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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to method and apparatus for recording and
reproducing information on and from a recording medium, such as a video
disc or a digital audio disc.
2. Description of Background Information
A recording system has been proposed in Japanese Patent Application No.
P63-46603, in which graphics codes, including picture information and
instruction codes indicating a mixing ratio at each point in a
two-dimensional picture formed by a video format signal are recorded as
being inserted as a subcode of a coded information signal, and at the time
of playback a signal according to the graphics code is mixed to the video
format signal at each point of the video format signal according to the
instruction codes.
With the system of the above-mentioned prior application, captions in a
plurality of different languages can be previously recorded in a manner
that each of the captions is recorded respectively in each of channels of
the subcode, and a superimposed caption in a designated language can be
selectively displayed at the time of playback.
Although the use of the superimposed caption an effective measure for
dealing with a multilingual program source, there has been a problem that
the time for viewing the major part (other than the caption) of the
picture is shortened by the necessity of viewing the superimposed caption.
Therefore, in the case of the recording and reproducing system of the
prior application, there has been a drawback that a program's appeal to
the viewer will be dwindled by the necessity of viewing the superimposed
caption.
OBJECT AND SUMMARY OF THE INVENTION
An object of the present invention is, therefore, to provide a method and
apparatus of recording and reproducing information, in which a plurality
of audio signals corresponding to speech in a plurality of languages can
be recorded on a recording medium, and an audio signal corresponding to
the speech in a desired language can be obtained from among the plurality
of audio signals recorded on the recording medium.
In the recording and reproducing method of the present invention, a
sampling operation at a predetermined frequency is respectively performed
against N (N is an integer equal to or greater than 3) channels or M (M is
an integer equal to or greater than 2) channel audio signals, a modulation
operation of a predetermined modulation system is performed respectively
for each of N or M channels of the sampled data, an identification code
identifying each channel is added to each of N or M channel coded
information signals, and subsequently the coded information signals are
multiplexed by a time division multiplexing operation and recorded on a
recording medium together with a channel of analog audio signal or by
themselves. At the time of play-back, at least two of the N channel coded
information signals designated by a command or at least two of the M
channel coded information signals and the one channel analog audio signal
designated by the command are selected and decoded arbitrarily using the
identification code, and a reproduction signal is generated by mixing the
at least two channels of audio signal.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram showing a recording apparatus according to the
present invention;
FIG. 2 is a diagram showing the structure of data blocks in the CD-I;
FIG. 3 is a diagram explaining the audio signals in the CD-I;
FIG. 4 is a block diagram showing an apparatus for playing a disc on which
information is recorded by the apparatus shown in FIG. 1; and
FIG. 5 is a flowchart showing the operation of the processor in the
apparatus shown in FIG. 4.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The embodiment of the present invention will be specifically described with
reference to the accompanying drawings.
In FIG. 1, audio signals of five channels and a video format signal which
are output from a video tape recorder, for example, are respectively
supplied to input terminals IN.sub.1 through IN.sub.5 and IN.sub.6. The
video format signal is supplied to an FM modulator 1 in which a carrier
signal of 8 MHz, for example, is modulated by the video format signal. An
FM signal output from this FM modulator 1 is in turn supplied to a
multiplexing circuit 2. On the other hand, the audio signal of a channel
CH1 is supplied to an FM modulator 3 in which a carrier signal of 2.3 MHz,
for example, is modulated in frequency by the audio signal of the channel
CH1. An FM signal output from this FM modulator 3 is supplied to the
multiplexing circuit 2.
The audio signals of channels CH2 through CH5 supplied through the input
terminals IN.sub.2 through IN.sub.5 are supplied to an analog-to-digital
converting circuits (referred to as A/D converters hereinafter) 5 through
8. The A/D converters 5 through 8 are configured respectively to sample
the audio signal of each channel at a sampling frequency of 37.8 KHz,
generate a digital data corresponding to the obtained sampled value, and
to output the generated digital data. The output data of the A/D
converters 5 through 8 are supplied to an ADPCM encoder 10. The ADPCM
encoder 10 is, for example, configured to compress the data into blocks on
the basis of the standard of discs designated CD-I, and to multiplex the
data with an output data of a control data generating circuit 11.
