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Claims  |
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What is claimed is:
1. A method of recording a digital image signal which has a recording
format including a recording area for a coded image signal and another
recording area for incident information, the recording area for incident
information having a pack structure which includes a header pack for
recording line designation data designating an arbitrary line of the image
signal and a parameter regarding coding of the recording signal and a data
pack for recording data obtained by coding a signal of a line designated
by the header pack in accordance with the parameter, comprising the steps
of:
coding and recording the image signal into the recording area for an image
signal;
recording data designating a predetermined line of a copyright protection
signal inserted in the predetermined line of the image signal and a
parameter regarding coding of the copyright protection signal into the
header pack; and
recording the coded copyright protection signal into the data pack.
2. A digital image signal recording apparatus for recording a digital image
signal which has a recording format including a recording area for a coded
image signal and another recording area for incident information, the
recording area for incident information having a pack structure which
includes a header pack for recording line designation data designating an
arbitrary line of the image signal and a parameter regarding coding of the
recording signal and a data pack for recording data obtained by coding a
signal of a line designated by the header pack in accordance with the
parameter, comprising:
means for coding and recording the image signal into the recording area for
an image signal; and
means for recording data designating a predetermined line of a copyright
protection signal inserted in the predetermined line of the image signal
and a parameter regarding coding of the copyright protection signal into
the header pack and recording the coded copyright protection signal into
the data pack.
3. A digital image signal recording apparatus as claimed in claim 2,
wherein information instructing that same contents should be restored in
same lines of a first field and a second field of the image signal is
recorded into the header pack so that only one of the fields of the
copyright protection signal having the same contents in the same lines of
the first field and the second field is coded and recorded into the data
pack.
4. A digital image signal recording apparatus as claimed in claim 2,
wherein, when the copyright protection signal is to be coded, a portion of
the image signal higher than a pedestal level is quantized finely.
5. A method of reproducing a digital image signal which has a recording
format including a recording area for a coded image signal and another
recording area for incident information, the recording area for incident
information having a pack structure which includes a header pack for
recording line designation data designating an arbitrary line of the image
signal and a parameter regarding coding of the recording signal and a data
pack for recording data obtained by coding a signal of a line designated
by the header pack in accordance with the parameter, the coded image
signal being recorded in the recording area for an image signal, data
designating a predetermined line of a copyright protection signal inserted
in the predetermined line of the image signal and a parameter regarding
coding of the copyright protection signal being recorded in the header
pack, the coded copyright protection signal being recorded in the data
pack, comprising the steps of:
reading the coded image signal from the recording area for an image signal
and decoding the read out image signal;
reading the header pack and the data pack to restore the copyright
protection signal; and
inserting the restored copyright protection signal into the predetermined
line of the decoded image signal.
6. A digital image reproduction apparatus for reproducing a digital image
signal which has a recording format including a recording area for a coded
image signal and another recording area for incident information, the
recording area for incident information having a pack structure which
includes a header pack for recording line designation data designating an
arbitrary line of the image signal and a parameter regarding coding of the
recording signal and a data pack for recording data obtained by coding a
signal of a line designated by the header pack in accordance with the
parameter, the coded image signal being recorded in the recording area for
an image signal, data designating a predetermined line of a copyright
protection signal inserted in the predetermined line of the image signal
and a parameter regarding coding of the copyright protection signal being
recorded in the header pack, the coded copyright protection signal being
recorded in the data pack, comprising:
means for reading the coded image signal from the recording area for an
image signal and decoding the read out image signal; and
means for reading the header pack and the data pack to restore the
copyright protection signal and inserting the restored copyright
protection signal into the predetermined line of the decoded image signal.
7. A method of recording and reproducing a digital image signal which has a
recording format including a recording area for a coded image signal and
another recording area for incident information, the recording area for
incident information having a pack structure which includes a header pack
for recording line designation data designating an arbitrary line of the
image signal and a parameter regarding coding of the recording signal and
a data pack for recording data obtained by coding a signal of a line
designated by the header pack in accordance with the parameter, comprising
the steps of:
recording the image signal, the recording step including the steps of
coding and recording the image signal into the recording area for an image
signal, recording data designating a predetermined line of a copyright
protection signal inserted in the predetermined line of the image signal
and a parameter regarding coding of the copyright protection signal into
the header pack, and recording the coded copyright protection signal into
the data pack; and
reproducing the image signal, the reproduction step including the steps of
reading the coded image signal from the recording area for an image signal
and decoding the read out image signal, reading the header pack and the
data pack to restore the copyright protection signal, and inserting the
restored copyright protection signal into the predetermined line of the
decoded image signal.
