generated when an operation of the
user has instructed the stop of transmission of video information, and
which can automatically release a vacant channel when the channel has
entered a "vacant" state.
It is still another object of the present invention to provide a multimedia
communication apparatus which can mitigate a negative reaction of the user
against an instant response to the reception of video telephone at the
reception side by automatically turning on a trigger to start transmission
of video information according to the start of a calling operation at the
calling side, and not automatically starting transmission of video
information before an operation of the user at the reception side.
These and other objects, advantages and features of the present invention
will become more apparent from the following detailed description of the
preferred embodiments taken in conjuction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram showing the configuration of a multimedia
communication apparatus according to a first embodiment of the present
invention;
FIG. 2 is a plan view showing a specific example of the operation unit of
the apparatus shown in FIG. 1;
FIG. 3 is a flowchart showing a control-operation procedure of the
apparatus in the first embodiment;
FIGS. 4(a) through 7 are diagrams showing the structure of multiplex frames
indicated in the CCITT's recommendation draft H. 221;
FIG. 8 is a flowchart showing a control-operation procedure in a second
embodiment of the present invention;
FIG. 9 is a flowchart showing a control-operation procedure in a third
embodiment of the present invention;
FIG. 10 is a flowchart showing a control-operation procedure in a fourth
embodiment of the present invention;
FIG. 11 is a flowchart showing a control-operation procedure in a fifth
embodiment of the present invention;
FIG. 12 is a diagram showing the configuration of a frame indicated in the
CCITT's recommendation draft H. 221;
FIG. 13 is a diagram showing bit allocation for FAS's and BAS's within a
multiframe; and
FIG. 14 is a flowchart showing a control-operation procedure of a
conventional multimedia communication apparatus.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
An explanation will now be provided of preferred embodiments of the present
invention with reference to the drawings.
First Embodiment
FIG. 1 is a block diagram showing the configuration of a multimedia
communication apparatus according to a first embodiment of the present
invention. In FIG. 1, a handset (a transmitter-receiver) 1 serves as a
voice input/output means of the present apparatus. A microphone 2 serves
as a voice input means of the apparatus. A speaker 3 serves as a voice
output means of the apparatus. The handset 1, the microphone 2 and the
speaker 3 are connected to a voice interface unit 4.
The voice interface unit 4 performs, according to an instruction from a
system control unit 14 (to be described later), for example, stitching
processing for switching the operations of the handset 1, the microphone 2
and the speaker 3, on-hook/off-hook detection processing for detecting
whether the handset 1 is in an on-hook state or in an off-hook state, echo
cancel processing for removing an echo when the microphone 2 and the
speaker 3 are operated, and tone generation processing for generating a
dial tone, a ringing tone, a busy tone, a call-reception tone or the like.
The voice interface unit 4 is connected to a voice encoding/decoding unit
5.
According to an instruction from the system control unit 14, the voice
encoding/decoding unit 5 encodes a voice signal to be transmitted, or
decodes a received voice signal in accordance with a voice-signal
encoding/decoding rithm, such as 64 kbps PCM (pulse-code modulation)
A-law, 64 kbps PCM .mu.-law, 64 kbps/56 kbps/48 kbps SB-ADPCM (adaptive
differential pulse-code modulation), 32 kbps ADPCM, 16 kbps (for example,
APC-AB), 8 kbps or the like.
A video camera 6 serves as an image input means of the apparatus, and
inputs an image of the user or the like. A picture camera 7 also serves as
an image input means of the apparatus, and inputs a picture, a drawing or
the like. An image display unit 8 displays an input image from the video
camera 6 or the picture camera 7, a received image from the communication
partner, an operational picture frame or the like. The video camera 6, the
picture camera 7 and the image display unit 8 are connected to a video
interface unit 9.
According to an instruction from the system control unit 14, the video
interface unit 9 performs switching processing between the image input
means, display switching processing of the inn image, the received image
and the operational picture frame on the image display unit 8,
video-signal synthesis processing for displaying the above-described
images on the image display unit 8 while dividing them, or the like. The
video interface unit 9 is connected to a video encoding/decoding unit (an
image coded unit) 10.
