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Claims  |
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What is claimed is:
1. A method for copy protecting television broadcast program signals
transmitted by a broadcasting system and received by a video recorder,
said video recorder recording said television broadcast program signals as
digital signals in a format, reserving areas for accessory information
relating to said format, and reserving other areas for digital image
signals, said method comprising steps of:
receiving transmitted signals;
determining whether the received signals are the television broadcast
program signals transmitted by said broadcasting system;
detecting a generation limiting signal and determining whether said
generation limiting signal indicates a copy once state for allowing the
television broadcast program signals to be copied once;
changing a record generation limiting signal to be recorded in said
recording areas reserved for said accessory information from the copy once
state represented by said generation limiting signal allowing the received
signals, once recorded, to be copied, to a copy protect state which
inhibits copying of said received signals when said received signals are
determined to be said television broadcast program signals;
inserting said generation limiting signal in said areas reserved for said
accessory information in those digital signals determined to be the
television broadcast program signals; and
recording to said video recorder said received television broadcast program
signals including said generation limiting signal,
wherein when said generation limiting signal is not detected at said
detecting step, said inserting step inserts a record generation limiting
signal indicating said copy once state in said areas reserved for said
accessory information in those digital signals determined to be television
broadcast program signals, and
wherein said television broadcast program signals includes AAUX/VAUX source
control packs for respective audio and video source control information;
and further comprising the step of retrieving from an AAUX/VAUX source
control pack copy generation limiting signals (CGMS) as said generation
limiting signal.
2. A video recorder for copy protecting television broadcast program
signals transmitted by a broadcasting system and received by said video
recorder, said video recorder being operable to digitally record said
television broadcast program signals in a format, reserving recording
areas for accessory information relating to said formal, and reserving
other recording areas for digital image signals, said video recorder
comprising:
means for receiving transmitted signals as input signals;
means for coding said input signals for recording in accordance with said
format and for recording the coded input signals in said reserved other
recording areas;
means for recording, in said recording areas reserved for said accessory
information, a record generation limiting signal for copy protecting said
input signals to be recorded in said other recording areas;
means for determining whether said input signals are television broadcast
program signals transmitted by said broadcasting system;
means for detecting a generation limiting signal and determining whether
said generation limiting signal indicates a copy once state for allowing
the television broadcast program signals to be copied once;
means for changing said record generation limiting signal to be recorded in
said recording areas reserved for said accessory information from a copy
allow state allowing the input signals, once recorded, to be copied, to a
copy protect state for copy protecting said input signals to prevent said
input signals, once recorded, to be copied, when said means for
determining determines said input signals are television broadcast program
signals; and
means for setting said record generation limiting signal to a copy once
state allowing the input signals, once recorded, to be copied once, in
said recording areas reserved for said accessory information when said
input signals are determined to be the television broadcast program
signals and said generation limiting signal is not detected by said
detecting means,
wherein said television broadcast program signals includes AAUX/VAUX source
control packs for respective audio and video source control information;
and further comprising means for retrieving from an AAUX/VAUX source
control pack copy generation limiting signals (CGMS) as said generation
limiting signal.
3. A video recorder/reproducer for copy protecting television broadcast
program signals transmitted by a broadcasting system and received by said
video recorder/reproducer, said video recorder/reproducer being operable
to digitally record said television broadcast program signals in a video
recorder format reserving recording areas for accessory information
relating to said format and reserving other recording areas for digital
image signals, said video recorder/reproducer being further operable to
reproduce those signals which have been recorded in said format, said
video recorder/reproducer comprising:
means for receiving transmitted signals as input signals;
means for coding said input signals for recording in accordance with said
format and for recording the coded input signals in said reserved other
recording areas;
means for detecting a generation limiting signal and determining whether
said generation limiting signal indicates a copy once state for allowing
the television broadcast program signals to be copied once;
means for recording, in said recording areas reserved for said accessory
information, said generation limiting signal for copy protecting said
input signals to be recorded in said other recording areas;
means for determining whether said input signals are television broadcast
program signals transmitted by said broadcast system;
means for changing said generation limiting signal to be recorded in said
recording areas reserved for said accessory information from a copy allow
state allowing the input signals, once recorded, to be copied, to a copy
protect state for copy protecting said input signals to prevent said input
signals, once recorded, to be copied, when said means for determining
determines said input signals are television broadcast program signals;
means for inserting a record generation limiting signal indicating a copy
once state allowing the input signals, once recorded, to be copied once,
in said recording areas reserved for said accessory information when said
input signals are determined to be the television broadcast program
signals and said generation limiting signal is not detected by said
detecting means;
means for reproducing the recorded input signals and the recorded accessory
information, including said generation limiting signal; and
means for inserting said generation limiting signal into television signals
derived from the reproduced signals when said generation limiting signal
reproduced from said recording areas reserved for said accessory
information is set to the copy protect state, and for changing said
reproduced generation limiting signal from the copy allow state allowing
copying to the copy protect state for preventing copying and inserting the
changed generation limiting signal into said derived television signals,
when said reproduced generation limiting signal indicates copy protection
of the reproduced input signals,
wherein said television broadcast program signals includes AAUX/VAUX source
control packs for respective audio and video source control information;
and further comprising means for retrieving from an AAUX/VAUX source
control pack copy generation limiting signals (CGMS) as said generation
limiting signal.