8. A digital image signal recording and reproduction apparatus for
recording and reproducing a digital image signal which has a recording
format including a recording area for a coded image signal and another
recording area for incident information, the recording area for incident
information having a pack structure which includes a header pack for
recording line designation data designating an arbitrary line of the image
signal and a parameter regarding coding of the recording signal and a data
pack for recording data obtained by coding a signal of a line designated
by the header pack in accordance with the parameter, comprising:
means for coding and recording the image signal into the recording area for
an image signal;
means for recording data designating a predetermined line of a copyright
protection signal inserted in the predetermined line of the image signal
and a parameter regarding coding of the copyright protection signal into
the header pack and recording the coded copyright protection signal into
the data pack;
means for reading the coded image signal from the recording area for an
image signal and decoding the read out image signal; and
means for reading the header pack and the data pack to restore the
copyright protection signal and inserting the restored copyright
protection signal into the predetermined line of the decoded image signal.
9. A digital image signal recording and reproduction apparatus as claimed
in claim 6, wherein information instructing that same contents should be
restored in same lines of a first field and a second field of the image
signal is recorded into the header pack so that only one of the fields of
the copyright protection signal having the same contents in the same lines
of the first field and the second field is coded and recorded into the
data pack.
10. A digital image signal recording and reproduction apparatus as claimed
in claim 6, wherein, when the copyright protection signal is to be coded,
a portion of the image signal higher than a pedestal level is quantized
finely.
11. A recording medium on which a digital image signal is recorded, the
image signal having a recording format including a recording area for a
coded image signal and another recording area for incident information,
the recording area for incident information having a pack structure which
includes a header pack for recording line designation data designating an
arbitrary line of the image signal and a parameter regarding coding of the
recording signal and a data pack for recording data obtained by coding a
signal of a line designated by the header pack in accordance with the
parameter, the coded image signal being recorded in the recording area for
an image signal, data designating a predetermined line of a copyright
protection signal inserted in the predetermined line of the image signal
and a parameter regarding coding of the copyright protection signal being
recorded in the header pack, the coded copyright protection signal being
recorded in the data pack.
12. The method of claim 1, wherein the parameter identifies a number of
samples included in data packs following said header pack in said incident
information.
13. The method of claim 1, wherein said incident information includes packs
of data each having a common pack structure, said header pack and said
data pack of said incident information each having the common pack
structure.
14. The method of claim 1, wherein said data pack includes a plurality of
data representing a copy protection signal that is to be coded in
accordance with said parameter and inserted in the image signal in a line
designated by said header pack.
15. The method of claim 5, wherein the parameter identifies a number of
samples included in data packs following said header pack in said incident
information.
16. The method of claim 5, wherein said incident information includes packs
of data each having a common pack structure, said header pack and said
data pack of said incident information each having the common pack
structure.
17. The apparatus of claim 5, wherein said data pack includes a plurality
of data representing a copy protection signal that is to be coded in
accordance with said parameter and inserted in the image signal in a line
designated by said header pack. |
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Claims |
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Description |
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BACKGROUND OF THE INVENTION
This invention relates to a digital image recording and/or reproduction
method and an apparatus by which a digital image signal is coded and
recorded on a recording medium and/or read and decoded for reproduction.
On a software tape for use with an analog video tape recorder, a signal is
recorded so as to disturb operation of an AGC (Automatic Gain Control) of
a recording amplifier of a video tape recorder. The disturbing signal is
inserted in a predetermined line within a vertical blanking period of a
television signal for the object of copyright protection. Due to this
disturbing signal, when a software tape is illegally dubbed, then the
dubbed tape is recorded in a condition wherein the reproduced signal is
illegible. As a result, the copyright is protected.
On the other hand, in digital video tape recorders, an image compression
technique has made a remarkable development in recent years. It is a
common practice to decrease the overall amount of recording signals in
order to improve the picture quality. Therefore, such portions as a
vertical blanking portion are omitted, because they have no direct
relationship to the picture.
