Dynamic information storage or retrieval – Control of storage or retrieval operation by a control...
Reexamination Certificate
2002-09-12
2004-07-06
Hindi, Nabil (Department: 2653)
Dynamic information storage or retrieval
Control of storage or retrieval operation by a control...
C369S059210, C369S059230
Reexamination Certificate
active
06760286
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a method of transmitting data among a plurality of LSIs (Large Scale Integrated Circuits) which are connected to one another through an external bus, and more particularly, to a method of transmitting, in a DVD (Digital Versatile Disk) audio reproducing apparatus comprising a digital signal processing LSI and a D/A (Digital-to-Analog) converting LSI which are connected to each other through an external bus, a digital signal from the digital signal processing LSI to the D/A converting LSI through the external bus, and the DVD-Audio reproducing apparatus using the method.
2. Description of the Background Art
In recent years, A DVD-Audio standard for realizing multi-channel reproduction of a high-quality sound by recording mainly an audio signal on a DVD having a capacity of 4.7 GB in a single-sided one layer system has been determined, and a DVD-Audio reproducing apparatus for reproducing a DVD-Audio disk has been developed.
In the DVD-Audio standard, audio signals having various sampling frequencies, various numbers of quantization bits, and various numbers of channels can be recorded and reproduced. For example, an audio signal having a sampling frequency of 192 kHz, 24 quantization bits, and two channels can be recorded to reproduce a stereo sound having a maximum frequency of 96 kHz. Alternatively, an audio signal having a sampling frequency of 96 kHz, 24 quantization bits, and six channels can be recorded to reproduce a multi-channel sound having a maximum frequency of 48 kHz. Further, a variety of recording and reproduction can be performed. For example, a video signal is recorded on the DVD to reproduce an image together with a sound.
Examples of the sampling frequency of the audio signal include 192/96/48 kHz and 176.4/88.2/44.1 kHz. An example of the quantization bits are 24/20/16 bits.
FIG. 11
is a diagram showing the configuration of a portion related to the transmission of a digital signal from a digital signal processing LSI
6
to a D/A converting LSI
7
in a conventional DVD-Audio reproducing apparatus
In
FIG. 11
, the digital signal processing LSI
6
and the D/A converting LSI
7
are connected to each other through external buses
13
to
15
. The digital signal processing LSI
6
processes an incoming digital signal (a packet stream), to generate a digital signal. The D/A converting LSI
7
converts the digital signal outputted from the digital signal processing LSI
6
into an analog signal.
FIG. 12
is a timing chart showing the digital signal outputted from the digital signal processing LSI
6
shown in
FIG. 11
(in a case where the number of channels is
2
). In
FIG. 12
, a word clock is a clock signal representing the timing at which channels in serial data are switched, and is transmitted through the external bus
13
shown in FIG.
11
. The serial data includes data representing two channels (ch1 and ch2), and is transmitted through the external bus
14
(when the number of channels is four, for example, another serial data including two channels (ch3 and ch4) is outputted in parallel with the serial data). A bit clock is a clock signal which is synchronized with the serial data, and is transmitted through the external bus
15
A bit array {MSB, 23, 22, 3, 2, LSB} on each of the channels ch1 and ch2 is obtained from the word clock, the serial data, and the bit clock
As described above, in the conventional DVD-Audio reproducing apparatus, the digital signal processing LSI
6
and the D/A converting LSI
7
are provided on separate chips, and are connected to each other through the external buses
13
to
15
. Therefore, the digital signal can be taken out of the external buses
13
to
15
between the digital signal processing LSI
16
and the D/A converting LSI
7
and unfairly copied. An ultrahigh-quality stereo sound and a high-quality multi-channel sound, as described above, can be easily reproduced from the digital signal immediately before being inputted to the D/A converting LSI
7
(see FIG.
12
).
If the digital signal processing LSI
6
and the D/A converting LSI
7
are provided on a single chip, it is possible to prevent the digital signal from being taken out of the external buses
13
to
15
and unfairly copied. In this case, however, noises and the like due to digital signal processing performed on the digital signal processing LSI
6
are included into an analog circuit portion included in the D/A converting LSI
7
. As a result, another problem occurs. For example, the quality of an analog signal outputted from the D/A converting LSI
7
is degraded. When a DVD-Audio is reproduced, higher-speed digital signal processing (as compared with that in CD reproduction, for example) is performed, so that the quality is significantly degraded.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide a DVD-Audio reproducing apparatus capable of preventing a digital signal immediately before being inputted to a D/A converting LSI from being taken out and unfairly copied.
The present invention has the following features to solve the problem above
A first aspect of the present invention is directed to a method of transmitting data between a first LSI and a second LSI which are connected to each other through an external bus The method comprises scrambling the data inside the first LSI, transmitting the scrambled data from the first LSI to the second LSI through the external bus, and descrambling the scrambled data inside the second LSI
In the first aspect, the signal transmitted through the external bus between the first LSI and the second LSI is scrambled. Accordingly, even if the data is taken out of the external bus and unfairly copied, the data cannot be reproduced.
A second aspect is directed to a method of transmitting, in a DVD-Audio reproducing apparatus comprising a digital signal processing LSI and a D/A converting LSI which are connected to each other through an external bus for reproducing a DVD-Audio disk, a digital signal from the digital signal processing LSI to the D/A converting LSI through the external bus. The method comprises, inside the digital signal processing LSI, processing the digital signal which has been read out of the DVD-Audio disk, and scrambling the digital signal which has been processed, transmitting the scrambled digital signal from the digital signal processing LSI to the D/A converting LSI through the external bus, and, inside the D/A converting LSI, descrambling the scrambled digital signal transmitted through the external bus and converting the digital signal which has been descrambled into an analog signal.
In the second aspect (and in the following third aspect), the digital signal transmitted through the external bus between the digital signal processing LSI and the D/A converting LSI is scrambled. Accordingly even if the digital signal is taken out of the external bus and unfairly copied, the digital signal cannot be reproduced.
A third aspect is directed to a DVD-Audio reproducing apparatus for reproducing a DVD-Audio disk. The apparatus comprises a digital signal processing LSI and a D/A converting LSI, which are connected to each other through an external bus The digital signal processing LSI comprises digital signal processing means for processing a digital signal which has been read out of the DVD-Audio disk, and scrambling processing means for scrambling the digital signal outputted from the digital signal processing means. The D/A converting LSI comprises descrambling processing means for descrambling the scrambled digital signal transmitted through the external bus, and D/A conversion means for converting the digital signal outputted from the descrambling processing means into an analog signal.
According to a first embodiment, the apparatus further comprises header reading means for reading attribute information relating to a digital signal, which has been read out of the DVD-Audio disk, described in a header attached to each of packets composing the digital s
Kawamura Akihisa
Mori Yoshihiro
Shimbo Masatoshi
Hindi Nabil
Matushita Electric Industrial Co. Ltd.
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