4. A video reproducer for reproducing copy protected television broadcast
program signals which include said television broadcast program signals
having been digitally transmitted from a television broadcasting station,
received and recorded as digital video signals in respective video areas
of a record medium and related accessory information in other areas
reserved therefore, with said accessory information including generation
limiting data derived from a generation limiting signal included in said
television broadcast program signals, comprising:
means for reproducing said digital video signals and said generation
limiting data from said record medium;
means responsive to the reproduced generation limiting data for generating
and inserting generation limiting signals into television signals derived
from the reproduced digital video signals when said reproduced generation
limiting data is set to a copy protecting state;
means for changing the reproduced generation limiting data from a copy
allow state allowing copying to the copy protecting state that prevents
copying; and
means for generating and inserting a changed generation limiting signal
into said derived television signals when said reproduced generation
limiting data indicates copy protection of the reproduced digital video
signals, wherein said generation limiting data indicating a copy once
state allowing the input signals, once recorded, to be copied once, is
recorded in said other reserved areas when said input signals are
determined to be the television broadcast program signals and the
generation limiting signal therefor is not detected,
wherein said television broadcast program signals includes AAUX/VAUX source
control packs for respective audio and video source control information
and further comprising means for retrieving from an AAUX/VAUX source
control pack copy generation limiting signals (CGMS) as said generation
limiting data. |
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Claims |
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Description |
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BACKGROUND OF THE INVENTION
The present invention relates to recording and reproducing a digital
picture signal and, more particularly, to copy protecting television
broadcast programs recorded and reproduced as a digital picture signal.
Television broadcast programs are recorded and played back by a viewer
using a video tape recorder (VTR). The VTR may be an analog VTR, but
analog technology cannot record a TV program with high image quality and,
as a result, the reproduced analog TV broadcast program has a lower image
quality than the originally broadcast TV program.
A commercially available digital VTR, on the other hand, offers high image
recording quality. With the digital VTR, therefore, the reproduced TV
program has virtually the same image quality as the originally broadcast
TV program.
Copyright protection of video programs on video tape is available in both
analog and digital VTRs. In the analog VTR, a copyright protection signal
is inserted into the blanking interval of the pre-recorded analog video
signal. The copyright protection signal prevents the analog VTR from
copying a copyright protected analog video program from a commercially
available analog video tape. The digital VTR provides a Serial Copy
Management System (SCMS) to copyright protect a digital video program on a
digital video tape. A form of the SCMS copyright protection system has
been used to prevent copying of audio data recorded on a Digital Audio
Tapes (DAT). The SCMS technique restricts copying, but is limited to copy
protecting output digital signals and is ineffective if those digital
signals are converted to analog form.
Problematically, the above-described copy protection techniques can be
circumvented. If a digital VTR inserts a copyright protection code into
the digital video data to prevent another digital VTR from copying the
digital video program, the conversion of the digital video program to
analog form could defeat such protection. An analog VTR does not recognize
the digitally recorded copyright protection signal. By obtaining the
analog video program from analog output terminals of the digital VTR,
therefore, the above copyright protection schemes are circumvented. Worse,
since the unauthorized copy is made from the high image quality
reproduction of the digital VTR, an unauthorized high image quality copy
is produced.