For example, in the case of the 525/60 system, 720 samples of data for an
effective scanning period shown in FIG. 39 are extracted with respect to
240 lines out of 23H to 262H in an odd-numbered field and 240 lines out of
285H to 524H in an even-numbered field. Similarly, in the case of the
625/50 system, 720 samples of data for an effective scanning period shown
in FIG. 39 are extracted with respect to 288 lines out of 23H to 310H in
an odd-numbered field and 288 lines of 335H to 622H in an even-numbered
field.
Image data obtained by extracting only actual image portions in this manner
are compressed to reduce the amount of data recorded. Thus recorded image
data are processed, upon reproduction, by reverse processes to those
performed upon recording.. Therefore, the vertical blanking portions and
horizontal blanking portions, which were deleted upon recording, are added
to the image data so that a composite video signal are outputted.
When it is tried to make a software tape for a digital video tape recorder
using such an image compression technique as described above, since only
actual image portions are recorded as described above, it is impossible to
insert a disturbing signal for a vertical blanking period, which is
recorded inserted in a software tape for use with an analog VTR for the
object of copyright protection.
The SCMS (Serial Copy Management System) which has been put into practical
use in the field of digital audio tapes is effective for the copyright
protection between digital video tape recorders. It cannot be anticipated
for digital video tape recorders the same kind of copyright protection
which is adopted in analog video tape recorders such as VHS video tape
recorders, most popularly spread at present.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a digital image signal
recording and/or reproduction method and apparatus of the data compression
type by which a disturbing signal can be recorded and played back. The
disturbing signal is inserted in a portion other than a portion where an
actual image of an image signal for the object of copyright protection
such as a disturbing signal employed by a software tape for an analog
video tape recorder.
It is another object of the present invention to provide a recording medium
on which a disturbing signal for the object of copyright protection is
recorded together with a digital image signal.
In order to attain the objects described above, according to an aspect of
the present invention, there is provided a method of recording a digital
image signal which has a recording format including a recording area for a
coded image signal and another recording area for incident information,
the recording area for incident information having a pack structure which
includes a header pack for recording line designation data designating an
arbitrary line of the image signal and a parameter regarding coding of the
recording signal and a data pack for recording data obtained by coding a
signal of a line designated by the header pack in accordance with the
parameter, the method comprising the steps of coding and recording the
image signal into the recording area for an image signal, recording data
designating a predetermined line of a copyright protection signal inserted
in the predetermined line of the image signal and a parameter regarding
coding of the copyright protection signal into the header pack, and
recording the coded copyright protection signal into the data pack.
According to a further aspect of the present invention, there is provided a
method of reproducing a digital image signal which has a recording format
including a recording area for a coded image signal and another recording
area for incident information, the recording area for incident information
having a pack structure which includes a header pack for recording line
designation data designating an arbitrary line of the image signal and a
parameter regarding coding of the recording signal and a data pack for
recording data obtained by coding a signal of a line designated by the
header pack in accordance with the parameter, the coded image signal being
recorded in the recording area for an image signal, data designating a
predetermined line of a copyright protection signal inserted in the
predetermined line of the image signal and a parameter regarding coding of
the copyright protection signal being recorded in the header pack, the
coded copyright protection signal being recorded in the data pack, the
method comprising the steps of reading the coded image signal from the
recording area for an image signal and decoding the read out, reading the
header pack and the data pack to restore the copyright protection signal,
and inserting the restored copyright protection signal into the
predetermined line of the decoded image signal.
According to a still further aspect of the present invention, there is
provided a recording medium on which a digital image signal is recorded,
the image signal having a recording format including a recording area for
a coded image signal and another recording area for incident information,
the recording area for incident information having a pack structure which
includes a header pack for recording line designation data designating an
arbitrary line of the image signal and a parameter regarding coding of the
recording signal and a data pack for recording data obtained by coding a
signal of a line designated by the header pack in accordance with the
parameter, the coded image signal being recorded in the recording area for
an image signal, data designating a predetermined line of a copyright
protection signal inserted in the predetermined line of the image signal
and a parameter regarding coding of the copyright protection signal being
recorded in the header pack, the coded copyright protection signal being
recorded in the data pack.
