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CROSS-REFERENCE TO RELATED COPENDING APPLICATIONS:
1. Ser. No. 07/186,168; filed 4/26/88; now U.S. Pat. No. 4,902,989
2. Ser. No. 07/191,011; filed 5/6/88; now abandoned.
This invention concerns control of a considerable number of units of video
apparatus from a single control location, as is particularly useful in a
television broadcasting or recording studio or center.
A method is known from the periodical "Technische Mitteilungen des RFZ",
Heft 3/1985, pgs. 49-54, for controlling video technical installations in
which control information is passed on over so-called parallel interfaces
through branches of a tree structure of communication. Control according
to this known method utilizes a great deal of circuitry and switching and
requires a multiplicity of control lines or cables. Furthermore, control
systems of that type are not easily adaptable to other apparatus
configurations with different functions.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a method for
controlling apparatus units in modern video technology in considerable
numbers or aggregates which is more flexible than what has heretofore been
used and which is adaptable to rearrangement of configurations of
aggregates of apparatus.
Briefly a number of apparatus units are combined to form a single aggregate
or cluster of equipment unit and are connected together by a serial
digital signal communication bus, each apparatus unit of the aggregate
being provided with a standard interface which is adjustable and is
capable of sending and receiving data telegrams, and preferably with a
number of such interfaces. Each apparatus unit of the cluster has an
intra-cluster address in the form, for example, of a 4-bit designation (up
to 16 units of apparatus), or a 5-bit or 6-bit address for a larger
cluster. This has the advantage that many apparatus units, for example
magnetic recording devices or film scanners selectable within one control
group can be operated simultaneously. The transmission of control
information takes place over a single communication channel or path. The
individual apparatus units will then not interfere with each other's
behavior. This universal control connection can be provided for various
tasks outside of an individual apparatus unit, so that a number of
apparatus units can be collected together in a closed control system in
which access can be obtained to all functions of an individual apparatus.
For example an operating or control desk can be associated with a
particular one of a number of magnetic recording equipments by dynamically
configuring addresses, after which, leaving that equipment working, it can
be associated with another, and so on. It is no longer necessary, then, to
make a modification of fixed apparatus addresses conforming to a standard
protocol such as that of IEEE Standard 802.3.
BRIEF DESCRIPTION OF THE DRAWINGS
Further details and advantages of the invention are explained below by way
of illustrative embodiment with reference to the annexed drawings, in
which:
FIG. 1 is a circuit block diagram of three video cassette recorders having
a common control system;
FIG. 2 is a schematic diagram for illustrating control of two video
cassette recorders in an editing operation in the control of a single
keyboard, in accordance with the invention, and
FIG. 3 is a flow diagram illustrating the method of the invention as
applied to the editing process illustrated with reference to FIG. 2.
DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS
Three video cassette recorders 1, 2 and 3 are shown combined in an
equipment cluster 4 in the drawing. Each of the video cassette recorders
1, 2 and 3 consists of a tape handling unit 1', 2', 3' and a video-audio
processor and diagnostic test unit 1", 2", 3" related thereto hereinafter
referred to simply as a "processor". The three digital video cassette
recorders are connected with each other over a serial digital signal bus
system 5. In the illustrated example a coaxial cable connects the
individual handling units and processor units of the digital video
cassette recorders 1, 2 and 3. Within the tape handling units 1', 2', 3'
and the processor units 1", 2", 3" there are a number of coupling elements
6, 7, 8, 9 and 10 for connection with the bus 5. For example in the case
of the video cassette recorder 1 the coupling elements 6' to 9' are
inserted into the coaxial cable of the bus system 5 within the tape
handling unit 1' and the coupling element 10' likewise within the
processor unit 1" . In the digital video cassette recorders 2, and 3
correspondingly, the coupling elements 6" to 10" and 6"' to 10"' are
inserted in the coaxial cable. The coupling elements 6-10 serve for
connecting with computer controlled sending and receiving units further
mentioned below.
In copending U.S. patent application Ser. No. 07/186,168, filed Apr. 26,
1988 now U.S. Pat. No. 4,902,989, the construction and manner of operation
of such coupling elements is described. Such a coupling element
esstentially operates as a tapped pass-through filter.