A technique for protecting a copyrighted program for use in a digital VTR
has been described in Japanese Patent Applications Nos. 5-277633 and
6-82576. According to the proposed technique, a video signal is recorded
with a copyright protection signal inserted into a line of the video
signal together with data that specifies which line contains the
protection signal. A parameter for coding the copyright protection signal
is recorded in a data pack. However, the proposed technique does not
copyright protect TV broadcast signals.
OBJECTS AND SUMMARY OF THE INVENTION
It is, therefore, an object of the invention to provide copyright
protection of a TV broadcast program.
It is a further object of the invention to provide copyright protection of
a TV broadcast program recorded by a digital VTR which is effective even
if the digitally recorded program is reproduced by another digital VTR or
by an analog VTR coupled thereto through a digital interface or by a
digital VTR having an analog video output.
In accordance with the above objectives, a copy protection method and
apparatus are provided for copy protecting a television broadcast program
that is to be recorded in a digital format that reserves recording areas
for accessory information concerning the structure of the tape format and
for the input image signal. When the input signal is determined to be a
television broadcast program, a generation limiting signal is set to a
copy protect state and inserted into the received signal for recording
therewith. Preferably, this generation limiting signal is recorded in a
pack with the accessory information. If the digitally recorded television
signal is reproduced and supplied as an output analog signal, the
generation limiting signal is used to insert a copy protect signal into
the analog output.
BRIEF DESCRIPTION OF THE DRAWINGS
The above objects, features and advantages of the present invention will
become apparent from the following detailed description of illustrative
embodiments which is to be considered in connection with the accompanying
drawings, in which:
FIG. 1 is a diagram of the tape format of one track in a digital VTR to
which the present invention applies;
FIG. 2 is a diagram showing a structure of the ITI area shown in FIG. 1;
FIG. 3 is a diagram showing the data structure of a track defined by an
application ID (APT);
FIG. 4 is a diagram showing the application ID (APT) structure;
FIGS. 5A and 5B are diagrams showing data structures on a track when
APT=000;
FIG. 6 is a diagram showing the structure of pack data;
FIG. 7 is a diagram showing an hierarchical structure of a header;
FIG. 8 is a table showing the summary of a pack header;
FIG. 9 is a diagram showing the PC1 data structure of a source control
pack;
FIG. 10 is a diagram showing the structure of an audio sector;
FIGS. 11A and 11B are diagrams showing the pre-SYNC and post-SYNC bytes of
an audio sector;
FIGS. 12A and 12B are diagrams showing a SYNC block and a framing format of
the audio sector;
FIG. 13 is a table for describing 9 packs of the audio data along a track;
FIG. 14 is a diagram showing the content of an AAUX SOURCE CONTROL pack;
FIG. 15 is a diagram showing the definition of a VAUX SOURCE CONTROL pack;
FIG. 16 is a diagram showing the structure of VBID with a 2-bit CGMS;
FIGS. 17A and 17B are graphs showing a VITS signal;
FIG. 18 is a diagram showing the VITS signal;
FIG. 19 is a flowchart implementing an embodiment of the present invention;
FIG. 20 is a block diagram of a recording circuit including the present
invention;
FIG. 21 is a block diagram of a VAUX recording circuit included in the
recording circuit of FIG. 20;
FIGS. 22A and 22B are diagrams showing main and optional areas for VAUX
data;
FIG. 23 is a block diagram showing a VAUX pack data generator;
FIG. 24 is a diagram showing the data content for the main area of the VAUX
pack data;
FIG. 25 is a block diagram showing an AAUX pack data generator;
FIG. 26 is a diagram showing the data content for the main area of the AAUX
pack data;
FIG. 27 is a block diagram of a MIC microcomputer;
FIG. 28 is a block diagram of a TV signal determining circuit;
FIG. 29 is a block diagram of a portion of a reproducing circuit which
incorporates the present invention;
FIG. 30 is a block diagram of another portion of the reproducing circuit
intended to be coupled to FIG. 29;
FIG. 31 is a block diagram of a VAUX detector provided in the reproducing
circuit;
FIG. 32 is a block diagram of a VAUX reproducing circuit intended to be
coupled to FIG. 31; and
FIG. 33 is a block diagram of a digital copying circuit.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to the drawings, wherein like reference numerals designate
identical or corresponding parts throughout the several views, the present
invention will now be described.
