Digital signal recording and reproducing apparatus and digital signal recording and reproducing method collectively recording inspecton codes and forming a gap therebetween during post-scoring

A digital signal recording and reproducing method and apparatus for digitally recording and reproducing first and second signals in tracks on a magnetic recording includes an encoder and a recording unit. The encoder separately error-correcting encodes the first and second signals of a first and second type, respectively, to produce at least first and second inspection codes corresponding to the first and second signals. The first and second inspection codes have first and second lengths, respectively. The recording unit records the first and second signals and the first and second inspection codes in tracks of the magnetic recording medium so that the first and second signals and the first and second inspection codes are recorded in a track without a gap therebetween.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a rotary head type digital signal recording and 
reproducing apparatus and to a digital signal recording and reproducing 
method for digitally recording the video and audio signals on a magnetic 
tape. 
2. Description of Related Art 
Conventionally, various systems of rotary head type digital signal 
recording and reproducing apparatus have been developed. As a typical 
example of such apparatuses, a digital VTR for broadcasting service known 
as D-2 system will be given an explanation hereinafter. 
FIG. 1 is a schematic block diagram showing one example of D-2 system 
digital VTR. In the figure, numeral 101 is an input terminal for video 
signal, via which an analog video signal enters an A/D converter 103, 
which converts the signal to a digital signal and outputs it to a digital 
recording signal processor 105. On the other hand, numeral 102 is an input 
terminal for audio signal, via which an analog audio signal enters an A/D 
converter 104, which converts the signal to a digital signal and outputs 
it to the digital recording signal processor 105. The digital recording 
signal processor 105 carries out error-correction encoding, digital 
modulation, etc. and outputs the processed signal to recording AMPs 106, 
107. The recording AMPs 106, 107 amplify input signals. The amplified 
signal is distributed to four recording and reproducing heads 112, 113, 
114, and 115 via recording/reproducing selecting switches 108, 109 and via 
head selection switches 110, 111 and is recorded on a magnetic tape (not 
shown). Numerals 116-122 show components of reproducing part, and 
reproducing AMPs 116 and 117 amplify signals which are reproduced on 
recording and reproducing heads 112, 113, 114, 115 and are transferred 
through switches 110, 111 and through switches 108, 109, and then, output 
the amplified signal to a digital reproducing signal processor 118. The 
digital reproducing signal processor 118 carries out digital demodulation 
and error-correction decoding etc., and outputs video and audio signals of 
normal signal strings to D/A converters 119 and 120. The D/A converter 119 
converts the input signal to the original analog video signal and outputs 
it via an output terminal 121. The D/A converter 120 converts the input 
signal to the original analog signal and outputs it via an output terminal 
122. 
FIG. 2 shows a tape format of D-2 system digital VTR. As shown in FIG. 2, 
in the D-2 system, a cue, time record, and control tracks are provided in 
the longitudinal direction of the magnetic tape. On the track tilted in 
the longitudinal direction of the magnetic tape, video and audio signals 
are digitally recorded. The audio signal is arranged in a total of four 
channels; the video signals is sandwitched by four channels with two 
channels on either side. 
Referring now to FIG. 1, operations will be described in detail 
hereinafter. A composite video signal supplied to the input terminal 101 
is sampled at quadruple subcarrier frequency (14.318 MHz) and is converted 
into the digital signal of 8 quantized bits (at the A/D converter 103). 
The audio signal supplied to the input terminal 102 is sampled at 48 kHz 
and is converted into the digital signal of 20 quantized bits (at the A/D 
converter 104). In the figure, for simplification, the audio signal input 
is represented by one channel but, in practice, four channel audio signal 
is supplied. The digitized video and four-channel audio signals are 
supplied to the digital recording signal processor 105. At the digital 
recording signal processor 105, the video and four-channel audio signals 
are time-base-processed and at the same time error-correcting codes are 
assigned to these signals in accordance with the format. The 
error-correcting codes are separately assigned to the respective video and 
four-channel audio signals. The digital recording signal processor 1005 
further performs digital modulation processing in accordance with a 
specified modulation system. The output signal of digital recording signal 
processor 105 is distributed to the recording and reproducing heads 112, 
113, 114, and 115, respectively, by the head selection switches 110 and 
111 via recording AMPs 106, 107 as well as recording/reproducing selecting 
switches 108, 109, and is recorded on a magnetic tape in accordance with 
the tape format shown in FIG. 2. In this system, the data rate after the 
error-correcting code assigning is 127 Mbit/sec, and in terms of video 
signal, the data for 1 field is divided to be recorded in 6 tracks. 
The recorded signal is reproduced as follows. The signal reproduced by the 
recording and reproducing heads 112, 113, 114, 115 enters to the digital 
reproducing signal processor 118 after being passed through head selection 
switches 110 and 111 as well as recording/reproducing selecting switches 
108 an 109 and amplified by the reproducing AMPs 116, 117. The digital 
reproducing signal processor 118 performs digital demodulation and 
error-correction decoding and the signal is decoded into the normal video 
signal data string and the 4-channel audio signal data string to be 
outputted. The output signal of digital reproducing signal processor 118 
is returned to the original video and 4-channel audio signals by the D/A 
converters 119, 120 and outputted via the output terminals 121, 122. 