In accordance with the present invention, an image signal is coded and
recorded into the recording area for an image signal, and data designating
a predetermined line of a copyright protection signal inserted in the
predetermined line of the image signal and a parameter regarding coding of
the copyright protection signal are recorded into the header pack.
Further, the coded copyright protection signal is recorded into the data
pack.
On the other hand, the coded image signal is read from the recording area
for an image signal and decoded, and the header pack and the data pack are
read to restore the copyright protection signal. Then, the restored
copyright protection signal is inserted into the predetermined line of the
decoded image signal.
Thus, in accordance with the present invention, a copyright protection
signal inserted in a portion of a recording medium other than a portion
where an actual image of an image signal is recorded such as a disturbing
signal which is used by a software tape for use with an analog video tape
recorder can be recorded and/or reproduced by a digital video tape
recorder of the compression type.
The above and other objects, features and advantages of the present
invention will become apparent from the following description and the
appended claims, taken in conjunction with the accompanying drawings in
which like parts or elements are denoted by like reference characters.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagrammatic view showing a track of a digital video tape
recorder to which the present invention is applied;
FIG. 2 is a diagrammatic view showing a more detailed construction of an
ITI area of the digital video tape recorder of FIG. 1;
FIG. 3 is a diagrammatic view illustrating that the data structure on a
track is determined by an APT;
FIG. 4 is a diagrammatic view showing the structures of an application ID
on a tape and an application ID of an MIC;
FIGS. 5(a) and 5(b) are diagrammatic views showing the structure of data on
a track when APT=000;
FIG. 6 is a table showing the construction of pack data;
FIG. 7 is a diagrammatic view showing the hierarchy of a header;
FIG. 8 is a table showing an outline of a pack header table;
FIG. 9 is a diagrammatic view illustrating data of PC1 of a source control
pack of audio auxiliary data and video auxiliary data;
FIG. 10 is a diagrammatic view showing the construction of an audio sector;
FIGS. 11(a) and 11(b) are diagrammatic views showing a pre-SYNC block and a
post-SYNC block of the audio sector, respectively;
FIGS. 12(a) and 12(b) are diagrammatic views showing a SYNC block of the
audio sector and a framing format, respectively;
FIG. 13 is a table showing audio auxiliary data for 9 packs extracted and
described in the direction of a track;
FIG. 14 is a diagrammatic view showing the construction of a video sector;
FIG. 15 is a diagrammatic view showing a SYNC block of the video sector;
FIG. 16 is a diagrammatic view showing a framing format of the video
sector;
FIG. 17 is a diagrammatic view showing a SYNC block for exclusive use for
video auxiliary data;
FIG. 18 is a table illustrating video auxiliary data for 45 packs extracted
and described in the direction of a track;
FIGS. 19(a) and 19(b) are tables showing the construction of ID sections;
FIG. 20 is a diagrammatic view showing the construction of a sub code
sector;
FIG. 21 is a diagrammatic view showing a SYNC block of the sub code sector;
FIGS. 22(a) and 22(b) are tables showing ID sections of the sub code
sector;
FIG. 23 is a table showing a data section of the sub code sector;
FIG. 24 is a diagrammatic view showing the structure of data of the MIC;
FIG. 25 is a waveform diagram showing an example of a copyright protection
signal;
FIGS. 26(a) to 26(c) are time charts illustrating the relationship between
a sampling period and a sampling pulse signal;
FIG. 27 is a diagrammatic view illustrating the relationship between a
quantized copyright protection signal and a video signal;
FIGS. 28(a) and 28(b) are diagrammatic views showing a line header pack and
a line data pack, respectively;
FIG. 29 is a diagrammatic view showing an example of a quantized copyright
protection signal stored in a line header pack and a line data pack;
FIG. 30 is a table showing an example wherein the header pack and the data
pack of FIG. 29 are stored in an optional area for video auxiliary data;
FIG. 31 is a diagrammatic view illustrating an example of a form of use of
the present invention on the recording side and the reproduction side;
FIG. 32 is a block diagram showing an example of the construction of a
copyright protection signal detection circuit;
FIGS. 33(a) to 33(e) are time charts illustrating operation of the
copyright protection signal detection circuit of FIG. 32;
FIG. 34 is a block diagram showing an example of the construction of a line
data signal generator;
FIG. 35 is a block diagram showing an example of the construction of a
format converter;
FIG. 36 is a block diagram showing an example of the construction of part
of a reproduction system of a digital video tape recorder;
FIG. 37 is a block diagram showing an example of the construction of part
of the reproduction system of the digital video tape recorder;
FIG. 38 is a block diagram showing an example of the construction of a
copyright protection signal generation circuit; and
FIG. 39 is a waveform diagram illustrating an effective scanning period of
a digital video tape recorder.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
1. Characteristics of Digital Video Tape Recorder
1-1. Track Format
FIG. 1 illustrates a track of a digital video tape recorder to which the
present invention is applied. Referring to FIG. 1, recording on the
digital video tape recorder is performed in order of an ITI (Insert and
track information) area, an audio area, a video area and a sub code area
from the track entrance side. It is to be noted that reference characters
IBG1 to IBG3 in FIG. 1 denote each an inter-block gap. For a video signal
of the 525/60 system, one frame comprises ten such tracks, and for a video
signal of the 625/60 system, one frame comprises 12 such tracks.