Tape Format
Before describing the present invention, reference is made to the format in
which digital video signals are recorded on tape. The digital VTR records
tracks using a helical recording technique, wherein a rotary magnetic head
spins at an angle to the video tape which travels along a head scan
direction. The resulting track pattern has tracks arranged at a slant
along the tape medium (not shown). An example of the format for a track is
shown in FIG. 1, wherein the track begins and ends with margins (1250
bits) that define the data area. Insert and Track Information (ITI) is
provided at the beginning of each track and includes timing information
representing the position of the audio, video and subcode areas within the
track. Inter-Block Gaps (IBG1, IBG2, IBG3) segregate the audio, video and
subcode areas of the track. An audio area of 10500 bits provides for audio
data storage followed by a video area of 111,750 bits for video data
storage, and, then, by a subcode area of 1200 bits for the subcode area.
Pre-ambles and post-ambles bound the audio, video and subcode areas. For a
525 line/50 Hz VTR system, 10 such tracks are used to record a single
video frame (including audio data) of an audio/video program, which 12
tracks accommodate a 625 line/60 Hz system.
The ITI is a header of the track and includes information for aligning the
audio, video and subcode data within that track for after recording
operations. As shown in FIG. 2, the ITI area begins with a preamble which
is comprised of 1400 bits used as a run-in for the magnetic head of the
VTR. The preamble is followed by a Start Sync Block Area (SSA) comprised
of 1830 bits with 61 sync blocks (30 bits apiece) therein. These sync
blocks contain synchronizing information which is useful for timing the
audio, video and subcode areas of each track. When audio copying or
re-recording is performed, for example, the sync block containing the
timing information for the audio area is detected from the SSA and the
position of the desired audio area can be determined therefrom.
It will be appreciated that it is; difficult to keep the magnetic head of
the VTR in contact with the inlet side of each track because of mechanical
limitations, making scanning of the inlet side of each track unstable.
This is true for the ITI area which is placed near the inlet of each
track. To enhance the sensing probability of the sync blocks, the length
of the sync blocks is shortened and the number of sync blocks is
increased.
Following the SSA are 90 bits of a Track Information Area (TIA) formed of
three blocks which, as will be explained in more detail, store information
about the track. Each block includes an Application ID of a Track (APT)
(three bits) including an SP/LP bit which indicates track pitch; a reserve
bit; and a Pilot Frame (PF) bit which represents a reference for the servo
system. The TIA is followed by the postamble composed of 280 bits which is
used to provide a margin for the ITI area.
The track in FIG. 1 includes audio, video and subcode areas; but each track
may contain n data areas such as shown in FIG. 3. The ITI indicates where
these areas begin/end and the digital VTR employs the ITI to quickly find
and retrieve the desired area (AREA1, AREA2, AREA3). An application ID may
be provided for each area.
The application ID (APT) stored in the TIA designates the different areas
as being video, audio or sub-code areas. The application ID (APT)
preferably is arranged as an hierarchy of application IDs as shown in FIG.
4. With such an hierarchical structure, whole branches of data including
several areas of the hierarchical "tree" can be extracted by the digital
VTR. Thus, newly defined data areas may be accommodated by this
hierarchical structure.
In addition to storing this hierarchical structure in the TIA of the tape,
an hierarchy may be stored in a memory IC (MIC) of the tape cassette that
is used with the digital VTR. The MIC can be employed to store information
relating to all of the recorded programs on the video tape to assist the
VTR in recording and reproducing the data from a newly loaded record
medium. For example, the MIC can be used to mark a predetermined program,
designate the reproduction order of programs, designate a predetermined
scene for reproducing a still image (i.e., a photo), reserve a timer
record operation, etc.
The application ID of the MIC (APM) is shown in FIG. 4 and may occupy the
high order 3 bits of adrress 0. In a similar manner to the hierarchical
structure of Application ID of the tracks (APT), the APM determines the
data structure of the MIC. Japanese Patent Applications 5-277633 and
6-82576 describe an MIC which may be used for this purpose.