Sending and receiving units 11', 12', 13' and 14' which serve for sending
and data telegrams are connected respectively to the coupling units 6',
7', 9' and 10'. Coupling unit 8' indicates that an additional sending and
receiving unit might well be used in a video recording unit. As used in
the system of copending application No. 07/191,011, the format of the data
telegrams can for example correspond to the IEEE-802.3 Standard, whereby
the following is prescribed: 8 bytes for a preamble, 6 bytes each for
destination and source addresses, 2 bytes for the length, 46-1518 bytes
for the actual data information and 4 bytes for a cyclic protective
redundance block. The transmision rate of the data telegrams can for
example be 10 Mbytes per second. Further details regarding such
transmissions are given in copending application Ser. No. 07/191,011,
filed May 6, 1988. In that patent application a system for transmission of
data and information within an equipment is described. Advantageously it
is possible to use in this system the economical integrated circuits chips
which are made for the Ethernets and the Cheapernets, which are
protocol-compatible with each other. Thus for example one of these
standard local networks (LAN) controls as sending and receiving unit 11',
a so-called "gateway"; as unit 12', a central control unit; as unit 13', a
time code generator, and as unit 14' a video and audio processor. In
contrast to the intra-equipment control concept of the above-mentioned
co-pending application Ser. No. 07/191,011, the method of the present
invention combines several major apparatus units systematically into a
control group (cluster) so that all functions of the individual apparatus
units are accessible as further described below. Within that group it is
not necessary for the addresses and the telegrams to conform with the
IEEE-802.3 standard.
The coaxial cable of the bus system 5 is also connected to an adaptor unit
15 provided for connection to the central operation desk 16. This adaptor
15 contains, in addition to a coupling element 20 serving the operation
desk 16, also an input 21 for supplying operating voltage for the
operation control desk. Terminating resistor networks 31 and 32 are
provided at the ends of the bus system 5.
Individual participating major units of the control group according to the
invention can also be allocated to the control unit 16 by dynamic address
change. With this feature of the invention the single control unit 16 can
be allocated to an equipment cluster 4 combining a considerable number of
apparatus units.
The control unit 16 can be equipped to control editing operations using two
professional video cassette recorder machines, for example. This is
illustrated in FIGS. 2 and 3. FIG. 2 shows only the two recorder machines
used in the example, in order to simplify the drawing, and the audio-video
processor (and test) units of the recorders shown in FIG. 1 are not shown
in FIG. 2 to simplify the drawing. On the other hand, FIG. 2 shows the
video connections between the recorders and with a monitor at the control
desk, which are details that were omitted in FIG. 1 to simplify the
drawing. The monitor could be built into the control unit 16, but in FIG.
2 it is shown as a separate unit at the control desk.
In FIG. 2 the keyboard 116 corresponds to the control unit 16 of FIG. 1 and
is coupled with the rest of the system shown by the serial data bus 105,
which corresponds to the bus 5 of FIG. 1, through the coupler 120, which
corresponds to the coupler 20 of FIG. 1, within the adapter 115, which
corresponds to the adapter 15 of FIG. 1. The bus 105 can be referred in
the present context to as an internal machine communication system (IMCS)
bus.
The bus 105 is coupled with the professional type video cassette recorder
101, hereinafter also referred to as machine #1, by the couplers 106, 107
and 109, corresponding to the couplers 6, 7 and 9 of FIG. 1 which are
respectively connected to the gateway unit 111, the central processing
unit (CPU) 112 and the time-code generator (TG) 113. The other connections
of the video cassette recorder 101 to the bus 105 which correspond to
other couplers shown in FIG. 1 are not shown in FIG. 2, in order to
simplify the drawing.
The second professional type video cassette recorder 201, hereinafter
sometimes referred to as machine #2, similarly has units 211, 212 and 213
shown coupled to the bus 105 respectively through couplers 206, 207 and
209.
At the location of the keyboard 116, which is usually a control desk, in
addition to the data display referred to in connection with the control
unit 16 of FIG. 1, a video monitor 130 is provided which is controlled
over the bus 105 through a coupler 140. The bus 105 has a terminating
network 131, 132 at each end, in each case symbolized by a resistance
connected to ground.