In the case of CD-I, the first 12 bytes of each block comprise a sync
signal called sync, and the 4 bytes following the sync comprise the data
group and are called the header. Of the 4 bytes of the header, 3 bytes
include address information as in the case of the subcode. That is, the 3
bytes form BCD codes indicating time in minutes, seconds and frames. Eight
bytes after the header comprise a data group, called the subheader. The
subheader contains attribute data required for processing blocks each
having only audio, video, or control data, by a time division multiplexing
using each block as a unit, and for executing a real-time processing for
that purpose. Such attribute data is written twice in the subheader. Each
of 4 bytes of the subheader is called file number, channel number,
submode, and data type.
The file number is a flag to be used, when blocks belonging to the same
file are interleaved, for identifying such a state.
The channel number is a flag for discriminating blocks which may be
selectively used in the same file, and as many as 32 channels can be
defined. For instance, this flag may be used in case two channels in
English and in Japanese are prepared in the same file and either one of
the channels is to be selected by the user.
In the submode, a flag indicating the attribute of the block is contained.
For example, a flag to be used for the discrimination between form 1 and
form 2, or a flag indicating whether the block carries an audio data
(audio block) or a control data (control block) is contained in the
submode.
The data type has different definitions depending on the type of block,
i.e., the audio block, video block, or data block. For example, in the
case of the audio block, a flag indicating the type of coding of the audio
signal is contained in the data type.
In the case of the data structure of the CD-I, there are two forms i.e.,
form 1 and form 2, which can be identified by the flag in the subheader.
The ADPCM encoder 10 in the recording system is configured to form a data
block of the form 2 which is illustrated in FIG. 2. In the case of the
form 2, a user data of 2324 bytes and a reserve data of 4 bytes are
arranged after the subheader.
On the other hand, four types of audio data shown in FIG. 3 are prepared as
the audio data of the CD-I. Of these four types, three types are ADPCM
data which are named level A, level B, and level C, respectively. The
ADPCM encoder 10 is configured to form a level B data, that is, an ADPCM
data having four bits of the transmission bits, whose bandwidth and
compression rate are 17 kHz and 1/4 respectively.
The control data generation circuit 11 is configured to store control data
representing commands to the disc player such as the search command, pause
command, which are previously input by the key operation for example, to
compose blocks having the stored control data as its user data as
illustrated in FIG. 2, and to output the blocks in response to command
signals.
The output signal of the ADPCM encoder 10 is supplied to a CD system
encoder 13 through an error detection and correction code adding circuit
12. The CD system encoder 13 also receives output signals of a control
signal generating circuit 14 and an error-detection/correction code adding
circuit 15. The control signal generating circuit 14 is configured to
generate such data as a data indicating the elapsed time after the start
of the application of the audio signals to input terminals IN.sub.1
through IN.sub.5 and a data indicating the pause between program areas and
the program area of the audio signal.
Output data of a graphics code generating device 16 is supplied to the
error detection and correction code adding circuit 15. The graphics code
generating circuit 16 is configured to store a graphics code corresponding
to a picture processing instruction which has been input by a key
operation for example, and to read out the stored graphics code in
response to a command, and to output it. The error detection and
correction code adding circuit 15, on the other hand, is configured to
perform interleaving of the output data of the graphics code generating
circuit 16 and adding of correction codes.
The CD system encoder 13 is configured to use the output signal of the
control signal generating circuit 14 as the data of the Q and P channels
of the subcode on the basis of the CD system, to use the output signal of
the graphics code generating circuit 16 as the data of the R through W
channels of the subcode, and to form a recording signal by inserting the
subcode data into the digital data from the ADPCM encoder 10. The output
signal of the CD system encoder 13 is supplied to a modulator 18 in which
the input signal is converted to an EFM (Eight to Fourteen Modulation)
modulation signal. The output signal of the modulator 18 is supplied to
the multiplexing circuit 2 where it is multiplied in frequency with the
FM-modulated video format signal and the audio signal of the channel CH1.
The output signal of the multiplexing circuit 2 is supplied to a light
modulator (not shown) of the optical disc player, so that the intensity of
the light beam irradiated on the recording surface of the disc is
modulated. The disc is rotated so that the linear velocity is kept
constant. As a result, the graphics code including picture information is
recorded as the subcode on the recording disc, in addition to the FM
modulated video format signal, the audio signal of the channel CH1, and
the digital audio signal which comprises the ADPCM data signal as the
coded information signal.