FIG. 3 shows a schematic block diagram showing another conventional 
configuration of D-2 system digital VTR. Numeral 201 in the figure is an 
A/D converter which converts analog video and 4-channel audio signals into 
digital signals, respectively. A video signal processor 202, first audio 
signal processor 203a, second audio signal processor 203b, third audio 
signal processor 203c, and fourth audio signal processor 203d sample an 
output, digital signal from each A/D converter 201 at a specified 
frequency and output it to corresponding first digital signal processor 
204a and second digital signal processors 204b, 204b, 204b, 204b. Each of 
the digital signal processors 204a, 204b assigns error-correcting codes to 
the signal and then outputs it to a digital signal processor 206 via a 
switch 205. The digital signal processor 206 performs digital modulation 
processing on the input signal and then outputs the signal to a recording 
AMP 207. The recording AMP 207 amplifies the input signal. The amplified 
signal is recorded on a magnetic tape (not shown) by a recording and 
reproducing head 209 via a recording/reproducing selector switch 208. 
Numeral 210 is a reproduction unit which is so configured that the process 
is carried out in reverse sequence to that in the recording unit and 
therefore, the internal configuration of which is omitted. 
Because the D-2 system is standardized as a digital VTR for broadcasting, 
azimuth recording is performed without a guard band between tracks in the 
D-2 format. As shown in FIG. 2, the audio signal, video signal, and audio 
signal are arranged in this order in the head scanning direction and the 
audio signal is arranged in two channels each on the either edges of the 
track, forming a total of four channels. In the D-2 composite system, one 
line of the video signal is made to contain 910 samples by sampling at 4 
fsc, four times the subcarrier. After the 768 samples excluding the 
horizontal synchronizing signal are divided into two channels with 
vertical synchronizing signal being excluded, the samples in 1/3 of the 
field of 85 lines are collected and the order of 384.times.85.times.8 bit 
of data is rearranged by shuffling. An error-correcting code is assigned 
to the data and the data is recorded as a track pattern. FIG. 4 shows a 
format in which video signal area and audio signal area are 
error-correcting-encoded. The pixel data of one field is divided into 
three portions, separated into even numbered samples and odd numbered 
samples and recorded in separate tracks. One field consists of six tracks 
and the pattern format of each track is identical. 
Now, referring to FIG. 3, operations are briefly explained. The audio 
signal supplied to the input terminal is converted into 20-bit digital 
signal by the A/D converter 201. Sampling is performed at 48 kHz. The 
error-correcting codes are assigned separately to video signal and audio 
signal at digital signal processors 204a, 204b, respectively. Further, at 
the digital signal processor 206, digital modulation processing is 
performed in accordance with a specified modulation format. Output of 
digital signal processor 206 is passed through the recording AMP 207 as 
well as recording/reproducing selector 208, distributed to the recording 
and reproducing head 209 by the head selection switch (not shown), and 
recorded on a magnetic tape in accordance with a tape format. In this 
system, the data rate, after an error-correction code is assigned, is 127 
Mbit/sec and in terms of video signals, the data of 1 field is divided 
into 6 tracks to be recorded. 
As described above, because in this format, the audio signal is separately 
recorded in individual four channels, editing can be performed 
independently for each channel. In order to perform editing independently 
for each channel, a track format in which the audio signal of one channel 
is recorded as one area, in short, area dividing type track format, is 
required. Then, a gap between the areas is also required. In addition, 
because the video and audio signals differ in the data rate, the video 
signal area is large, while the audio signal is smaller than the video 
signal area. Consequently, in order to give the audio signal area error 
correction (capability equivalent to that of the video signal area, for 
example, in the D-2 format audio code (12, 8, 5) Reed-Solomon code may he 
so arranged that the codes keep an equal distance with each other as in 
video C2 code (68, 64, 5) Reed-Solomon codes. Wherein, (n, k, d) represent 
the code length by n, information length by k, and the distance between 
codes by d. However, the equivalent error-correcting capability may be 
obtained but the encoding efficiency becomes extremely poor; 8/12 for 
audio signal against 64/68 for video signal. 
Because the digital VTR for broadcasting apparatuses is configured as 
described above, it has appropriate qualities for business use such as 
high reliability, high picture quality, high sound quality, and highly 
sophisticated editing. Yet, on the other hand, because it, employs an area 
dividing type format as described above, a gaps must be provided and in 
addition, when the equal error correcting capabilities are given to both 
video and audio signals, the encoding efficiency of audio signal 
decreases. In home digital VTR, compactness and user-friendliness are 
strongly required as is the case with presently available VTR's equipped 
with a camera in the market. 
SUMMARY OF THE INVENTION 
One object of the present invention is to provide a digital signal 
recording and reproducing apparatus (digital VTR) which achieves excellent 
encoding efficiency and can perform audio signal editing. 
Another object of the present invention is to provide a digital signal 
recording and reproducing apparatus (digital VTR) which achieves 
compactness suited for domestic use as well and is easy to operate. 
In the digital signal recording and reproducing apparatus according to the 
first, invention, video and audio signals are integrated arid an 
error-correcting codes is assigned to them collectively when video and 
audio signals are digitally recorded in tracks on a magnetic tape. 