The video encoding/decoding unit 10 encodes a video signal to be
transmitted, and decodes a received video signal according to the CCITT's
recommendation draft "H. 261".
A data terminal 11 performs transmission/reception of data, and is
connected to a data interface unit 12. The data interface unit 12
transmits data to be transmitted received from the data terminal 11 and
the system control unit 14 to a multiplexing/separation unit 15 (to be
described later), and also transmits received data to the data terminal 11
or the system control unit 14.
An operation unit 13 comprises a keyboard used for inputting control
information for controlling the entire apparatus, a touch panel and the
like. The voice interface unit 4, the voice encoding/decoding unit 5, the
video interface unit 9, the video encoding/decoding unit 10, the data
interface unit 12 and the operation unit 13 are connected to the system
control unit 14.
The system control unit 14 includes a CPU (central processing unit), a ROM
(read-only memory), a RAM (random access memory), an auxiliary storage
unit and the like. The system control unit 14, for example, monitors the
states of the respective units to control the entire apparatus, calculates
transmission speeds allocated to respective media according to input
control information, the state of the utilized network, and the like,
forms the operational/display picture frame in accordance with the
determination, the control and the state of the final mode, and executes
application programs.
The voice encoding/decoding unit 5, the video encoding/decoding unit L0 and
the data interface 12 are connected to the multiplexing/separation unit
15. The multiplexing/separation unit 15 multiplexes voice signals from the
voice encoding/decoding unit 5, video signals from the video
encoding/decoding unit 10, data from the data interface unit 12, data from
the system control unit 14, and control information according to the
CCITT's recommendation drafts "H. 221", "H. 242" and the like, in units of
a transmission frame in accordance with the CCITT's recommendation draft
"H. 221", divides the reception frame into respective constituent media,
and transmits the resultant data to the respective units. The
multiplexing/separation unit 15 is connected to the system control unit 14
and a network interface unit 16.
The network interface unit 16 controls the network in accordance with an
ISDN user network interface. A storage unit 17 stores various kinds of
control information, and is connected to the system control unit 14.
FIG. 2 is a diagram showing a specific example of the operation unit 13. In
FIG. 2, a display unit (display means) 20, comprising an LED
(light-emitting diode) or the like, displays various kinds of information,
such as input information for operations, various kinds of received
information, and the like. A video transmission key 21 instructs the
start/stop of transmission of video information. Various kinds of function
keys 22 instruct registration, change, execution and control of additional
services of the apparatus. There are also shown a monitoring-display
switching key 23, a voice-output-volume adjustment key 24, ten keys 25 for
dial inputs, a one-touch dial key, and a switching key 27 for switching
between the microphone and speaker and the handset.
Next, the operation of the multimedia communication apparatus of the
present invention having the above-described configuration will be
explained in detail with reference to the flowchart shown in FIG. 3.
First, in step 301, a first channel is established. More specifically, in
the case of the ISDN, the first channel is established on the D-channel by
the reception of a CONN (notifying that the called person has responded
(offhook)) message for the transmission of a SETUP (request of call
setting) by a D-channel call control, and by the reply of a CONN-ACK
(confirmation of the CONN).
Next, in step 302, in order to establish a channel on in-channel,
synchronization by the H. 221 frame is first established. If the frame
synchronization has been mutually established, the process proceeds to
step 303, where a capability-information exchange sequence by the
transmission/reception of a capability BAS is executed. If the
capability-information exchange sequence has been completed, the process
proceeds to step 304, where a settable communication mode is determined
according to the result of a comparison between the capability of the
user's own apparatus and the capability of the communication partner's
apparatus.
For example, as a first case, if it is assumed that the transfer-rate
capability=2B, the voice capability=16 kbps/A-law/.mu.-law, and the video
capability=H. 261 CIF & QCIF as common capabilities, the transfer rate=2B,
video =ON, and voice=16 kbps/A-law/.mu.-law are selectable as a common
communication mode.
Which voice mode must be selected differs according to whether priority
must be given to voice quality or picture quality. If priority must be
given to picture quality, it becomes possible to perform multiplexing of
multimedia information, as shown in FIGS. 4(a) and 4(b).