The graphics code generating device 16 is configured to generate various
codes corresponding to the picture processing instructions based on the
picture information recording and reproducing system utilizing the
subcode, which is described in Japanese Patent Application Laid Open No.
P63-46603.
FIG. 4 shows a disc player for playing a disc on which information has been
recorded by the above-described recording system. As shown, the disc 20 is
driven by a spindle motor 21. As the disc 20 rotates, the signal recorded
on the disc is read by means of a pickup 22. The pickup 22 is carried on a
carriage (not shown) which is driven by a carriage motor 23 and movable in
a radial direction of the disc 20. With this arrangement, the position of
an information reading point (information reading light spot) of the
pickup 22 is arbitrarily determined in the radial direction of the disc
20. Furthermore, the player is provided with various servo systems such as
the spindle servo system, focus servo system, tracking servo system, and
carriage servo system. Since these servo systems themselves are well
known, the explanation thereof is not given in the specification.
The spindle motor 21 and the carriage motor 23 are respectively driven by
the spindle servo system and the carriage servo system, or driven by a
playing part control circuit 24. In response to commands from the system
controller 25, the playing part control circuit 24 performs various
operations such as the drive of the spindle motor 21 and the carriage
motor 23, and the on-off control of the servo systems mentioned above, and
the jump control.
The RF (radio frequency) signal output from the pickup 22 is amplified by
an RF amplifier 27 and supplied to FM demodulation circuits 34 and 35 and
to an EFM demodulation circuit 36 through band-pass-filters (BPFs) 31, 32,
and 33 respectively. The frequency characteristics of the BPFs 31, 32, and
33 are chosen to permit only the video format signal component, the audio
signal component of the channel CH1, and the digital audio signal
component respectively.
The EFM demodulation circuit 36 is configured to perform an EFM
demodulation operation of a pulse signal obtained by slicing the digital
audio signal separated from the RF signal by means of the BPF 33, and to
obtain the digital data and subcode including audio information and
control information. The digital data including the audio information and
the control information output from the EFM demodulation circuit 36 is
supplied to the de-interleaving and interpolating circuit 37. The
interleaving and interpolating circuit 37 is configured to perform the
following operations. In cooperation with RAM 38, the de-interleaving and
interpolating circuit 37 puts the digital data in its original order,
whose order has been changed by the interleaving operation at the time of
recording. The de-interleaving and interpolating circuit 37 then transmits
the digital data to an error correction circuit 39, and performs the
interpolation of erroneous data in the output data of the error correction
circuit 39 by using the average value interpolation method for example,
when a signal indicating the impossibility of the correction is issued
from the error correction circuit 39. The error correction circuit 39 is
configured to perform an error correction operation using the CIRC (Cross
Interleave Reed Solomon Code) and to supply the digital data to
de-interleaving and interpolating circuit 37, and to generate the signal
indicating the impossibility of the correction if the correction of error
is not possible.
From the de-interleaving and interpolating circuit 37, data having a block
structure as shown in FIG. 2 is output, and supplied to an ADPCM decoder
40. Furthermore, a data from the system controller 25 indicating the
channel designated by a manual operation is supplied to the ADPCM decoder
40. The ADPCM decoder 40 is configured to perform the following
operations. At first, the ADPCM decoder 40 compares the channel number in
the subheader of the data block output from the de-interleaving and
interpolating circuit 37 with the output data of the system controller 25,
and decodes only the ADPCM data of blocks of the designated channel. On
the other hand, the ADPCM decoder 40 senses blocks in which the control
data is user data, by using the submode in the subhead of the data blocks
output from the de-interleaving and interpolating circuit 37, and extracts
the control data and transmits it to the system controller 25
subsequently.
The ADPCM data demodulated by the ADPCM decoder 40 is supplied to a D/A
(digital-to-analog) converting circuit 41, so that it is converted to an
analog audio signal. The audio signal output from the D/A converting
circuit 41 is supplied to a mixing circuit 42 which comprises an adder for
example, where it is mixed with the audio signal of the channel CH1
demodulated by the FM demodulation circuit 35.