It will be appreciated that the application ID is not an ID for defining an
application of the digital VTR, but is an ID for defining the data
structure of an area of the record medium. That is, the application ID
(APT) stored in the TIA defines the data structure on the track, and the
application ID (APM) of the MIC defines the data structure of the MIC.
As an example of the application ID (APT) defining the data structure of
different areas of the track, reference will be made to FIGS. 5A and 5B.
When the application ID (APT) is set=000, the track is arranged as shown
in FIG. 5A with three areas (AREA1, AREA2 and AREA3). The application IDs
(AP1, AP2, AP3) are stored in each respective area and contain information
on the arrangement of the data within the respective area. For example,
when the information in the AP1 is set=000, the data structure of AREA1 is
an audio data structure which includes Audio Accessory Data (AAUX); when
the information in AP2 is set=000, the data of AREA2 is video data which
includes Video Accessory Data (VAUX); and, when AP3 is set=000, the data
of AREA3 is subcode data. It will be appreciated that configuring the
application ID for the three areas AP1, AP2 and AP3=000 corresponds to a
configuration for commercial use. Thus, the three areas (AREA1, AREA2,
AREA3) shown in FIG. 5A are designated as audio, video and subcode areas,
respectively, as shown in FIG. 5B. Of course, any digital representation
for an application ID can be used to indicate the data structure. Also,
the application ID (APM) may be of a similar structure.
With the specific format set by the application ID (APT), the digital VTR
records the different data (audio, video, subcode) onto the record medium.
The actual AAUX, VAUX and subcode data are recorded in the areas (AREA1,
AREA2, AREA3) as a plurality of structures called packs having the common
pack structure shown in FIG. 6. As shown, a pack is composed of 5 bytes
(PC0 . . . PC4) with the high order byte reserved as a header (PCO) and
the 4 lower bytes reserved for data.
The header is divided into the hierarchical structure shown in FIG. 7. The
high order or upper 4 bits of the header (PCO), for example, serve as an
upper header and the lower order 4 bits of the header serves as a lower
header in the hierarchical structure shown in FIG. 7. The hierarchy can be
expanded to further lower levels by using the bits in the lower header.
With this arrangement, it is possible to clearly systemize the content of
each pack and easily expand the packs. When the pack header is represented
by a table, for example, the 8 bits of the pack header can represent 256
different pack structures.
FIG. 8 shows such a pack header table for tabulating pack header codes that
define the structure of the corresponding pack. The upper four bits of the
pack header table constitute what is called a large item and the lower
four bits constitute what is called a small item. The large item indicates
the manner in which the small item, containing the information about the
pack structure, is to be applied. FIG. 8 shows the large item set to
"0000" for providing control; a large item of "0001" indicates the title;
a large item of "0010" indicates a chapter; a large item of "0011"
indicates a part; a large item of "0100" indicates a program; a large item
of "0101" indicates AAUX data; a large item of "0110" indicates VAUX; a
large item of "0111" indicates a camera; a large item of "1000" indicates
a line; and a large item of "1111" indicates a soft mode. Large items
"0101" indicating AAUX data and "0110" indicating VAUX data provide small
items such as a source control "0001", a recording signal source "0000", a
recording date "0010" and a recording time "0011".
The large item "1000" provides small items for providing information for a
recording operation of a line of the vertical blanking period or the
effective scan period of a TV signal, such as data sampled from a video
signal. The small item information for the line "1000" provides
information for recording the video line such as, for example, a line
header "0000", a luminance (Y) "0001", color difference "0010" (R-Y),
"0011" (B-Y), red (R) "0101", green (G) "0110", and blue (B) "0111".
It will be noted that large items "1001" to "1110" in FIG. 8 are reserved
for additional data. Items which are undefined, for example, may be coded
as the reserved large items, thus defining new definitions for optionally
recording new data in the future.
An example of the source control pack for either the AUUX or VAUX indicated
by the source control large item "0000" is shown in FIG. 9 as data area
PC1 of the pack of FIG. 6. Serial Copy Management System (SCMS) data is
stored in the first two bits of PC1 which determine the copy protection of
the recorded video program; copy source data is stored in the next two
bits which determine the source of the data to be copied; copy generation
data is stored in the following two bits; cipher type is stored in the
next bit; and cipher data is stored in the least: significant bit (LSB).