In step 304, the allocatable rate for video information in multimedia
information multiplexing on the first channel is calculated. In this case,
46.4 kbps when voice information of 16 kbps is selected becomes the
maximum allocatable rate when the video information is multiplexed with
voice information, as shown in FIG. 5.
For example, as a second case, if it is assumed that the tranfer-rate
capability=2B, the voice capability=A-law/.mu.-law, and the video
capability=H. 261 CIF/QCIF as common capabilities, the transfer rate=2B,
video=ON, and voice=A-law/.mu.-law are selectable as a common
communication mode.
If multiplexing of multimedia information is performed at that time, a
communication mode as shown in FIGS. 6(a) and 6(b) is obtained. When only
the first channel is used, only the mode shown in FIG. 7 is selectable.
The allocatable rate for video information at that time is 6.4 kbps.
In step 305, the allocatable rate for video information calculated in step
304 is compared with a defined value X. If the defined value X is assumed
to be 30 kbps, the allocatable rate for video information in the first
case is greater than the defined value X, and the allocatable rate for
video information in the second case is smaller than the defined value X.
If the allocatable rate for video information is smaller than the defined
value X, the process proceeds to step 308, where it is determined whether
or not an additional channel is settable.
If the transfer-rate capability still permits an additional channel, the
process proceeds to step 307, where an additional channel is established.
In step 307, as in step 301, call-setting in out-channel is performed. In
the case of the ISDN, the same setting as in step 301 by D-channel
call-control is performed. Subsequently, in step 308, synchronization by
the H. 221 frame on in-channel is established as well as multiframe
synchronization. The process then proceeds to step 309, where the
allocatable rate for video information on a plurality of established
channels is calculated, and the process returns to step 305.
For example, in the above-described second case, the video-information rate
becomes 68.8 (62.4+6.4) kbps, as shown in FIGS. 6(a) and 6(b).
If it has been determined in step 305 that the allocatable rate for video
information is greater than the defined value X, the process proceeds to
step 310, where the final transmission mode is determined. In the next
step 311, a BAS command is transmitted, and transmission according to the
corresponding transmission mode is actually started by switching the
transmission mode. The control operation is thus terminated.
If it has been determined in step 306 that an additional channel cannot be
set, the process proceeds to step 310. At that time, whether a mode of
transmitting video information is selected even if the allocatable rate
for video information is less than the defined value X, or a mode of not
transmitting video information is selected as the final transmission mode
depends on the determination of each apparatus or the determination of the
user.
As explained above, according to the multimedia communication apparatus of
the first embodiment of the present invention, even if an additional
channel is determined to be settable by determining the capability of the
communication partner's apparatus according to a capability-information
exchange sequence, the operation of setting an additional channel is not
unconditionally started. The transmission rate allocatable for video
information when multiplexing of voice and video information using only
the first channel is performed is calculated, and it is determined whether
or not the calculated value is greater than the defined value. If the
calculated value is smaller than the defined value and an additional
channel is settable, an operation of setting the additional channel is
started. If the calculated value is greater than the defined value, it is
determined that the channel is sufficient for the intended transmission of
video information, and an operation of setting an additional channel is
not activated. Thus, only a channel which will secure at least the defined
value is automatically set, and an unnecessary additional channel is not
set. It is thereby possible to prevent unnecessary use of the network
caused by unconditional setting of an additional channel.
Second Embodiment
Next, an explanation will be provided of the operation of a multimedia
communication apparatus according to a second embodiment of the present
invention with reference to the flowchart shown in FIG. 8. Processing from
step 801 to step 803 is the same as the processing from step 301 to step
303 shown in FIG. 3. Subsequently, in step 804, a mode of transmitting
only voice information is set. In step 805, the process waits until the
start of transmission of video information is instructed by an operation
of the user.
When the start of transmission of video information has been instructed,
the process proceeds to step 806, where the allocatable rate for video
information when multiplexing of voice and video information is performed
on the first channel is calculated. Subsequently, in step 807, the
allocatable rate for video information calculated in step 806 is compared
with the defined value X. If the calculated value is less than the defined
value, the process proceeds to step 808. Processing in steps 808-811 is
the same as the processing in steps 306-309 shown in FIG. 3.