On the other hand, the subcode output from the EFM demodulation circuit 36
is supplied to a subcode error correction circuit 45 where it is treated
by the error correction operation. The P and Q-channel bits of the subcode
are supplied to the system controller 25. The R through W channels of the
subcode to which the error correction process has been performed by the
subcode error correction circuit 45 are supplied to a graphics decoder 46.
The graphics decoder 46 includes, for example, 16 memories respectively
corresponding to channels which are formed by the R through W channels of
the subcode and designated by the channel number bits in the graphics
codes including picture information. The graphics decoder 46 is configured
to write data into these memories according to the graphics codes, to form
a video format signal by successively reading out data stored in a memory
corresponding to a channel designated by the output data of the system
controller 25, and to output the video format signal. The graphics decoder
46 also forms data indicating the mixing ratio in a mixing circuit 47, and
output the data subsequently. The mixing circuit 47 comprises a video
switch for example, and is configured to mix the video format signal
output from the graphics decoder 46 and the video format signal output
from the FM demodulation circuit 34 at a mixing ratio according to the
output data of the graphics decoder 46. The output signal of the mixing
circuit 47 is supplied to a video output terminal. By the operation of the
graphics decoder 46 and the mixing circuit 47, an image produced from the
subcode is inserted into the video image produced by the video format
signal recorded by the FM modulation, so that the superimposition of a
caption, for example, is enabled. In addition, the details of the graphics
decoder 46 and the mixing circuit 47 are given in the aforementioned
Japanese Patent Application Laid Open No. P63-46603.
The system controller 25 is constituted by a microcomputer including a
processor, ROM, RAM, and a timer, for example. In response to various
commands corresponding to key operations supplied from the operation part
48, the system controller 25 executes arithmetical operations on the basis
of data or programs stored in the ROM, RAM or the like, and subsequently
supplies instruction signals for the play, search, jump operation or the
like, to the playing part control circuit 24.
The operation of the processor of the system, controller 25 in the
apparatus having the construction mentioned above, will be explained with
reference to the flowchart of FIG. 5.
When the operational mode of the player is set to the play mode by the
execution of the main routine, a play mode control routine or the like,
the processor proceeds to step S1 by an interruption of the timer for
example, to detect whether the designation of channel has been made. If it
is detected in step S1 that any one of the channels has been designated,
the processor then supplies data indicating the designated channel to the
ADPCM decoder 40 and to the graphics decoder 46 (step S2). If, on the
other hand, it is detected in step S1 that no channel has not been
designated, the processor then supplies a predetermined data, for example
a data indicating the channel CH2, to the ADPCM decoder 40 and the
graphics decoder 46 (step S3).
After the execution of the operation of step S2 or step S3, the processor
judges as to whether or not the control data is being output from the
ADPCM decoder 40 (step S4). If it is detected in step S4 that the control
data is being output, then the processor transmits a command indicated by
the control data to the playing part control circuit 24 (step S5), and
restarts the execution of the routine whose procedure was taking place
immediately before proceeding to step S1. Furthermore, if it is detected
in step S4 that the control data is not being output, the processor also
restarts the execution of the routine whose procedure was taking place
immediately before proceeding to step S1.
By the steps S1 through S3 in the operation described above, the data
indicating the designated channel (when a channel has been designated) or
the data indicating the predetermined channel (when no channel has been
designated) is supplied to the ADPCM decoder. As a consequence, the coded
information signal of the channel indicated by the output data of the
system controller 25 is selectively decoded in the ADPCM decoder 40, and a
digital data is obtained by sampling the audio signal of the channel
indicated by the output data of the system controller 25 at a sampling
frequency of 37.8 KHz. This output signal of the ADPCM decoder 40 is
converted to an analog signal by a D/A converting circuit 41, and in turn
mixed with the audio signal of the channel CH1 output from the FM
demodulator circuit 35 at the mixing circuit 42.
With this feature, multilingual discs designed for countries where the NTSC
system is adopted can be produced. For example, audio signals are recorded
such that an audio signal corresponding to the sound effect (SE) is
recorded as the audio signal in the channel CH1, an audio signal
corresponding to the speech in Japanese is recorded as the audio signal in
the channel CH2, an audio signal corresponding to the speed in English is
recorded as the audio signal in the channel CH3, an audio signal
corresponding to the speech in Chinese is recorded as the audio signal in
the channel CH4, and an audio signal corresponding to the speech in Korean
is recorded as the audio signal in the channel CH5.