As shown in FIG. 13, packs are arranged within a track in a grid with, for
example, each of the packs (0 . . . 8) corresponding to an AAUX pack. Each
data pack is fixed in length to 5 bytes. However, when data is written to
the MIC, the pack structure has a variable length such that the MIC can be
filled to capacity to obtain the most efficient use of the MIC.
The audio data is stored in an audio sector on the record medium in the
arrangement shown in FIG. 10 including a preamble, an audio area and a
postamble. The video data is stored in an analogous video sector. The
preamble includes a run-up of 400 bits for synchronizing a PLL followed by
100 bits of pre-sync information used for pre-detection of the audio sync
blocks in the audio area. The audio area stores the audio data and is
composed of 14 audio sync blocks (10,500 bits). The postamble includes 50
bits of a post-sync block used to definitively mark the end of the audio
sector followed by 500 bits of a guard area to prevent after-recorded
audio data from overlapping into the next video sector.
The pre-sync and the post-sync blocks are shown in more detail in FIGS. 11A
and 11B, respectively. The pre-sync block is shown as having 6 bytes,
including an SP/LP byte, which indicates a standard-play (SP) or a
long-play (LP) mode. Notably, the SP/LP byte is omitted from the post-sync
block of FIG. 1B. When the SP/LP block is set=FFh, for example, the SP
mode is indicated; and, when the SP/LP is set=00h, the LP mode is
indicated. It will be appreciated that the SP/LP byte is stored as an
SP/LP flag in the TIA area of the ITI and is stored in the pre-sync block
as a back-up in case the TIA area cannot be read. The remainder of the
pre-sync and post-sync blocks contain two sync bytes, followed by three
identification bytes (ID0, ID1 and IDP).
The bit lengths for the pre-sync and post-sync blocks are calculated as
follows. The pre-sync block has 6 bytes (FIG. 11A) with 8 bits in each
byte making a total of 48 bits. The pre-sync block is converted from
24-bit data into 25-bit data by a 24 to 25 conversion, thus a 25/24
conversion factor factoring 48 bits=50 pre-sync bits. There are two
pre-sync blocks, resulting in 6.times.2.times.8.times.25.div.28=100 bits.
There is only one post-sync block having the same overall structure
resulting in 6.times.1.times.8.times.25.div.24=50 bits.
The audio sync blocks are collected and recorded on the record medium in
the audio area (FIG. 5B) in groups of 14 sync blocks per track as shown in
FIG. 12A. The first nine audio sync blocks (0 . . . 8) contain the audio
data, whereas the last five sync blocks are reserved for parity
information. Five bytes of each audio sync block are reserved for the AAUX
pack, two bytes of the sync block are reserved for sync bytes, and three
bytes of the sync block are reserved for ID bytes, all as shown in FIGS.
12A and 12B. Recalling that the digital VTR performs a "24 to 25"
conversion prior to the recording of the digital signal, the total bit
length of the group of 14 sync blocks per track is 90 bytes per audio sync
block (FIG. 12B).times.14 audio sync blocks.times.8 bits per
byte.times.25/24 conversion factor=10,500 bits.
The audio area of FIG. 12A preferably includes the parity sectors C1 and
C2. The parity sector C1 occupying the last 8 bytes of each audio sync
block is known as horizontal parity because C1 assists the digital VTR in
detecting areas in the data of the respective audio sync blocks. The
parity sector C2 occupying the last 5 audio sync block positions of FIG.
12A, on the other hand, is known as a vertical parity because C2 assists
the digital VTR to determine what will be seen as vertical errors in all
the sync blocks.
The digital VTR records the AAUX data as data packs onto the record medium
in the manner shown in FIG. 13. Each of the pack numbers (0 . . . 8) in
FIG. 13 represents the AAUX packs (0 . . . 8) in FIG. 12A, and packs (0 .
. . 8) are comprised of pack headers 50 to 55 (hexadecimal) and optional
packs (a . . . g). It will be appreciated that AAUX packs, such as shown
in FIG. 12A, are written ten times over ten tracks to ensure that the
information in each data pack is recovered during a reproducing operation
even if a portion of the data is lost due to a mechanical failure. By
writing the pack data repeatedly over ten tracks, recovery of the AAUX
data is ensured even if a portion of the record medium is corrupted.