1-2. ITI Area
The ITI (Insert and Track Information) area recorded on the track entrance
side is a timing block for allowing post recording (insertion by
overwriting) to be performed with certainty. In particular, the ITI area
is provided to allow accurate positioning of any area following the ITI
area when it is rewritten with video data or audio data by post recording.
Although details will be hereinafter described, the digital video tape
recorder is constructed such that it can be applied to other apparatus
than recording and/or reproduction apparatus for a digital image signal
and a digital audio signal by using an application ID. Since re-writing of
data in a particular area is essentially required with any application
apparatus, the ITI area on the track entrance side is provided without
exception.
A large number of SYNC blocks with a short SYNC length are written in the
ITI area, and SYNC numbers are applied to the SYNC blocks in order from
the track entrance side. When it is tried to perform post recording, if
any of the SYNC blocks of the ITI area is detected, then the current
position on the track can be discriminated accurately from the number
written therein. Then, an area for post recording is decided based on the
position. Generally, on the track entrance side, a head is not contacted
well and stably from the reason of the mechanical accuracy. Therefore, in
the ITI area, a large number of SYNC blocks with a shorter SYNC length are
written so as to raise the accuracy in detection.
The ITI area includes four portions as particularly seen in FIG. 2. The ITI
area first includes a preamble of 1,400 bits which are used to allow
run-in of a PLL (Phase-lock loop) for reading a digital signal. It
includes next an SSA (Start SYNC Block Area) for the function described
above. The SSA includes 61 SYNC blocks each constituted from 30 bits. The
SSA is followed by a TIA (Track Information Area). The TIA is constituted
from three blocks and hence from 90 bits. The TIA is an area for storing
information regarding the entire track. Each of the blocks in the TIA
stores a total of 6 bits including 3 bits for an APT (Application ID of a
track) which is an original application ID (details of which will be
hereinafter described), 1 bit for an SP/LP representative of a track
pitch, 1 bit for reservation, and 1 bit for a PF (Pilot Frame)
representative of a reference frame for a servo system. The ITI finally
includes 280 bits for a postamble for providing a margin.
1-3. Application ID System
The assignee of the present patent application has proposed a system called
application ID which allows easy development of such digital video tape
recorder to various other apparatus than recording and/or reproduction
apparatus for a digital image signal and a digital audio signal (refer to
U.S. patent application Ser. No. 08/159,455 filed on Nov. 30, 1993, U.S.
patent application Ser. No. 08/159,238 filed on Nov. 30, 1993, and U.S.
patent application Ser. No. 08/159,554 filed on Dec. 1, 1993).
Further, the assignee of the present patent application has proposed
another system wherein a circuit board with a memory IC mounted thereon is
carried in a cassette of a recording medium for a digital video tape
recorder. When the cassette is loaded into a digital video tape recorder,
data written in the memory IC are read out to assist recording and/or
reproduction (refer to U.S. patent application Ser. No. 08/067,285 filed
on Jun. 24, 1994 and U.S. patent application Ser. No. 08/142,813 filed on
Oct. 25, 1993). In the present specification, the system will be
hereinafter referred to as MIC (Memory In Cassette). The application ID
system and the MIC will be described subsequently to clarify the
characteristics of the digital video tape recorder to which the present
invention is applied.