As shown in FIG. 2 the video cassette recorders 101 and 201 respectively
have video inputs 150 and 250 and likewise video outputs 155 and 255. If
more than two machines are present in the cluster, as for example in the
case of FIG. 1, it would be necessary for each machine to have a plurality
of video inputs, in order to make the respective video outputs of other
video cassette recorders available for selection, as the active input, by
each machine under control of the bus 105. The video outputs 155 and 255
are connected not only with the video inputs 250 and 150, respectively,
but they are also respectively connected to the video inputs 135 and 136
of the video monitor 130. There again, if there were more video cassette
recorders in the cluster, additional video inputs would be made available
at the monitor.
The recorders 101 and 201 of the cluster may be physically coupled to other
equipment through their respective gateway units 111 and 211, but such
other equipment outside the cluster cannot be controlled by the keyboard
116 with the convenience and versatility with which the equipment within
the cluster is controlled over the bus 105. The destination addresses for
the equipment outside of the cluster (coupled through the gateway units in
the cluster are not defined in the way that the addresses of the
equipments in the cluster) are defined.
FIG. 2 has some dotted lines interconnecting the keyboard 116 with the
video cassette recorder 101 and 201, three of them at the left going
between the keyboard 116 and the recorder 101 and the three at the right
going between the keyboard 116 and the recorder 201. These dotted lines do
not represent additional connections but they represent interactions of
the keyboard and either the recorder 101 or the recorder 201 which are
described in FIG. 3, where recorder 101 is referred to as machine #1 and
recorder 201 is referred to as machine #2.
FIG. 3 shows how an editing operation can be performed in accordance with
the invention by so-called dynamic addressing by which the keyboard 116
can function as the keyboard exclusively for machine #1 and as the
keyboard exclusively for machine #2, in alternation.
It is assumed for the purpose of FIG. 3 that it is desired to have recorded
video information reproduced by machine #1 and that when a certain part of
the record being played back is reached, to record the information on tape
which is available for recording machine #2. It is also assumed that the
machines #1 and #2 respectively have addresses 1 and 2, the monitor 130
the address 3, various unshown equipments have addresses 4, 5, 6 and 7 and
that addresses 8, 9, 10 . . . can be used for the keyboard 16. These
addresses can be assumed to be 4-bit codes.
As shown in FIG. 3, the first step is to assign the keyboard to machine #1,
which is done by setting a return address, by which only machine #1 can
reach it for initiating or maintaining interaction, for example the
address 8. Each message frame contains a destination address and a source
addresses. When machine #1 is addressed by the destination address
specified in an initial message to machine #1, the "source address "0 that
is transmitted to machine #1 will then be the address 8, which will be
recognized by machine #1 as the keyboard 16, which thereafter operates as
the keyboard control serving exclusively for machine #1. This address 8 is
so recognized only by machine #1.
The next step, shown at 402 in FIG. 3 is to start machine #1 in playback.
This is identified as command [1] in FIG. 2. Then the next step 403 is to
monitor the position of the record, command [2], which results in time
code data from the unit 113 of machine #1 being displayed on the data
display of the keyboard 116 and perhaps also in video output from line 301
being displayed on the video monitor 130 (which would involve a command to
the monitor not shown in FIG. 2). The next step 404 is a decision relating
to the tape position data in machine #1.
The edit points may have been previously determined in terms of time code
or by information which was added to the record in a previous running
through of the record being played back. The video monitor is mainly for
showing the operation that a signal is really being recorded: it is too
crude to determine the edit point exactly. So long as the edit point is
not reached, the return signal from stage 404 ("no") continues the
monitoring action specified by stage 403. As soon as the desired position
is reached the operation proceeds to stage 405 in which the keyboard is
assigned to machine #2 with setting of the appropriate address, now
address 9 for access by machine #2 to the keyboard unit 116 and its data
display. As in stage 401, that is done simply by the initial message from
the keyboard to the selected machine. This address 9 recognized only by
machine #2 as the new address of the keyboard 16. Thus any transmissions
from machine #1, which is still running, will not be able to reach the
keyboard.