The optional packs are also written ten times. However, the number of total
optional packs changes with the video system. In the 525/60 VTR system of
FIG. 13, for example, 30 optional packs are recorded in a video frame and,
therefore, three optional packs are recorded in each track over ten
tracks. On the other hand, in a 625/60 VTR system, 36 optional packs are
recorded. It will be appreciated that the optional packs are truly
optional and may, or may not, be selected among the types of data shown by
the pack header table in FIG. 8.
In Japanese Patent Application 6-19991, a method for packing data retrieved
from the vertical blanking interval (VBID) is described. There, the packed
data is restored in the vertical blanking interval during playback; and
during recording the picture data is recorded but the vertical blanking
interval is discarded.
The main area data blocks (50 . . . 55) store essential information about
the audio data, such as a sampling frequency for reconstructing the audio
signal and the number of quantizing bits in each sample, for example.
Normally, these packs are linked in sequence, but may also be linked in
another order. In FIG. 13, for example, the audio packs are linked in the
direction of the arrows forming the sequence (a, b, c, 50, 51, 52, 53, 54,
55). Japanese Patent Application 6-19991 describes restoring the VBID data
from the packs indicated by pack headers 61h and 51h of the main area data
packs.
An example of a data pack configured as an AUUX pack is shown in FIG. 14.
The pack header (PCO) includes a large item "0101" indicating an AAUX pack
according to the pack header table (FIG. 8). Byte PC1 includes copy
generation information including two bits of SCMS code (FIG. 9)
incorporating copy generation limiting signals (CGMS). The individual bits
of the SCMS code represent the CGMS information shown in FIG. 9 and
indicate whether the corresponding audio data is copyrighted. The two-bit
combination of the SCMS bits represents SCMS information for managing the
CGMS information. The specific designations shown in FIG. 9 are reproduced
here for convenience.
Upper CGMS bit; 0 = not copyrighted
1 = copyrighted
Lower CGMS bit; 0 = original
1 = not original
SCMS Combination; 00 = freely copied
01 = not used
10 = one copy allowed
11 = copying prohibited
For example, the CGMS bits "10" read from an AAUX pack indicate that one
copy of the copyrighted, original audio track is allowed. Then, the CGMS
data is rewritten in the pack PC1 to "11" to prohibit further copying. The
AAUX pack of FIG. 14 includes in byte PC4 a record inhibit (RI) bit to
inhibit or allow copying of the corresponding audio data.
The video data is stored in sync blocks of a video region in a similar
fashion to the audio region shown in FIG. 10 Similar to the audio region,
the video region includes a preamble, a video area and a postamble. Since
video data is more comprehensive than audio data, however, more video sync
blocks (i.e., bytes per video sync block) are used by the video region
than by the audio region. Specifically, the video area is formed of
111,750 bits (versus 10,500 bits of the audio area) and the video guard
area is formed of 925 bits (versus 500 bits of the audio guard area). The
guard area of the video data is larger than in the audio data because
video data tends to be larger than audio data and more guard bits are
preferred to ensure that the video data does not overlap into adjoining
areas of the record medium. The video sync blocks of the video sector may
also include the parity portions C1 and C2, similar to that shown in FIG.
12A.
A data pack configured as a VAUX source control pack, for example, is shown
in FIG. 15. Similar to the AAUX source control pack of FIG. 14, the VAUX
source control pack includes a pack header with a large item "0110"
indicating VAUX data; copy generation limiting signals in byte PC1; and a
recording inhibit bit (RI) in byte PC4.
Subcode data is also recorded on the record medium in GL data pack
arrangement. The subcode region includes 1200 bits of a preamble, 1200
bits of a subcode area and 1325 (or 1200) bits of a postamble. Unlike the
audio and video regions, the preamble of the subcode region does not have
a pre-sync block and the postamble of the subcode region does not have a
post-sync block. This is because the subcode region is frequently
rewritten for indexing during a search, and updating the pre-sync and
post-sync blocks each time during the search is time consuming. The
subcode area preferably contains 12 subcode sync blocks with each subcode
sync block including 5 pre-sync bytes; 5 data bytes of auxiliary data; and
2 parity bytes C1 as shown in FIG. 12A, thus forming a 12-byte sync block.