According to the first invention, the digitized video and audio signals 
which are separately arranged in one track are integrated and 
error-correcting codes are assigned to the integrated data. Thus, 
error-correction-encoding is effected. This process improves encoding 
efficiency of audio signal, gives equal error-correcting capabilities to 
video and audio signals, and makes it possible to form a more compact 
system. 
In the digital signal recording and reproducing apparatus according to the 
second invention, at least one track is designated as an exclusive track 
for post scoring when video and audio signals of one frame are divided to 
be recorded in plurality of tracks. Because at least one track is set 
exclusively for post-scoring in addition to tracks in which video and 
audio signals are recorded during normal recording, the error-correcting 
code for the post-scoring signal achieves the equivalent level to those 
for other tracks, (and obtains the equivalent error correcting 
capability,) improving the encoding efficiency as well as making 
post-scoring editing possible. Even if post-scoring audio recording is 
repeated many times, the audio signal recorded during normal recording is 
not erased and thus, operational capability during post-scoring audio 
recording is improved. 
In the digital signal recording and reproducing apparatus according to the 
third invention, a part of video signal extracted in the second invention 
is recorded in the track designated for post-scoring during normal 
recording. Consequently, because a part of video signal can be recorded in 
an area different from the area where video signal is normally recorded, 
video signal of better picture quality can be recorded and reproduced. 
In the digital signal recording and reproducing method of the fourth 
invention, video and audio signals which are divided and arranged in one 
track are integrated an error-correcting code is assigned to this 
integrated data. Referring to one track, there are only two recording 
areas, permitting only one place to provide a gap; this improves the 
recording efficiency. When the number of audio channels is further 
increased for recording, error-correction codes are assigned to another 
area to carry out recording. Thus, encoding efficiency of audio signal is 
further improved, the error-correction capabilities for video and audio 
signals are brought to the equal level, thereby making it possible to form 
a more compact system. 
In the digital signal recording anti reproducing method of the fifth 
invention, post-scoring audio signal is recorded in an area different from 
the main video recording area after an error-correcting codes is assigned. 
The error-correcting code of post-scoring audio signal becomes equal to 
that of the main recording area and the encoding efficiency can be 
improved with the error-correcting capabilities being brought to the 
equivalent level, and at, the same time post-scoring editing is made 
possible. Even if post-scoring audio recording fails, the audio signal 
recorded during normal recording is not erased, improving, operational 
capability post-scoring audio recording. 
The digital signal recording and reproducing method according to the sixth 
invention, concerns the normal recording at the fifth invention, wherein a 
part of the extracted video signal is recorded in an area different from 
the main video recording area. Since a part of video signal is recorded in 
an area different, from the main video recording area. Since a part of 
video signal is recorded in an area different from an area where video 
signal is normally recorded, video signal of higher picture quality can be 
recorded and reproduced. 
In the digital signal recording and reproducing method of the seventh 
invention, first and second signal are error-correcting-encoded 
respectively, and the inspection codes are recorded in the tracks in a 
lump. A gap between first and second signals in the track is no longer 
needed and the encoding efficiency is improved. 
In The digital signal recording and reproducing method of the eighth 
invention, error-correcting-encoded audio signal is recorded in the second 
sign the track in which the second signal is recorded when the second 
signal is rewritten in the seventh invention. Therefore, it is possible to 
perform rewriting without changing error-correcting capability for the 
second signal. 
In the digital signal recording and reproducing method of the ninth 
invention, first and second signals are separately 
error-correcting-encoded and recorded in tracks, and code length of the 
error-correcting code for the signal to be rewritten is changed when first 
or second signals are rewritten. Consequently, it, is possible to adjust 
the error-correcting capability of the signal to be rewritten. 
In the digital signal recording and reproducing method according to the 
tenth stage of the invention, the code length of error-correcting code for 
the signal to be rewritten in the ninth invention is shortened. 
Consequently, the signal which is not rewritten can be stored, being kept 
intact. 
In the digital signal recording and reproducing method of the eleventh 
invention, the first and second signals in the seventh, eighth, and ninth 
inventions are a video signal and an audio signal, respectively. The 
portion corresponding to the gap is assigned to the error-correcting code 
for the audio signal to improve the error-correcting capability of the 
audio signal. 
In the digital signal recording and reproducing method of the twelfth 
invention, the first and second signals in the seventh, eighth and ninth 
embodiment are an audio signal and a subcode signal, respectively. The 
portion corresponding to the gap is assigned to the error-correcting code 
for the subcode signal to improve the error-correcting capability of the 
subcode signal. 
In the digital signal recording and reproducing method of the thirteenth 
invention, during normal recording, video and audio signals are 
independently error-correcting-encoded, and are recorded in a track with a 
gap being set in it. When post-scoring audio recording is performed, audio 
and INDEX signals are error-correcting-encoded in a lump and are recorded 
in a track. In this configuration, a gap between audio and INDEX signals 
is no longer needed and the encoding efficiency is improved. 
In the digital signal recording and reproducing method of the fourteenth 
invention during normal recording video and audio signals are 
error-correcting-encoded in a lump and recorded in a track, and when audio 
and INDEX signals are rewritten during post-scoring sound recording the 
audio and INDEX signals to be rewritten are error-correcting-encoded in a 
lump and recorded in a track. In this configuration, the signal can be 
rewritten without deteriorating the error-correcting capabilities of the 
portion to be rewritten and without increasing redundancy. 