Furthermore, by recording the image of captions in each language as the
picture information recorded in the form of the subcode, it becomes
possible to obtain the speech in each language also in the form of
superimposed captions at the same time as the generation of the speech
sound. Therefore, this system can be utilized for learning foreign
languages.
In addition, it is conceivable to arrange the system such that the
selection of the caption by the subcode is performed at the same time as
the section of the speech sound by the ADPCM, so that the Japanese
caption, for example, is displayed at the same time as the Japanese speech
sound is selected.
Also, by the operation of steps S4 and S5, particular reading operations in
each channel are controlled according to control data recorded in each
channel. Therefore, besides the advantage that sounds having different
contents can be generated from a single disc depending on the selection of
channel, different reading operations, i.e., different combinations of the
search, pause, or other operations can be attained by a single disc
playing apparatus.
So far, the explanation of the present invention has been made with respect
to discs of the NTSC system on which an audio signal is recorded in the
form of analog signal, by way of example. On the other hand, in the case
of discs of the PAL system on which no audio signal is recorded in the
form of analog signal, four channels of audio signals can be recorded and
reproduced by using the level B of the ADPCM data. In this case, the audio
signal corresponding to the sound effect is used as the audio signal of
the channel CH1, an audio signal corresponding to speeches in French is
used as the audio signal of the channel CH2, an audio signal corresponding
to speeches in German is used as the audio signal of the channel CH3, and
an audio signal corresponding to speeches in English is used as the audio
signal of the channel CH4, and the audio signals of the channels CH1
through CH4 are digitized and recorded as the ADPCM data. By arranging the
ADPCM decoder 40 to decode ADPCM data of the channel CH1 and the
designated channel, the same feature as with the discs of the NTSC system
can be obtained.
Additionally, in the case of music software, a recording can be performed
in such a manner that the so called minus 1 (or minus 2, minus 3 . . . )
is recorded in the channel CH1, and the part excluded from the minus 1 is
recorded in the channel CH2, and other excluded part is recorded in the
channel CH3. With this type of recording, various parts selected
arbitrarily can be mixed together at the time of play-back.
As explained in the foregoing, in the recording and reproducing method
according to the present invention, a sampling operation at a
predetermined frequency is respectively performed against N (N is an
integer equal to or greater than 3) channels or M (M is an integer equal
to or greater than 2) channel audio signals, a modulation operation of a
predetermined modulation system is performed respectively for each of N or
M channels of the sampled data, an identification code identifying each
channel is added to each of N or M channel coded information signals, and
subsequently the coded information signals are multiplexed by a time
division multiplexing operation and recorded on a recording medium
together with a channel of analog audio signal or by themselves. At the
time of play-back, at least two of the N channel coded information signals
designated by a command or at least two of the M channel coded information
signals and the one channel analog audio signal designated by the command
are selected and decoded arbitrarily using the identification code, and a
reproduction signal is generated by mixing the at least two channels of
audio signal.
Therefore with the method according to the present invention, a single disc
can be used for recording multilingual sounds, and reproduced information
will become much easier to understand as compared with the case where only
the superimposed caption is provided. Furthermore, with respect to the
production of discs, it will become only necessary to prepare one disc.
Thus, the control of production process will also become much easier. In
that case, a plurality of sound sources in different languages must be
prepared. However, there are more advantages than shortages in an overall
viewpoint. Especially, the use of the method according to the present
invention is advantageous in Europe where a plurality of languages are
used in the same continent, or multilingual countries such as the Soviet
Union and China. In addition, the method can be effectively applied for
the preparation of musical software.
Moreover, other various applications of the method according to the present
invention are also conceivable since a plurality of audio channels are
available. For instance, a channel for an explanation of the recorded
software can be provided. Since the explanation is presented in the voice,
it is more effective than conventional liner notes. Assume that a
narration by a famous commentator is inserted into a movie program. In
that case, it is possible to compose the program such that an indication
of a program area to be searched is given in the narration of the
commentator, and an explanation given by the commentator is automatically
provided together with the pictures of the searched area when the
designated program area is searched in accordance with the operation by
the user. Moreover, in this case, the system can be arranged such that the
searching operation is automatically performed by using the control codes.
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