The CGMS data of the AAUX and VAUX source control packs (FIGS. 14, 15) is
extracted therefrom and directly copied into the vertical blanking
interval data (VBID) of the digital video signal shown in FIG. 16. As
shown, the CGMS bits are inserted into BIT 7 and BIT 8 of the data section
of the VBID. It will be noted that the VBID also includes WIDE ID data
(bits 1 and 2) including a transmission aspect ratio (BIT 1) and a picture
display format (BIT 2); a MODE ID (bits 3-6) for indicating the mode of
the video signal; data bits 7-14; and CRCC information in bits 15-20.
CGMS Retrieval/TV Broadcast Detection
The present invention initially determines whether a video signal is a TV
broadcast signal and, if so, retrieves the CGMS data from the AAUX, VAUX
control source packs (FIGS. 14, 15). To identify a TV broadcast signal,
the present invention senses signals which are indicative of the TV
broadcast signal such as the Vertical Interval Test Signal (VITS) shown in
FIGS. 17A and 17B; or the Vertical Interval Reference Signal (VIR) shown
in FIG. 18. The VITS or the VIR signals are provided with the TV broadcast
signal and, therefore, identifying these signals determines that the
incoming video signal is a TV broadcast signal. It will be noted that the
VITS signal is inserted in both the first and second field of a frame, as
shown in FIGS. 17A, 17B, respectively. The VITS signal is inserted on line
17 of both fields in the CCIR 473 standard of the transmitted TV broadcast
signal, and in the United States, the VITS signal is inserted on lines 17
and 18 because the TBC transmission in the United States may cause the
VITS signal to be shifted by one line. Accordingly, the present invention
searches a range of lines 16, 17 and 18 to identify the VITS signal and
thereby detect the TV broadcast signal.
It will be appreciated that, unlike the digital VTR, the analog VTR records
the VITS or VIR signal along with the TV broadcast signal because the
analog VTR, unlike the digital VTR, does not cut off the vertical blanking
interval. Problematically, such an analog recorded TV broadcast signal
would be presented as an original TV broadcast signal (as opposed to a
copy) to the present invention. Fortunately, the analog VTR cannot sense
the high frequency, generally several Mhz, of the VITS or VIR signals.
Consequently, the analog VTR smooths the high frequency VITS and VIR
signals and the present invention does not erroneously detect a TV
broadcast signal therefrom. Even if the present invention senses
erroneously that the analog VTR output signal is an original TV broadcast
signal, the present invention treats analog output signals as if they
automatically have a copyright, and the analog output signal does not pose
a problem to the present invention.
It will also be appreciated that video signals pre-recorded on magnetic
tape or disk also contain the VBID signal or a copy-protect signal. The
present invention treats such pre-recorded signal as original TV broadcast
signals and automatically copyright protects those signals.
As shown in FIG. 19, the present invention when incorporated into a digital
VTR, detects a TV broadcast signal and sets the CGMS therefrom. That is,
when an analog video signal (composite video signal) is input, whether the
present invention senses a copy-protect signal (such as the type used by
Macrovision) is present in the input analog video signal in inquiry S1. If
so, it is assumed the input video signal is a copy and further copying is
prohibited by setting the CGMS="11" in instruction S2 (see FIG. 9).
But when no copy-protect signal is detected, the routine advances to
inquiry S3 to determine if a VBID signal is present in the input analog
video signal. If the VBID signal is detected, the routine determines that
the input video signal is received directly from a television broadcaster,
and is not pre-recorded or copied, for example. At this time, the routine
advances to inquiry S7 to determine whether the received video signal is
to be supplied to an analog video output or to a digital VTR output of the
digital VTR. If the video signal is to be supplied to the analog video
output, the routine extracts the CGMS data directly from the analog video
output in step S8; otherwise the CGMS is set according to the
predetermined values shown in step S9 if the video signal is to be
supplied to the digital VTR output.
If neither a copy-protect signal nor a VBID signal are detected, the
routine advances to inquiry S4 to determine whether a VITS signal is
present in the input analog video signal. If so, the routine allows the
corresponding input analog video signal to be copied once by setting the
CGMS bits="10" (see FIG. 9).
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