If the calculated value is greater than the defined value in step 807, and
if it has been determined that an additional channel cannot be set in step
808, the process proceeds to step 812 and step 813. Processing in steps
812 and 813 is the same as the processing in steps 310 and 311 shown in
FIG. 3.
As described above, according to the multimedia communication apparatus of
the second embodiment of the present invention, when setting of a mode of
not unconditionally starting transmission of video information is
selected, an operation of setting an additional channel is not
automatically started even if the additional channel is settable. When the
start of transmission of video information has been instructed by an
operation of the user, the allocatable transmission rate for video
information in the channel at that time period is compared with a certain
defined value, and it is determined whether or not automatic setting of an
additional channel must be started, and the setting is executed if the
result of the determination is affirmative. It is thereby possible to
prevent unnecessary use of the network caused by setting an unnecessary
channel when video information is not transmitted.
Third Embodiment
Next, an explanation will be provided of a multimedia communication
apparatus according to a third embodiment of the present invention with
reference to the flowchart shown in FIG. 9.
First, if a transmission operation is performed in a multimedia-information
multiplex communication mode including image information in step 901,
whether or not an instruction to stop (turn off) the transmission of image
information has been instructed is monitored in step 902. When an
instruction to stop the transmission of video information has been
performed by an operation of the user, the process proceeds to step 903,
where a mode switching sequence including a BAS command to turn off the
transmission of video information is executed.
Subsequently, in step 904, it is determined whether the user's own
apparatus is at the calling side or at the reception side. If the user's
own apparatus is at the calling side, the process proceeds to step 905,
where it is determined whether or not a channel in a "vacant" state has
been generated in a transmission mode from the user's own apparatus
according to the mode switching sequence in the above-described step 903.
For example, in the states shown in FIGS. 4(a) and 4(b) or FIGS. 6(a) and
6(b), if the transmission of video information is turned off, the second
channel enters a "vacant" state. On the other hand, in the state shown in
FIG. 5, the first channel does not enter a "vacant" state even if the
transmission of video information is turned off.
If a channel in a "vacant" state has been generated, the process proceeds
to step 906. In step 906, by checking the reception mode, it is determined
whether or not the channel in a "vacant" state is used in the reception
mode, that is, used in the transmission mode of the communication
partner's apparatus while the transmission operation is performed in the
multimedia-information multiplex transmission mode including the
transmission of video information. If the result of the determination is
affirmative, the process proceeds to step 907. In step 907, a procedure of
forcedly setting the mode 0 defined in H. 242 is executed, and both
transmission and reception are switched to a mode of communicating only
voice information using only the first channel.
The process then proceeds to step 908, where the unnecessary channel which
enters a "vacant" state when the transmission of video information is
turned off determined in the above-described step 905 is released. More
specifically, in the ISDN, according to the D-channel call-control, the
channel is decreased in the sequence of the procedure of DISC (request for
call-release) message, REL (notification of the completion of
disconnection of the channel, and request of release of the called number)
message, REL-COMP (release of the channel, and notification of the
completion of release of the called number) message and the like. The
process then proceeds to step 909, where the capability-information
exchange sequence is executed again, and the process proceeds to step 910.
In step 910, a mode switching sequence, in which the calling side selects
the transmission mode corresponding to the mode switching sequence
executed in the above-described step 903, and the reception side selects a
suitable transmission mode corresponding to the number of channels at that
time period, is executed, and thus the control operation is terminated.
If the user's own apparatus is at the reception side in step 904, or a
"vacant" channel is not generated in step 905, the control operation is
terminated without executing the following steps. If the channel is in a
"vacant" state even in the reception mode in the above-described step 906,
the process proceeds to step 911, where the channel in a "vacant" state is
released, and thus the control operation is terminated.
According to the multimedia communication apparatus of the third embodiment
of the present invention, when the stoppage of transmission of video
information has been instructed by an operation of the user, it is
determined whether or not a channel in a "vacant" state has been generated
in the transmission mode from the corresponding apparatus. If the result
of the determination is affirmative, it is determined whether the channel
in a "vacant" state is at the calling side or at the reception side, or at
the side charged with a tariff or at the side not charged with a tariff.
The corresponding channel is automatically released at the generation of
the channel in a "vacant" state at the calling side or at the side charged
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