Data recording system with midi signal channels and reproduction apparatus therefore

A magnetic disc 13 serving as a memory medium has stored therein sound control MIDI messages and MIDI messages containing character codes so as to make it possible to reproduce performance data and image data over a prolonged period of time although the memory medium has a given capacity. A MIDI sequencer 14 delivers the MIDI messages serially based on the signals read from the disc 13. A sound source device 15 performs specified music by being controlled by the sound source control MIDI messages. An image forming device 20 displays a text on a display 21 based on the MIDI messages containing the character codes.

FIELD OF THE INVENTION 
The present invention relates to memory media having stored therein signals 
(MIDI signals) according to MIDI (Musical Instrument Digital Interface) 
standard which is adopted worldwide generally for the communication 
control of sound source devices for keyboards or like musical instruments 
and also to a reproduction apparatus for the memory media. More 
particularly, the invention relates to memory media having stored therein 
image data for showing the images of characters or the like on a display 
in addition to the performance data to be fed to the sound source device, 
and a reproduction apparatus for simultaneously reading the performance 
data and the image data from the memory medium 
BACKGROUND OF THE INVENTION 
The method of data communication according to the MIDI standard is an 
asynchronous serial communication method as prescribed in "MIDI 1.0 
DETAILED SPECIFICATION DOCUMENT VERSION 4.0," and the data transfer rate 
used in this method is 31.25 kbit/sec. When one byte (8 bits) of data is 
to be transferred, one start bit and one stop bit are added thereto, and 
the data therefore comprises 10 bits in its entirety. 
In the data communication according to the MIDI standard, data is handled 
in the unit of "messages" comprising a plurality of bytes. With reference 
to FIG. 7, these messages are divided generally into channel messages and 
system messages, which are further classified into different types of 
messages, i.e., five types in total. The messages of these types include a 
channel voice message, channel mode message and system common message each 
comprising one status byte, and one or two data bytes led by the status. 
According to the MIDI standard, up to 16 channels are settable. The status 
byte includes channel number data indicating a particular channel to which 
the message is directed. Utilizing the concept of the MIDI channels, 
therefore, for example 16 musical instruments are individually 
controllable independently through a single MIDI cable. 
The channel voice message shown in FIG. 7 is further classified according 
to the function as shown in FIG. 8. The note on message included in the 
classified messages corresponds to "production of sound" which is the most 
essential of all items of performance data. As seen in FIG. 9 (a), this 
message is composed of the status byte "9Xh" (wherein h is a symbol 
indicating that hexadecimal notation is used, and X is a hexadecimal 
number representing a particular MIDI signal channel and is one of the 
values 0 to F), and two bytes of data subsequent to the status byte. The 
first data byte is termed "note number" for controlling the musical 
interval. The second data byte is called "velocity" for controlling the 
sound volume. 
On the other hand, the note off message corresponds to "cessation of sound" 
and is composed of the status byte "8Xh" and two bytes of data subsequent 
thereto as shown in FIG. 9(b). Incidentally, the note on message and the 
note off message are paired, and a pair of note on and note off messages 
are identical in note number. 
The sound source device to be controlled by MIDI signals starts to produce 
a sound with specified musical interval, sound volume and tone color in 
response to one message, and ceases producing the sound in response to 
another message thereafter given. In the simplest case, therefore, a 
specified sound can be continuously produced from the device only for a 
predetermined period of time by intermittently feeding to the device a 
message specifying particular musical interval, sound volume and tone 
color, a message for starting sound production and a message for ceasing 
the sound production, each at a predetermined time. 
In the case where the specified sound is to be produced only for the 
predetermined period of time with MIDI signals, sound signals need not be 
continuously given over the period of sound production unlike the sound 
reproduction by audio tape recorders or the like but MIDI signals need 
only to be fed to the sound source device intermittently, so that the 
specified sound can be produced with a greatly reduced amount of data. 
Incidentally, MIDI signals are usually stored in a medium in a format 
adapted for computer communication together with timing data for 
controlling the output timing of messages. 
In recent years, so-called "KARAOKE" apparatus have found wide household 
and business uses for enjoying singing songs to the accompaniment of music 
reproduced from disc recording media. 
