Image analysis – Applications
Reexamination Certificate
2000-02-03
2004-04-13
Patel, Jayanti K. (Department: 2625)
Image analysis
Applications
C382S235000, C382S251000, C382S250000, C713S176000, C380S200000
Reexamination Certificate
active
06721437
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a technique for controlling copying of multimedia data composed of a video signal, an audio signal and so forth, and more particularly to a data processing apparatus wherein a decoder for decoding an electronic watermark (digital watermark) for copy control is built in an encoder for coding a video signal and/or an audio signal in order to protect the video signal and/or the audio signal against alteration.
Prevention of illegal copying or alteration of music or acoustic data (hereinafter referred to as audio signal) recorded on a CD (compact disc), prevention of illegal copying or alteration of a video signal (image signal) and an audio signal recorded on a DVD (digital video disc), prevention of illegal use or alteration of multimedia data transmitted over a digital broadcasting network and other protection of the copyright of multimedia data have been attempted from various points of view.
From the point of view of protection of the copyright, various attempts have been made to prevent illegal copying of literary works of multimedia data such as, for example, an image signal (or video signal) and an audio signal. It is to be noted that such information may sometimes be hereinafter referred to as contents.
FIG. 1
shows a concept of a system which carries out a copy control method.
Referring to
FIG. 1
, in order to effect copy control, an apparatus (signaling section)
110
on the source side signals copy control information together with contents (information) into a signal transmission path
120
so as to be transmitted to a recording apparatus
130
on the reception side. The signal transmission path
120
may take various forms such as broadcasting, package media and network distribution. A copy control information detection circuit
134
of the reception side recording apparatus
130
detects the copy control information from the contents transmitted thereto and produces a recording operation control signal representative of whether or not recording is permitted. A recording processing circuit
132
records the received contents onto a recording medium such as, for example, a CD only when the recording operation control signal indicates permission of recording. Naturally, if the recording operation control signal indicates inhibition of recording, the recording processing circuit
132
does not perform a recording operation onto the recording medium.
However, while the recording operation control signal originally indicates inhibition of recording (inhibition of copying), if it is altered so that it indicates permission of recording (permission of copying), then a recording operation onto the recording medium is performed by the recording processing circuit
132
. Therefore, such alteration of the recording operation control signal must be prevented. Now, a method of such prevention is described.
FIG. 2
illustrates an example of copy control information for a digital audio signal.
Referring to
FIG. 2
, the copy control signal for a digital audio signal includes a bit representative of presence or absence of copyright, a generation bit and a category bit in a digital interface illustrated in
FIG. 2
in accordance with the provisions of the SCMS (Serial Copy Management System). The copy control signal is multiplexed into contents of a signal addition section
112
of the source side apparatus
110
, in this instance, into a digital audio signal, and transmitted over the signal transmission path
120
to the reception side recording apparatus
130
such as, for example, a DAT (Digital Audio Tape) recording apparatus or an MD (Mini Disc: trademark) recording apparatus. Then, the copy control signal is detected by the copy control information detection circuit
134
of the reception side recording apparatus
130
and used to control recording of the recording processing circuit
132
.
An example of copy control information for a video signal is illustrated in
FIGS. 3A and 3B
.
Referring to
FIGS. 3A and 3B
, CGMS (Copy Generation Management System) bits are multiplexed into contents, in this instance, into a video signal, by the signal addition section
112
of the source side apparatus
110
within a VBI (vertical blanking interval) and transmitted to the signal transmission path
120
. Then, the CGMS bits are detected by the copy control information detection circuit
134
of the reception side recording apparatus
130
such as a DVD recording apparatus and used to control recording processing of the recording processing circuit
132
.
The SCMS bits for an audio signal and the CGMS bits for a video signal described above are laid open as formats for transmission systems and can be acquired readily by a third party. Therefore, there is the possibility that, although a copy control signal or a recording operation control signal indicates inhibition of copying, it may be altered so as to indicate permission of copying.
As a countermeasure for overcoming the problem just described, several methods which provide augmented security have been proposed. One of the proposed methods employs a SDS (Secure Digital Bus) system, and another one of the methods adopts an electronic watermark.
FIG. 4
shows a system which employs a SDS system.
Referring to
FIG. 4
, in the SDS (Secure Digital Bus) system, an authentication-key exchange section
144
of a transmission side apparatus
140
exchanges information of a key and so forth with an authentication-key exchange section
164
of a reception section
160
, which is the other party of communication, over a signal transmission section
150
which has an IEEE (Institute of Electrical and Electronics Engineers)
1394
digital interface. The transmission side apparatus
140
side authenticates whether or not a decryption section
162
which is the other party of communication has a copy control function legally. Then, only if the other party has a legal copy control function, original contents S
0
are encrypted by an encryption section
142
and transmitted to the reception section
160
over the signal transmission section
150
. The original contents S
0
in this instance may be one or both of a video signal and an audio signal or multimedia data.
In the SDB system, even if the signal transmission section
150
tries to alter a signal on the digital interface, this is impossible if a third party who tries to illegally use the transmission signal cannot decrypt the signal. Accordingly, the SDB system is considered to be an information transmission system which is high in security in a transmission path.
The electronic watermark (digital watermark, digital data embedding, or digital data hiding) technique embeds some information into contents so that the contents may have the information in a hidden state. When an electronic watermark is embedded into contents, for example, into a video signal, the electronic watermark is embedded into the video signal in such a form that it cannot be perceived (visually observed) readily by the eyes of a human being while the video signal itself is maintained. When an electronic watermark is embedded into an audio signal, it is embedded in such a form that it cannot be perceived readily by the sense of hearing of a human being while the audio signal itself is maintained.
It has been proposed to combine such an electronic watermark technique as described above with an illegal copying prevention technique for digital literary works (for example, “The ‘Electronic Watermark’ Protects the Multimedia Age”,
Nikkei Electronics
, Feb. 24, 1997, pp.99-124).
Various methods have been proposed to embed electronic watermark information into digital multimedia data. An exemplary one of the methods is described.
FIGS. 5A
,
5
B and
5
C illustrate an example of an electronic watermark for an audio signal.
According to the electronic watermark technique, the following processing is performed. First, frequency components of the audio signal are analyzed to select those frequency components f
1
, f
2
, f
3
and f
4
(indicated by slanting lines in
FIG. 5A
) whose
Ezaki Tadashi
Sato Hideo
Choobin Barry
Frommer William S.
Frommer & Lawrence & Haug LLP
Mahr Hans R.
Patel Jayanti K.
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