The above and further objects and features of the invention will more fully 
be apparent from the following detailed description with accompanying 
drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring to the drawings, embodiments of the present invention will be 
described in detail hereinafter. 
(First Embodiment) 
FIG. 5 is a schematic block diagram showing an embodiment of home digital 
VTR according to the present invention. In FIG. 5, numeral 1 is an input 
terminal for a video signal, and via the input terminal 1, the analog 
video signal is supplied to an A/D converter 3, and the A/D converter 3 
converts the signal to a digital signal and outputs the signal to a 
digital recording signal processor 5. On the other hand, numeral 2 is an 
input terminal for an audio signal, and via the input terminal 2, the 
analog audio signal is supplied to an A/D converter 4, and the A/D 
converter 4 converts the signal to a digital signal and outputs the signal 
to the digital recording signal processor 5 and a post-scoring audio 
recording signal processor 6. The post-scoring audio recording signal 
processor 6 sends dummy data to the digital recording signal processor 5 
during normal recording and the audio signal for post-scoring to the 
digital recording signal processor 5 during post-scoring audio recording. 
The digital recording signal processor 5 assigns error-correcting codes to 
the video and audio signals in a lump and outputs the 
error-correcting-encoded signal to a digital modulation processor 7. The 
digital recording signal processor 5 separately extracts high-frequency 
components from the input video signal using, for example, a band limiting 
filter. The digital modulation processor 7 performs digital modulation and 
other processing and outputs the processed signal to recording AMP's 8, 9. 
The recording AMP's 8, 9 amplify the input signal. The amplified signal is 
distributed to four recording and reproducing heads 14, 15, 16, 17 via 
recording/reproducing selector switches 10, 11 and via head selector 
switches 12, 13, and is recorded on a magnetic tape (not shown). Numerals 
18-27 show components of the reproduction unit and reproducing AMPs 18, 19 
amplify the reproduced signal which is reproduced by recording and 
reproducing heads 14, 15, 16, 17 and is supplied via switches 12, 13 and 
10, 11, and output the amplified signals to a digital demodulation 
processor 20. The digital demodulation processor 20 performs digital 
demodulation and other processings and outputs the processed signal to a 
digital reproducing signal processor 21. The digital reproducing signal 
processor 21 performs processings such as error-correcting-encoding and 
outputs the video signal of the normal signal string to a D/A converter 
24, while it outputs the audio signal to a D/A converter 25 via a 
post-scoring selector switch 23 luring normal recording and via the 
post-scoring audio reproducing signal processor 22 and the post-scoring 
audio selector switch 23 during post-scoring audio recording. The D/A 
converter 24 converts the input signal to the original analog video signal 
and outputs it via an output terminal 26. The D/A converter 25 converts 
the input signal to the original analog audio signal and outputs it via an 
output terminal 27. 
FIG. 6 shows an example of a tape format of a digital VTR according to the 
present invention. As shown in FIG. 6, in the system according to the 
present, invention, the video signal and the four-channel audio signal are 
digitally recorded in a track tilted in the longitudinal direction of a 
magnetic tape in the same manner as in the conventional case, but in the 
present system, 10 tracks are provided for the time required for one frame 
of video signal, the video signal and the two-channel audio signal are 
divided and arranged in the nine tracks, and in the remaining one track, 
the two-channel audio signal and a reserve signal (hereinafter called 
"reserve data") are arranged to be recorded. An area designated for 
recording of control signal for tape feed (hereinafter called "ATF 
signal") and TNDEX signal is set in each track. 
Now referring to FIG. 5, operations will be described. First, operations in 
normal recording is described. The composite signal supplied to the input 
terminal 1 is quantized to 8-bit digital signal at quadruple subcarrier 
frequencies (14.318 MHz) at, the A/D converter 3. The audio signal 
supplied to the input terminal 2 is quantized to 16-bit digital signal at 
48 kHz at, the A/D converter 4. In FIG. 5, the audio signal input is shown 
in one channel for simplification but, in practice, there are two-channel 
audio inputs. The video signal and 2-channel audio signal which are 
digitized are supplied to the digital form are supplied to the digital 
recording signal processor 5. 
On the other hand, at the post-scoring audio recording signal processor 6, 
dummy data is formed and is sent to the digital recording signal processor 
5 as normal recording is performed. 
At the digital recording signal processor 5, the video signal is 
image-compressed to reduce the data rate of video signal and necessary 
time-base processing is performed on image-compressed video signal and 
2-channel audio signal, which then are divided and arranged in the 
designated nine tracks of the ten tracks per one frame. To the remaining 
one track, the dummy data input through the post-scoring audio recording 
signal processor 6 or data of gh-frequency components extracted from the 
above-mentioned video signal at the digital recording signal processor 5 
is arranged. By the way, whether to arrange the dummy data input, through 
the post-scoring audio recording signal processor 6 or the data of 
high-frequency component extracted from the above-mentioned video signal 
to the remaining one track is decided by the image quality selector key 
(not shown) and the information about which signal is arranged is recorded 
with the INDEX signal flag. In addition, an error-correcting code is 
assigned to each track. The data string to which the error-correcting code 
is assigned is sent out to the digital modulation processor 7. 