Video disc players having a sound mixing function are conventionally 
utilized as such KARAOKE apparatus. The sound signal of an accompaniment 
reproduced from a video disc and the sound signal of a song input from a 
microphone are mixed together to release the resulting sound from a 
speaker. Further the images of the corresponding text reproduced from the 
video disc are projected one after another on the screen of a display in 
synchronism with the reproduction of sound signal of the accompaniment. 
Video discs for KARAOKE each have stored therein a plurality of musical 
compositions or tunes. Since the accompaniment sound signal and the text 
image signal for each tune are recorded at the same time as superposed, a 
very great amount of data is stored for each tune. For this reason, the 
number of tunes which can be stored in one disc is inevitably much smaller 
than in other discs, for example, a compact disc wherein the sound signal 
only is stored. 
Accordingly, the conventional KARAOKE apparatus have the drawback of 
necessitating frequent changes of discs upon request for tunes. 
SUMMARY OF THE INVENTION 
An object of the present invention is to provide a memory medium having 
stored therein performance data as to a large number of tunes and image 
data for displaying the corresponding texts so as to realize a KARAOKE 
apparatus which does not necessitate very frequent change of media upon 
request for tunes. 
Another object of the invention is to provide a memory medium having stored 
therein performance data and image data in the form of MIDI signals to 
thereby reduce the amount of data per tune. 
Another object of the invention is to provide a reproduction apparatus for 
use with a recording medium having stored therein performance data and 
image data in the form of MIDI signals, the apparatus being adapted to 
control a sound source device based on the performance data read from the 
medium for an automatic performance and at the same time, to show the 
images of a text or the like on a display based on the image data read 
from the medium. 
The present invention provides a memory medium having stored therein 
performance data as assigned to at least one of MIDI signal channels, and 
image data relating to the performance data and as assigned to at least 
one of the other channels according to MIDI standard. 
The memory medium embodying the invention has stored therein image data 
utilizing at least one of MIDI signal channels, so that the amount of data 
to be stored can be greatly reduced unlike the conventional video disc or 
the like wherein a video signal and an audio signal are recorded at the 
same time. 
The present invention further provides a reproduction apparatus which 
comprises signal reading means for reading MIDI signals from the memory 
medium and delivering the signals, a sound source device for receiving one 
of the read signals from a channel containing the performance data to 
produce an audio signal based on the performance data, sound release means 
for receiving the audio signal, an image forming device for receiving 
another one of the read signals from a channel containing the image data 
to produce a video signal based on the image data, and display means for 
receiving the video signal. 
With the reproduction apparatus embodying the invention, the performance 
data and the image data are retrieved from the memory medium in the form 
of MIDI signals, so that a MIDI sequencer serving as signal reading means 
for the conventional medium wherein performance data only is stored can be 
used as it is as the signal reading means. This simplifies the 
construction of the apparatus.

DETAILED DESCRIPTION OF EMBODIMENT 
The present invention will be described below with reference to an 
embodiment thereof which is a KARAOKE apparatus. 
Memory Medium 
First, the format of MIDI signals for use in the memory medium will be 
described. 
According to the present embodiment, character codes serving as image data 
are assigned to the data position of the note on message and the note off 
message shown in FIG. 8 utilizing one of 16 MIDI signal channels. 
Usable as character codes are, for example, JIS (Japanese Industrial 
Standard) codes which are widely used in Japan. In this case, "A" in the 
alphabet, for example, is represented by 23h as an upper byte and 41h as a 
lower byte. The JIS codes include not only characters but also flat, sharp 
and like symbols or devices. However, JIS is not limitative; also usable 
are standards empolyed in other countries or optionally determined 
standards. 
FIG. 2, (a) and (b), shows assignment of character codes to the note on 
message and note off message. According to the MIDI standard, MSB of data 
bytes of the note on message and note off message must invariably be set 
to 0 to indicate that the byte is a data byte, so that the amount of data 
which can be stored in one data byte is 7 bits. 
Accordingly, the note on message and the note off message are to be 
respectively assigned the upper byte and the lower byte of the character 
codes, each at the position of LSB of the data byte 1 and 7 bits of the 
data byte 2 as combined therewith, i.e., at the position of 8 bits, as 
illustrated, so as to represent one character with these two messages. 