An application ID is stored not only in the APT of the TIA area but also in
upper 3 bits at an address 0 as an APM (Application ID of MIC).
The application ID is not an ID which determines an example of application
of a digital video tape recorder but an ID which merely determines the
data structure of an area of a recording medium. Accordingly, the
following significances are provided.
APT . . . defines the structure of data on the track
APM . . . defines the structure of data of the MIC
The structure of data on the track is defined by the value of the APT. In
particular, the track following the ITI area is divided into several areas
as shown in FIG. 3. The data structure are determined decisively such as
the positions of the areas on the track, the construction of SYNC blocks,
the ECC construction for protecting data from an error and so forth.
Further, each of the areas includes an application ID which defines the
structure of data in the respective area. In other words, an application
ID of the area (n) defines the structure of data of the area (n).
The application IDs on a tape have such a hierarchy as shown in FIG. 4. In
particular, areas on the track are defined by the APT which is an original
application ID, and AP1 to APn are defined for the individual areas. The
number of areas is defined by the APT. While the application IDs are shown
in double levels in FIG. 4, a further level may be provided below them if
necessary. In contrast, the APM which is an application ID in the MIC is
provided in a single level. An equal value to that of the APT of an
application apparatus is written into the APT by a digital video tape
recorder.
By using this application ID system, without modifying its cassette,
mechanism, servo system or a detecting circuit of ITI area generation,
etc., a digital video tape recorder for a consumer can be applicable to
quite different categories of products such as, for example, data
streamers or multi-track digital audio tape recorders. Further, even if an
area is determined, since the contents thereof can be defined by the
application ID of the area, in such a manner that the contents are video
data when the application ID has a certain value, but the contents are
video/audio data or computer data when the application ID has another
value. It can be, therefore, developed to wide variety of products
categories.
A manner of the track when the APT=000 is illustrated in FIGS. 5(a) and
5(b). In this instance, areas 1, 2 and 3 are defined on the track. Then,
the positions of them on the track, the SYNC block construction, the ECC
construction for protection of data from an error, a gap for assuring each
adjacent areas and an overwrite margin for assuring overwriting are
determined. Further, each area includes an application ID which determines
the data structure of the area. In other words:
AP1 . . . determines the structure of data of the area 1;
AP2 . . . determines the structure of data of the area 2;
AP3 . . . determines the structure of data of the area 3.
Further, when the application IDs of the areas are all "000", they are
defined in the following manner:
when AP1="000" . . . an audio, AAUX data structure for a digital video tape
recorder for a consumer is adopted;
when AP2="000" . . . a video, VAUX data structure for a digital video tape
recorder for a consumer is adopted;
when AP3="000" . . . a sub code, ID data structure for a digital video tape
recorder for a consumer is adopted. The typical example is shown in FIG.
5(b).
Here, AAUX denotes Audio Auxiliary Data, and VAUX denotes Video Auxiliary
Data. When a digital video tape recorder for a consumer is realized, APT,
AP1, AP2, AP3, all become "000". Of course, the APM is "000".
When APT is "000", all areas for the AAUX, VAUX, sub codes and MIC are
described in a common pack structure. As shown in FIG. 6, one pack is
constituted from 5 bytes, and one byte (PC0) at the top represents a
header while the remaining 4 bytes (PC1 to PC4) represent data. The word
"pack" denotes a minimum unit of data, and related data are collected to
constitute a pack.
Eight bits of the header are divided into upper 4 bits and lower 4 bits and
have a hierarchy. The header is constructed in double levels from an upper
header of the upper 4 bits and a lower header of the lower 4 bits as shown
in FIG. 7. The hierarchy can be extended to a further lower level by bit
assignment of data. By such hierarchization, contents of the pack are
organized precisely, and extension of the same is easy. Further, 256
spaces by the upper header and the lower header are prepared as a single
pack header table together with contents of the packs. The areas mentioned
above are described using the pack header table.
FIG. 8 is a diagrammatic view showing an outline of the pack header table.
In the pack header table shown, the upper 4 bits are called large item
while the lower 4 bits are called small item. The large item of the upper
four bits is data representing, for example, an application of succeeding
data. Meanwhile, the lower 4 bits are data representing, for example,
detailed contents of succeeding data.