By integrating video and audio signals during normal recording as described 
above and performing error-correcting-encoding in which the 
error-correcting codes is assigned to the overall integrated data 
simultaneously, it is possible to form codes with better encoding 
efficiency and higher correcting capability compared to the conventional 
process in which the error-correcting code is assigned separately to video 
and audio signals. Particularly, since the video signal has larger volume 
of data than audio signal, this configuration is extremely effective for 
the audio signal. 
At the digital modulation processor 7, the INDEX signal is assigned to each 
track of the data string sent out from the digital recording signal 
processor 5, while digital modulation is performed in accordance with a 
specified modulation system. In addition, to each track of the 
digital-modulated data string, the AFT signal is assigned. 
The output signal of the digital modulation processor 7 is passed through 
recording AMPs 8, 9, distributed to recording and reproducing heads 14, 
15, 16, 17, respectively, by head selector switches 12, 13 and 
recording/reproducing selector switches 10, 11, and are recorded on a 
magnetic tape in accordance with the tape format shown in FIG. 6. 
Signal reproduction is performed as follows. The signal reproduced by 
recording and reproducing heads 14, 15, 16, 17 is passed through head 
selector switches 12, 13 and through recording/reproducing switches 10, 
11, amplified at, reproducing AMPs is, 19, and then, supplied to the 
digital demodulation processor 20. At the digital demodulation processor 
20, the ATF signal is extracted from each track and sent out to the servo 
circuit (not shown) while the data string of each track is 
digital-demodulated. The digitally demodulated data string is sent to the 
digital reproducing signal processor 21. 
At the digital reproducing signal processor 21, error-correcting processing 
is performed on the digital-demodulated data string to be entered. In 
addition, the video signal and 2-channel audio signal are extracted from 
designated nine tracks out of a 10-track unit, and at the same time, when 
the INDEX signal indicates that post-scoring audio data is recorded, the 
data of the remaining one track of a 10-track unit is sent out to 
post-scoring audio reproducing signal processor 22. The extracted video 
signal is restored to the original video signal by compression-restoration 
processing. When the INDEX signal indicated high-frequency component data 
of video signal is recorded, the data of the remaining one track of a 
10-track unit and this compression-restored video data are added to 
restore the original video signal. The extracted 2-channel audio signal is 
restored to the original 2-channel audio signal by a specified time-base 
processing. 
As described above, by recording high-frequency component data, which is a 
part of video signal, in other recording area than that for normal video 
signal, higher image-quality video signal can be reproduced. 
At the post-scoring audio reproducing signal processor 22, the input data 
from the digital reproducing signal processor 21 is identified as dummy 
data. This identification process can determine that there is no audio 
data for post-scoring in this track. The configuration is designed to 
allow the post-scoring audio selector switch 23 to constantly select audio 
data from the digital reproducing signal processor 21 by this judgment. 
Thus, consideration is given so that users can select and listen to 
post-scored sound by post-scoring audio selector key (not shown) and that, 
if post-scoring sound is not recorded even when users select post-scoring 
sound, normal sound is outputted automatically. If any post-scoring audio 
signal is recorded on a magnetic tape, the input data from the digital 
reproducing signal processor 21 contains 2-channel audio signals for 
post-scoring, Therefore, time-base processing is carried out at this 
post-scoring audio reproducing signal processor 22 and the audio signal is 
restored to the original 2-channel audio signal for post-scoring to be 
sent out. It is also possible to decide whether any post,-scoring audio 
signal is recorded or not, by setting a flag in INDEX signal. 
The video signal sent out, from is digital reproducing signal processor 21 
is D/A-converted by the D/A converter 24 to the original video signal. If 
no post-scoring sound is selected by users using the post-scoring audio 
selector key, the 2-channel audio signal sent out from the digital 
reproducing signal processor 21 is D/A converted by the D/A converter 25 
via post-scoring audio selector switch 23 and the original 2-channel audio 
signals is reproduced. If users select post-scoring sound by the 
post-scoring audio selector key and the 2-channel audio signal for 
post-scoring is reproduced, the 2-channel audio signal for past-scoring 
sent out from the post-scoring audio reproducing signal processor 22 is 
D/A-converted by the D/A converter 25 via post-scoring audio selector 
switch 23 and the original 2-channel audio signal for post-scoring can be 
obtained. Though it is not, shown in the figure, the configuration is so 
designed that if no reproduced outputs are obtained from reproducing AMPs 
18, 19, the output, video and audio signals are muted. 
Next, operation in post-scoring audio recording will be described. By 
operating a post-scoring recording key (not, shown), post-scoring 
recording mode is obtained. By operating a reproducing key (not shown) at 
a post-scoring recording mode, post-scoring audio recording starts after a 
specific time. At post-scoring recording mode, at the post-scoring audio 
recording processor 6, input two-channel audio signal is 
time-base-processed arid is divided and arranged in designated track of a 
track array of 10 tracks. This data is sent to the digital recording 
signal processor 5. 
By operating the reproducing key, a magnetic tape begins running. Running 
of a magnetic tape is controlled, using the ATF signal reproduced from 
each track. Video and 2-channel audio signals reproduced from designated 
nine tracks of a track array of 10 tracks are signal-processed in the same 
manner as in normal reproduction and the reproduced video signal is 
outputted through the output, terminal 26. After the reproducing key is 
operated, post-scoring audio recording is resumed from a specified 
position of a magnetic tape. 