Further assigned to the remaining 5 bits of the data byte 1 is an address 
which is used when items of character code data are successively written 
in memories (indicated at 3 and 4 in FIG. 4) for temporarily storing the 
character code data to be displayed on a screen at a time as will be 
described later. The positions of characters to be displayed on the screen 
are determined by such addresses. 
FIG. 3, (a) and (b), shows the JIS codes "23h" and "41h" representing "A" 
in the alphabet, as assigned to the data positions of the note on message 
and the note off message, respectively, along with the address "06h." 
FIG. 6 shows as an example the character display positions on the screen of 
a display. Characters of a text are assigned to the respective positions, 
numbered 1 to 20, at the lower portion of the screen. Accordingly, the 
characters 20 in total number are displayed on the screen at a time. 
To the same channel as the channel containing character codes of the memory 
medium or to a different channel thereof, control data other than the 
character codes, for example, data for controlling the memory, can be 
assigned. As such control data, codes not used as the character codes must 
be used. For example, 00h as an upper byte and 00h as a lower byte 
provide a memory reset command. 
The command is interpreted by the microcomputer to be described below 
(indicated at 2 in FIG. 4), whereupon the microcomputer feeds the reset 
command to the memory. The address to be used at this time is of an 
optional value. 
The character codes thus formulated into the MIDI signal format and the 
MIDI signal for controlling a sound source are stored in the memory medium 
in the form of computer signals permitting computer communication, along 
with a timing signal for determining when to deliver MIDI messages. 
Although magnetic discs, magnetic tapes and optical discs are generally 
useful as memory media, also usable are other media such as semiconductor 
memories. 
Reproduction Apparatus 
Next, the reproduction apparatus for the foregoing memory medium will be 
described. 
With the present embodiment, the memory medium is a magnetic disc 13 as 
shown in FIG. 1. The disc 13 has recorded in the format described MIDI 
signals including performance data and image data, along with the timing 
signal. 
The signals stored in the disc 13 are read by a MIDI sequencer 14, which in 
turn delivers the messages of the MIDI signals serially with the timing 
specified by the timing signal. 
The MIDI signals output from the MIDI sequencer 14 are sent to a sound 
source device 15 and an image forming device 20. A channel containing the 
performance data is registered in the sound source device 15 in advance, 
and a channel containing the image data in the image forming device 20. 
Accordingly, the sound source device 15 receives the signal containing the 
performance data from the channel concerned among the other MIDI signals 
sent forward from the MIDI sequencer 14, reads the message from the 
channel and produces an audio signal based on the read message. 
The audio signal is sent to a mixer 16 and mixed with a song audio signal 
delivered from a microphone 17. The mixed signal is fed via an amplifier 
18 to a pair of opposite speakers 19, 19, which release a sound. 
On the other hand, the image forming device 20 receives the signal 
containing character codes from the channel concerned among the other MIDI 
signals forwarded from the MIDI sequencer 14, reads the character codes 
and address assigned to the note on and note off messages of the channel, 
prepares a text-containing image signal based on the read data and feeds 
the signal to a display 21. Consequently, the text of the tune concerned 
is shown on the screen of the display in synchronism with the audio 
signal. 
FIG. 4 shows the circuit construction of the image forming device 20 in 
detail. 
The MIDI signals output from the MIDI sequencer are received by a MIDI 
signal receiving circuit 1 and thereafter sent to a microcomputer 2, in 
which the channel assigned the character codes is set in advance. From 
among the MIDI signals forwarded from the receiving circuit 1, the 
computer reads the note on and note off messages of the set channel. 
For setting a desired channel in the microcomputer 2, the desired channel 
number may be made settable using number entry keys or like input means. 
It is then possible to suitably change the setting even when the number of 
MIDI channels for controlling the sound source differs for different 
memory media and, accordingly, even if a different MIDI channel is to be 
used for character codes. 
The microcomputer 2 retrieves the upper byte and lower bytes of the 
character codes, address and memory control data from the read note on and 
note off messages, and feeds these items of data to first and second 
display data memories 3, 4 via the corresponding output ports. 