The large item can represent, as seen in FIG. 8, control by "0000", title
by "0001", chapter by "0010", part "0011", program by "0100", audio
auxiliary data by "0101", video auxiliary data by "0110", camera by
"0111", line by "1000", and soft mode by "1111".
Here, for the large item, for example, for the audio auxiliary data "0101"
and the video auxiliary data "0110", the small items are provided
representing recording signal source by "0000", source control by "0001",
recording date by "0010" and recording time by "0011".
FIG. 9 illustrates data of the PC1 of a source control pack of audio
auxiliary data and video auxiliary data. In the pack shown, SCMS data of 2
bits, copy source data of 2 bits, copy generation data of 2 bits, cipher
type data of 1 bit and cipher data of 1 bit are recorded in order from the
MSB side.
With the large item for the line "1000", the small items are provided
representing line header by "0000", Y by "0001", R-Y by "0010", B-Y by
"0011", R by "0101", G by "0110" and B by "0111". In other words, sampling
data of any line within a vertical blanking period or an effective
scanning period of a television signal, or sample data of an image signal
other than a television signal can be recorded with the large item for the
line "1000".
It is to be noted that the large items represented by "1001" to "1110" are
each left for later addition of a large item. Accordingly, recording of
any new data will be allowed in future by defining a new header using the
code of item data which are not yet defined (for example, one of the large
items of "1001" to "1110" for future addition).
While the pack structure basically has a fixed length of 5 bytes, as a
single exception, a pack structure of a variable length is used only for
description of character data into the MIC. This is intended to make an
effective use of the limited memory capacity.
1-4. Audio Sector
The audio and video areas are called audio sector and video sector,
respectively. FIG. 10 illustrates the construction of the audio sector.
The preamble is constituted from 500 bits and includes a run-up of 400
bits and two pre-SYNC blocks. The run-up is used as a run-up pattern for
pulling into a PLL. The pre-SYNC block is used for detection of an audio
SYNC block in advance. The postamble at the end is constituted from 550
bits and includes a post-SYNC block and a guard area of 500 bits. The
post-SYNC is provided to confirm an end of the audio sector by means of
the SYNC number of ID thereof. The guard area is provided to guard so that
post recording of the succeeding video sector may not invade the audio
sector.
Each of the pre-SYNC and post-SYNC blocks is constituted from 6 bytes as
seen from FIG. 11(a) and 11(b). The sixth byte of each pre-SYNC block has
a discrimination byte between the SP/LP. The SP is represented by FFh
whereas the LP is represented by OOh. The sixth byte of the post-SYNC
block has FFh stored therein as dummy data.
The discrimination byte for the SP/LP is present as an SP/LP flag also in
the TIA area described above, but here, it is present for protection of
the SP/LP flag. If the value in the TIA area can be read, then it is
adopted, but if the value cannot be read, then the value of the SP/LP
discrimination byte area is adopted.
Since 6 bytes of each of the pre-SYNC and post-SYNC blocks is recorded
after it is converted by 24-25 conversion (modulation method wherein data
of 24 bits are converted into data of 25 bits), pre-SYNC blocks have a
total bit length of 6.times.2.times.8.times.25.div.24=100 bits and the
post-SYNC block has a total bit length of
6.times.1.times.8.times.25.div.24=50 bits.
Each one SYNC block of the audio SYNC blocks is constituted from 90 bytes
as seen from FIG. 12(a). The first 5 bytes of the front end have a similar
construction to that of the pre-SYNC blocks or the post-SYNC block. The
data section is constituted from 77 bytes and is protected by a horizontal
parity C1 (8 bytes) and a vertical parity C2 (77 bytes.times.5).
Fourteen audio SYNC blocks are provided per one track. Since data of the
audio SYNC blocks are recorded after processing by 24-25 conversion, the
total bit length thereof is 90.times.14.times.8.times.25.div.24=10,500
bits.
The second 5 bytes at the front end of data section are provided for audio
auxiliary data. They constitute one pack. A total of 9 packs are prepared
for one track. The numbers from 0 to 8 in FIG. 12(a) represent pack
numbers in the track.