The two-channel audio signal for post-scoring sent, out from the 
post-scoring audio recording processor 6 is signal processed as in normal 
recording at the digital recording signal processor 5 and digital 
modulation processor 7 and is supplied to the recording AMP 9. The 
two-channel audio signal is overwritten to be recorded in a designated 
track of a track array of 10 tracks on a magnetic tape by changing over 
properly either recording/reproducing selector switch 11 and head selector 
switch 13. Thus, post-scoring audio 
When DCT (Discrete Cosine Transform) encoding is used as image compressing 
system to reduce video data rate to about 25 Mbps, and when a system in 
which the error-correcting code is assigned independently to the video 
signal and two-channel audio signal, as in a conventional system, is 
employed, recording data rate after error-correcting code assigning 
reaches about 38 Mbps. On the other hand, according to the system in the 
first embodiment, recording data rate of about 38 Mbps, the similar level 
that can be achieved with the conventional system, can be achieved even 
when video and two-channel audio signals during normal recording are 
integrated with the error-correcting code assigned to them, and then, the 
two-channel audio signal for post-scoring, which is integrated with the 
reserve signal with the error-correcting code assigned to them are added. 
Unlike apparatuses for business use, in apparatuses for private use, 
user-friendliness is essential. Consequently, audio signal is not 
necessarily recorded and reproduced channel by channel and may be recorded 
and reproduced by the unit of two channels. 
In this embodiment, video and audio signals for one frame are divided and 
arranged in a track array of 10 tracks but video and audio signal for one 
frame may be divided and arranged in a track array of N tracks (N 
represents a positive integer) depending on the type of input video signal 
(for example, NTSC, , etc. ) or electromagnetic performance of magnetic 
tape and magnetic head. 
In this embodiment, one track out of a track array of 10 tracks is 
designated as at track exclusively for post-scoring but, plurality of 
tracks may be designated. 
According to this first embodiment, since during normal recoding, thief 
video signal is recorded together with the two-channel audio signal and 
during post-scoring audio recording, the two-channel audio signal is 
recorded in a track designated for post-scoring audio recording, even if 
users fail in post-scoring audio recording, the two-channel audio signal 
recorded during normal recording is not erased, allowing users to repeat 
post-scoring audio recording over and over, a system friendly to users can 
be constructed. 
(Second Embodiment) 
FIG. 7 is a schematic block diagram showing another configuration of at 
home digital VTR according to the present invention, while FIG. 8 is a 
diagram showing a tape format in accordance with the embodiment. First of 
all, during normal recording of video/audio signals, the video signal is 
supplied to a video signal processor 52 via an A/D converter 51, sampled 
at 4 fsc, time-base-processed, data-compressed by DCT if compression is 
needed, and then, outputted two a first digital signal processor 54a. In 
the meantime, the audio signal passed through an A/D converter 51 is 
sampled and digitized at, a first audio signal processor 53a and 
out-putted to the first, digital signal processor 54a. At the first 
digital signal processor 54a, the video and audio signals are integrated 
and the error-correcting code is assigned to them collectively. The 
error-correcting-encoded data is recorded as magnetized pattern in area A 
on a magnetic tape shown in FIG. 8 by a recordings and reproducing head 59 
via a switch 55, a digital modulation processor 56, a recording AMP 57, 
and a recording/reproducing selector switch 58. In the remaining area B, 
dummy data supplied from a second audio signal processor 53b or 
high-frequency component data extracted from the above-mentioned video 
signal and supplied from the video signal processor 52 is sent from the 
second digital signal processor 54b to be recorded. 
On the other hand, during post-scoring audio recording, the two-channel 
audio signals for post-scoring passed through an A/D converter 51 pass the 
second audio signal processor 53b and are error-correcting-encoded by the 
second digital signal processor 54b. The error-correcting-encoded data is 
recorded as magnetized pattern in area B on a magnetic tape shown in FIG. 
8 by recording and reproducing head 59 as in normal recording. 
Other details of the operation-during recording are same as those described 
in the above first embodiment, and therefore, the description is omitted. 
In reproducing operation, the process takes steps reversal to those in 
recording, and therefore, the description is also omitted. 
In the format, shown in FIG. 8, the video and four-channel audio signals 
are digitally recorded in a track tilted in the longitudinal direction of 
a magnetic tape as in conventional embodiments. In area A, the video and 
two-channel audio signals are divided and arranged, while in area B, the 
two-channel audio signal and reserve data are arranged and recorded. The 
area designated for recording of ATF and INDEX signals are set in each 
track. Because video and audio signals can be error-correcting-encoded in 
a lump during normal recording, highly efficient code correction is 
achieved. A gap used for recording video and audio signals separately is 
no longer needed. In addition, it has an advantage that post-scoring area 
can be freely used for signals other than post-scoring audio signal due to 
this format. 