Stage 406, starting of machine #2 in recording operation (command [3] in
FIG. 2) then takes place immediately. That is followed by a second
monitoring stage 407 and a second decision stage 408. The second decision
stage depends on information from machine #2, for example time codes from
unit 213. When the position for the end of this recording is reached, the
keyboard is still assigned to machine #2 and it accordingly then stops
machine #2 in stage 409 (command [5] in FIG. 2), followed by stage 410 in
which the keyboard is reassigned for machine #1 with setting of
appropriate return address (again 8), as before in stage 410. Then machine
#1 is stopped in state 411, which completes the operation shown in FIG. 3.
It will be noted from FIG. 3 that while the keyboard operates as a part of
machine #2, machine #1 continues to operate in playback as was commanded
while the keyboard was a member of machine #1.
There are several ways of providing the changes of address for response of
equipment to the keyboard and display unit 116. The simpler system would
be to have a separate response address for each of the equipments in the
cluster. Thus addresses 0 through 7 would be provided for addressing the
equipments and addresses 8 through 15 for responses directed to the
keyboard by the respective equipments. On the other hand, since the
various equipments in the cluster subject to control by the keyboard would
rarely all be controlled in a single operation in which one or the other
would be controlled in some kind of a sequence, the number of addresses
for responding to the keyboard could well be only half as many as the
number of equipment addresses. In this case when all the equipments are
stopped or otherwise finally disconnected from an operation conducted by
the keyboard, the stored return addresses should be erased so as to
prevent interference with future operations using the same set of return
addresses for a different set of equipments which might contain some
equipments of a previously used set.
By the above-identified system of assigning return addresses, the keyboard
and data display unit 116 can be made inaccessible for interaction in
either direction by all but one other equipment in the cluster.
All of the addresses usable by the control unit as a return address should
have a common feature by which they can be recognized as referring to the
control unit. In the illustrated case the feature was that they were
greater than 7 in an appropriate binary code. It could be that a certain
bit place is 1 or 0. It could be an artificial feature: for example the
feature that a circuit in the equipment in the control unit designed to
respond to any of the predetermined digital addresses will produce a
certain prescribed response.
Furthermore, if all the equipments are made unable to direct messages to
any of the addresses assigned to equipments other than the control unit,
the common feature of addresses assigned by the control unit as one of its
return addresses will be that the address in question is the source
address of a message received by an equipment other than the control unit.
It may be desired to prevent the keyboard from effectively sending a
message to machine #1 while it is still controlling machine #2. In the
system as so far described, any message to machine #1 that requires a
response to the keyboard will fail. A further provision could block even
transmission of a message to machine #1 in such a case. Such further
provision would limit the destination addressing, during the assignment of
a particular return address, to the destination address of the equipment
to which the return address confided. In such a case it may be necessary
to incorporate the video monitor in the control unit 16.
The addition of equipment, or its removal or substitution can be provided
for the cluster quite readily in accordance with the invention. This can
be done by making it possible for the keyboard to assign equipment
addresses to the various equipments at some initial stage of a series of
operations. That may require some kind of check system by which the
keyboard operator can verify which equipments have which addresses at any
particular time.
The above-described system of a variable return address for a control unit,
or its extension to variable addresses for equipment units of a cluster,
involves a situation which is normally intolerable within an electronic
data processing system. In conventional data processing systems it cannot
be accepted that the keyboard and display unit at a control desk could by
a change of address prevent mutual access between it and all but one (or
all but a few) of many equipments of a working group each having a central
processing unit (CPU).
For the purposes of the invention it is essential that when the keyboard
assigns itself to a particular equipment such as a video tape recorder, it
then becomes inaccessible for purposes of interaction from all other
equipments in the cluster. It will still be possible, without departing
from the invention, to provide communication of an unexpected malfunction
from an equipment that is participating in the operation but not at the
moment under control of the keyboard if such a malfunction threatens the
integrity of the operation as a whole. For example, while machine #1 is
playing back and the keyboard is controlling machine #2 in which the
output of machine #1 is being recorded, something goes wrong with machine
#1 so that it cannto perform its part of the operation at that time, a
message might be addressed to an interrupt address or to an alarm address
that would produce a visible signal in the neighborhood of the keyboard.
Although the invention has been described with reference to a particular
illustrative method, it will be understood that variations and
modifications are possible within the inventive concept.
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