FIG. 13 is a diagrammatic view showing audio auxiliary data of nine packs
extracted and described in a track direction. Here, the numbers from 50 to
55 indicate the values (in hexadecimal notation) of pack headers. The same
packs are each written 10 times onto 10 tracks. This portion is called
main area. Since essential items such as a sampling frequency and a
quantization bit number necessary for reproduction of an audio signal are
mainly stored here, they are repeatedly written for protection of the
data. Consequently, data in the main area can be reproduced irrespective
of a lateral scratch or a one-channel clog or the like which is likely
caused by tape transportation.
The remaining packs are all linked in an order and used as an optional
area. Packs in the main area are linked, skipping like a, b, c, d, e, f,
g, h, . . . , in the direction indicated by an arrow mark in FIG. 13.
Within one video frame, 30 packs (525/60 system) or 36 packs (625/50
system) are prepared as the optional area. Here, since the optional area
literally means an option, it may be selected freely from the pack header
table of FIG. 8, respectively for each digital video tape recorder.
The optional area may be constituted from a common option (for example,
character data) and a maker's option which is not common, whose contents
are predetermined uniquely by a manufacturer's choice. Since the common
option and the maker's option are options, only one or both or none of
them may be provided. Where no information is present, this is described
using a pack "NO INFO pack" representing absence of information. The areas
for the application IDs and for the options are divided by appearance of a
maker code pack. The area following the maker code pack is a maker's
optional area.
The mechanism of the main area, the optional area, the common option and
the maker's option is all common to the audio auxiliary data, the video
auxiliary data, the sub codes and the MIC.
1-5. Video Sector
FIG. 14 shows the construction of the video sector. The constructions of
the preamble and the postamble are same as those of the audio sector of
FIG. 10. The amount of the guard area of the postamble is greater than
that of the audio sector.
Each of the video SYNC blocks is constituted from 90 bytes similarly to the
audio SYNC blocks as seen from FIG. 15. The first 5 bytes at the front end
have a similar construction to that of the pre-SYNC, post SYNC and audio
SYNC blocks. The data section is constituted from 77 bytes and is
protected by a horizontal parity C1 (8 bytes) and a vertical parity C2 (77
bytes.times.11) as seen in FIG. 16. Two SYNC blocks (.alpha. and .beta.)
at an upper portion in FIG. 16 and one SYNC block (.gamma.) just prior to
the C2 parity are SYNC blocks for exclusive use for the VAUX, and the
respective data of 77 bytes are used as video auxiliary data. In the video
SYNC blocks other than the SYNC blocks for exclusive use for the VAUX and
the C2 parity SYNC block, video data of a video signal are stored, being
compressed by DCT (Discrete Cosine Transform).
In FIG. 16, the central 135 SYNC blocks make a storage area for video data.
While numbers from BUF0 to BUF26 appear in FIG. 16, BUF denotes one
buffering block. One buffering block is constituted from 5 SYNC blocks and
one track is constituted from 27 buffering blocks, and consequently, one
video frame which is constituted from 10 tracks is constituted from 270
buffering blocks.
An area effective for an image are extracted out of image data of one frame
and the thus sampled digital data are shuffled and collected from various
portions of an actual image to make up a group of 270 data. Such one group
makes one buffering unit. The data are compressed for each unit using a
compression technique which employs the DCT method or the like. This
processing is performed while evaluating whether or not the entire data
remain within a desired compression value. Thereafter, the compressed data
of one buffering unit are packed into one buffering block and 5 SYNC
blocks.
FIG. 17 illustrates the construction of SYNC blocks for exclusive use for
the VAUX. Two SYNC blocks (.alpha.) and (.beta.) at an upper portion of
FIG. 16 corresponds to the two SYNC blocks (.alpha.) and (.beta.) at an
upper portion of FIG. 17, and one SYNC block (.gamma.) just prior to C2 in
FIG. 16 corresponds to the lowermost SYNC block (.gamma.) in FIG. 17. If
the 77 bytes are divided by a unit of a pack of 5 bytes, then 2 bytes
remain, and such remaining two bytes are reserved and not used
particularly. If the packs are numbered similarly to the packs of audio
data, then a total of 45 packs from 0 to 44 are assured for one track.
FIG. 18 shows video auxiliary data for 45 packs extracted and described in
a track direction. Here, the numbers from 60 | | |