FIG. 9 shows a format, in which video and audio data are error-correcting 
encoded according to the second embodiment and a format in which 
post-scoring audio data is error-correcting-encoded, respectively. As the 
comparison with the conventional method illustrated in FIG. 4, in the 
information area consists of D-2 format video and audio data the data 
volume amounts to 85.times.64+85.times.8.times.4=8160 bytes and in the 
overall format in which these data are encoded the data volume amounts to 
93.times.68+93.times.12.times.4=10788 bytes. On the other hand according 
to the embodiment shown in FIG. 8, the information area consists of the 
same number of bytes, with 85.times.80+85.times.16=8160 bytes, but the 
total of the encoded data amounts to 93.times.84+93.times.20=9672 bytes, 
which is 1116 bytes less than that of the conventional system. The random 
error-correcting capabilities may be the same because the synthetic 
distance is 9.times.5=45 for both cases if Reed-Solomon code on GF 
(2.sup.8) is used. The burst correcting capabilities are equal also. 
Consequently, the present, invention is superior in nearly identical 
correcting capability can be obtained with less redundancy. 
In this embodiment, a single area B in the track is designated as an 
exclusive area for post-scoring but plurality of areas may be provided for 
the purpose. 
As described above, in this second embodiment, video and audio signals are 
error-correcting-encoded in a lump, and are recorded in a fixed area on a 
track while the post-scoring audio signal is error-correcting-encoded 
separately and is recorded in a different area on the track. Therefore, 
only one place is required to provide a lap clearance compared to the 
conventional system, a system with high error-correcting encoding 
efficiency, less possibility of post-scoring recording failure, and higher 
efficiency can be constructed. 
A track designated for post-scoring and an area B designated for 
post-scoring in the first and the second embodiments can be used for 
various applications including, for example, recording a high-quality 
still image signal as shown, in the Japanese Patent Application No. 
Y-2-48465 "Animation/still Picture Simultaneous Recording and Reproducing 
Apparatus." 
Next, another embodiment of the present invention will be explained below. 
The configuration of the digital VTR in each embodiment shown below is the 
same as FIG. 5 (first embodiment). 
(Third Embodiment) 
FIG. 10 is a diagram showing a tape format according to the third 
embodiment. In the system according to thief third embodiment as shown in 
FIG. 10, three areas are provided so that ATF signal, special recording 
area signal of INDEX signal (example of subcode signal), video signal and 
two-channel audio signal are digitally recorded sequentially in the head 
scanning direction. Between thee ATF and INDEX areas and the INDEX and the 
video +audio areas, a gap is provided, respectively. 
In the digital recording signal processor 5, as described above, the video 
signal is image-compressed, and necessary time-base processing is 
performed on the image-compressed video signal and the two-channel audio 
signal. Then, the signals are divided and arranged, for example, in ten 
tracks per one frame. And error-correcting encoding is performed in each 
track but encoding is performed on video, audio, and INDEX signals, 
separately. Then, data such as the signal for retrieval and the number of 
channels of audio signal is recorded in the INDEX signal. The data string 
to which the error-correcting code is assigned is sent out to the digital 
modulation processor 7. At the digital modulation processor 7, the ATF 
signal is added to each track of the data string sent from the digital 
recording signal processor 5 and digital modulation is performed in 
accordance with a specified modulation system. The ATF signal may he added 
after modulation is carried out. 
Now, the error-correcting code for data to be recorded on a magnetic tape 
will be explained using FIG. 12. FIG. 12 (a) shows a configuration of the 
error-correcting code for video and audio signals during normal recording. 
The error-correcting code is, in general, frequently- dual-encoded, and in 
such case, after outer encoding (also called C2 encoding) is performed on 
each data, inner encoding (also called C1 encoding) is performed. Now, the 
audio and video data are two-dimensionally arranged in k.sub.1 
.times.k.sub.2 and in k.sub.1 .times.k.sub.3, respectively. The audio 
signal is encoded into C1: (n.sub.1, k.sub.1, d.sub.1), C2: (n.sub.2, 
k.sub.2, d.sub.2), and the video signal is encoded into C1: (n.sub.1, 
k.sub.1, d.sub.1), C2: (n.sub.3, k.sub.3, d.sub.3), where n is a code 
length, k is an information length, and d is a distance between codes. The 
encoded data is scanned from the lower left to the right in FIG. 12 (a) 
and forms a track by repeating this operation n.sub.2 +n.sub.3 times. In 
FIG. 10, outer encoded area is shown as inspection data. On the INDEX 
signal, similar error-correcting coding is performed (not, shown). As 
shown in FIG. 12 (a), because no gap is provided between audio inspection 
data (outer code) and video inspection data (outer code), the length of 
the inspection(code can be increased by the gap length, and thus, the 
error-correcting capability can be improved. 
The audio data for post-scoring is error-correcting-encoded as in normal 
recording. At the track in FIG. 10, audio data and audio inspection data 
are rewritten. The rewriting timing is determined by estimating from the 
timing to reproduce ATF and INDFX signals and obtaining the recording 
mode. Consequently, positioning is performed properly but not accurately, 
and part of the video inspection data may he impaired. However, because 
for normal video data, a strong error-correcting code is used, errors of 
only one or two inner codes may occur, almost all of such errors can be 
corrected. Even if correction is impossible, errors are occurred in the 
inspection data and video data is scarcely affected. 
(Fourth Embodiment) 
Using a track pattern diagram in FIG. 11, the fourth embodiment will be 
explained. The track (a) in FIG. 11 shows a track pattern during normal 
recording and is the same as that in FIG. 10. When post-scoring audio 
recording is carried out, a gap 3 is created by shortening the code length 
of the audio signal as shown in the track (b). That, is, as shown in FIG. 