The first data memory 3 receives character code upper bytes and stores the 
upper bytes one after another, each at the address specified by the 
address data. Similarly, the second data memory 4 stores lower bytes one 
after another. 
As seen in FIG. 5, the addresses in the data memories 3, 4 are in 
corresponding relation with the respective display positions on the 
display screen. The storing address of the character code upper byte and 
lower byte determines the position where the corresponding character is to 
be displayed on the screen. 
When the data memories 3, 4 receive the memory control data for resetting 
the memories, the memories 3, 4 are reset after delivering the written 
data to a character generator 5. 
The character generator 5 shown in FIG. 4 has an internal memory, converts 
the character codes sent from the data memories 3, 4 to a character signal 
and feeds the character signal to a display control circuit 10 in response 
to a control signal given by a display timing output circuit 9. 
The display control circuit 10 controls a first switch 12 based on the 
character signal and an output timing signal from the display timing 
output circuit 9 to superimpose a character on the display screen at the 
specified position. 
More specifically, the first switch 12 has an input terminal a to which an 
output terminal of a second switch 11 is connected, and another input 
terminal b to which a white level generator 22 is connected for producing 
a predetermined image signal in accordance with the whiteness level of the 
screen. The second switch 11 has an input terminal a to which a terminal 6 
is connected for receiving an image signal from a video disc player or 
like external image device. The switch 11 has another input terminal b to 
which a black burst signal generating circuit 7 is connected for producing 
a monochromatic background picture of black or blue. The second switch 11 
is selectively closed at either one of the input terminals as desired by 
the user. 
When the screen portion other than the portion where characters are 
superimposed is used for display, the first switch 12 is closed at the 
terminal a, so that the external image signal from the terminal 6 or a 
black burst signal from the circuit 7 is fed to the display. While the 
superimposition area at the bottom of the screen is horizontally scanned, 
the first switch 12 is changed over from the terminal a to the terminal b 
for a length of time corresponding to the thickness of characters in 
response to the control signal from the display control circuit 10, 
whereby the characters are superposed at the white level on the screen. 
FIG. 6A shows how "A" of the alphabet is superimposed on the screen. Pulses 
P as illustrated are fed as the control signal to the first switch 12 to 
change over the switch to the terminal b to apply the white level image 
signal to the image signal on a horizontal scan line H. 
At this time, the display timing output circuit 9 shown in FIG. 4 
calculates the display position of each character on the screen from a 
horizontal synchronizing signal (H. SYNC) and a vertical synchronizing 
signal (V. SYNC) from a synchronizing signal separating circuit 8 to 
prepare an output timing signal and feeds the signal to the display 
control circuit 10. 
In this way, a text is shown on the display 21 of FIG. 1, as superimposed 
thereon and synchronized with the accompaniment. 
Although one embodiment of the present invention has been described above, 
the invention is not limited to this embodiment but can be modified 
variously. For example, the characters of given size are displayed in a 
fixed position according to the foregoing embodiment, whereas the position 
and the size are variable as desired by assigning the memory control data 
signals for controlling the display position and size of characters. 
Further if different items of character data are stored in different MIDI 
channels, desired character data can be reproduced by changing the channel 
during reproduction. For example, a first channel may be assigned a 
Japanese text, with a second channel assigned an English text. One of the 
Japanese and English texts can then be selected as required. 
The character codes assigned to the note on and note off messages on MIDI 
signal according to the foregoing embodiment may alternatively be assigned 
to other messages. For example, the character codes can be assigned to 
exclusive messages for which a an optional format can be determined as 
required. 
Further if the character generator described is replaced by a circuit for 
outputting graphic presentations corresponding to the code input, not only 
characters but graphic presentations can be displayed. 
According to the invention described above, performance data and image data 
can be stored in memory media with use of a greatly reduced amount of 
data. This gives an increased period of reproduction to memory media of a 
given capacity. The invention is therefore useful especially for KARAOKE 
apparatus. 
Moreover, the performance data and the image data can be readily retrieved 
from the memory media using a conventional MIDI sequence as it is without 
any modification. This serves to simplify the apparatus in construction.