12 (b), by shortening the code length of the outer code (C2) gap 3 can be 
produced. In this case, the correcting capability for the audio data is 
lowered but no video data is damaged. The gap 3 exists in the same manner 
as in conventional embodiments and the same correcting capability is 
obtained for the audio signal. Because almost all portions to be 
post-scored are usually a part of the recorded signal, the remaining part 
of the audio data can be stored with high correcting capability ensured. 
In addition, if post-scoring audio signal is not normally reproduced, 
post-scoring can be done over again. 
Information that the post-scoring code length is changed should be stored 
in the very place after synchronizing and ID signals are added, when, for 
example, one of C1 codes in FIG. 12 (a) are formed as an ID signal. In 
FIG. 5, this ID signal is detected and processing of audio signal can be 
performed at the post-scoring audio reproducing signal processor 22. 
When the code length for audio signal is varied, by shortening the code 
length the gap 3 can be produced and it is convenient but conversely, by 
increasing the code length it is also possible to improve the 
error-correcting capability. This is effective when the error rate during 
post-scoring audio recording is higher than that during normal recording. 
(Fifth Embodiment) 
Using a track pattern diagram in FIG. 13, the fifth embodiment will be 
explained. In the track (a) in FIG. 13, the audio signal and INDEX signal 
are error-correcting-encoded in a lump. This brings a condition in which 
gap 2 is not present. Now, the case in which the INDEX signal is 
post-scored is considered. As in the case of the track (b) in FIG. 13, by 
recording the INDEX signal of shortened code length the sap 2 can be 
produced. In this case, the audio signal in the back is not affected at 
all. The INDEX signal is rewritten when, for example, the retrieval signal 
is 
(Sixth Embodiment) 
FIG. 14 shows a track format on a magnetic tape during normal recording 
according to the sixth embodiment and FIG. 15 shows a track format on a 
magnetic tape during post-scoring audio recording. FIG. 16 shows an 
error-correcting code format during normal recording according to the 
sixth embodiment and FIG. 17 shows an error-correcting code format during 
post-scoring audio recording. In the system used in the sixth embodiment 
as shown in FIGS. 14, 16, four areas are provided during normal recording, 
in which the ATF signal, the special recording area signals for INDEX 
signal, the audio signal, and the video signal are digitally recorded in 
that order in the head scanning direction. Between the ATF area and INDEX 
area and the audio area and video area, gaps 1, 2, 3 are provided 
respectively. On the other hand, during post-scoring audio recording as 
shown in FIGS. 15, 17, the inner-code and outer-code inspection data are 
added to the INDEX signal and audio signal in a lump, and gaps 1, 4 are 
provided between the ATF and INDEX areas and the audio and video areas, 
respectively, reducing the gap by one compared to normal recording. Thus, 
adjustment of timing difference caused by post-scoring is effected. 
(Seventh Embodiment) 
FIG. 18 shows a track format on a magnetic tape according to the seventh 
embodiment during normal recording, and FIG. 19 shows a track format on a 
magnetic tape during post-scoring audio recording. FIG. 20 shows an 
error-correcting code format according to the seventh embodiment during 
normal recording, and FIG. 21 shows an error-correcting code format during 
post-scoring audio recording. During normal recording as shown in FIGS. 
18, 20, the audio signal and video signal are error-correcting-encoded in 
a lump. In this case, there is no gap between audio and video signals. 
Now, consideration is given to the case in which the audio signal is 
post-scored. As shown in FIGS. 19, 21, by recording INDEX and audio 
signals in a lump a gap can be produced. In this case, the video signal in 
the back in not affected at all. 
In the above third through seventh embodiments, process is explained with 
video, audio, and INDEX signals as examples, but the same explanation will 
be applied to any data if they are related to one another. 
In each embodiment, two-channel audio signal for normal recording and 
two-channel audio signal for post-scoring are designed to be recorded 
without audio-compression, but they may be audio-compressed and recorded 
and they are not necessarily two-channel signals. 
In each embodiment, the input video signal is designed to be quantized to 
an 8-hit digital signal at quadruple sub-carrier frequency (14.318 MHz) at 
the A/D converter, but it, may be a 4:2:2 component video signal as seen 
in CCIR Rec601. 
In each embodiment, the input audio signal is designed to be converted into 
a 16-bit digitized signal with sampling frequency of 48 kHz at the A/D 
converter, but it may be so configured to be converted, for example, to a 
12-bit digitized signal with sampling frequency of 32 kHz, or to a 16-bit 
digitized signal with sampling frequency of 44.1 kHz. 
In each embodiment, a part of video signal to be extracted is explained 
using a high-frequency component but needless to say, it may be a 
low-frequency component, DC component, data for motion compensation, or 
data for editing or special reproduction. 
As this invention may be embodied in several forms without departing from 
the spirit of essential characteristics thereof, the present embodiment is 
therefore illustrative and note restrictive, since the scope of the 
invention is defined by the appended claims rather than by the description 
preceding them, and all changes that fall within metes and bounds of the 
claims, or equivalence of such metes and bounds thereof are therefore 
intended to be embraced by the claims.