Electrical computers and digital data processing systems: input/ – Input/output data processing – Input/output command process
Reexamination Certificate
1998-12-02
2001-09-18
Lee, Thomas (Department: 2182)
Electrical computers and digital data processing systems: input/
Input/output data processing
Input/output command process
C710S005000, C710S068000, C710S069000
Reexamination Certificate
active
06292847
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a digital information reproducing apparatus and digital information distributing system. More particularly, this invention is concerned with a digital information reproducing apparatus and digital information distributing system that employ a semiconductor memory as a digital information storage medium, store digital information in a compressed and thus encoded state, and decode and reproduce the digital information.
2. Description of the Related Art
A digital information reproducing apparatus in accordance with a prior art which employs a semiconductor memory is, for example, described in Japanese Unexamined Patent Publication No. 3-139700.
FIG. 10
is a functional block diagram showing the outline configuration of a compact musical signal reproducing apparatus described in the patent publication.
As shown in
FIG. 10
, a compact musical signal reproducing apparatus
40
in accordance with the prior art has a semiconductor memory
41
, decoding circuit
42
, D/A converter
43
, and headphone unit
44
incorporated therein.
In the semiconductor memory
41
, musical digital data that has been encoded highly efficiently by an encoding circuit
33
is stored in advance. As stages preceding the encoding circuit
33
, an input terminal
31
and an A/D converter
32
are installed. A musical analog signal supplied through the input terminal
31
is converted into a digital signal by the A/D converter
32
and supplied to the encoding circuit
33
.
The musical digital data stored in the semiconductor memory
41
is decoded by the decoding circuit
42
in the apparatus
40
, and thus restored to an original musical digital signal. The digital signal is then converted into an analog electric signal by the D/A converter
43
, and converted into an acoustic signal by the headphone unit
44
. Eventually, music is output.
However, in the foregoing digital information reproducing apparatus of the prior art, the specified decoding circuit that has been incorporated in the course of manufacturing is used to decode data. Data that has been compressed and thus encoded in a different coding form cannot be reproduced at all. Thus, a problem of software incompatibility occurs.
SUMMARY OF THE INVENTION
The present invention attempts to solve the problem underlying the prior art. An object of the present invention is to improve a digital information reproducing apparatus and provide a digital information reproducing apparatus capable of coping with diverse compression coding forms.
For accomplishing the above object, the present invention provides a digital information reproducing apparatus comprising: a first semiconductor memory in which highly efficiently encoded digital data is stored; a second semiconductor memory in which decoding programs used to carry out decoding, which is inverse processing of high-efficiency encoding, are stored; and a decoding means for decoding the digital data stored in the first semiconductor memory according to a decoding program stored in the second semiconductor memory and associated with the digital data stored in the first semiconductor memory. A plurality of kinds of decoding programs is stored in the second semiconductor memory. The decoding means selects one of the plurality of kinds of decoding programs according to information concerning encoding appended to the digital data, and carries out decoding.
In the digital information reproducing apparatus, a decoding program stored in the second semiconductor memory and associated with digital data stored in the first semiconductor memory is used to decode the digital data stored in the first semiconductor memory. Information can therefore be reproduced from digital data irrespective of a compression coding form adopted for the digital data stored in the first semiconductor memory. Consequently, the digital information reproducing apparatus can cope with diverse compression coding forms.
Moreover, in the digital information reproducing apparatus, for example, a rewritable semiconductor memory such as a flash memory may be used as the whole or part of the second semiconductor memory. Even if an associated decoding program is not stored in the second semiconductor memory in advance, the contents of the second semiconductor memory may be updated in order to store a new decoding program therein. Consequently, digital signals conformable to more diverse compression coding forms can be reproduced. Moreover, at this time, the rewritable semiconductor memory need not be used as the whole of the second semiconductor memory but may be used as part thereof. In this case, only the portions of the decoding programs specialized according to a specified compression coding form may be stored in the rewritable memory. The fundamental portions thereof may be stored in a masked ROM or the like.
Furthermore, the digital information reproducing apparatus may include a read-only memory in which a common portion shared by the plurality of kinds of decoding programs is stored, a program storage memory in which the portions of the plurality of kinds of decoding program other than the common portion are stored, a selector for selecting a portion of a decoding program, which is selected to be associated with digital data to be decoded from among the plurality of kinds of decoding programs, other than the common portion from among the programs stored in the program storage memory, and a rewritable memory in which the program selected by the selector and copied from the program storage memory is stored.
Owing to the above configuration, the number of memories in the digital information reproducing apparatus can be decreased, the time required to load a program to an arithmetic circuit can be shortened, and the whole apparatus can be reduced in scale. Moreover, a plurality of non-common portion programs may be made available in advance but a non-common portion program may not be rewritten externally. In this case, even a simple selector can select a non-common portion program that should be adopted at that time. Consequently, decoding is executed as if it were executed in a reproducing apparatus dedicated to decoding.
Moreover, in the digital information reproducing apparatus, a rewritable memory, for example, a flash memory may be used as the whole or part of the first semiconductor memory. In this case, not only reproducing digital data but also recording it at a high speed can be achieved.
Moreover, in the digital information reproducing apparatus, a receiver for receiving digital data externally may be included. In this case, digital data can be updated readily.
Moreover, in the digital information reproducing apparatus, all or part of the decoding programs may be stored in the second semiconductor memory via the receiver. In this case, for example, a decoding program associated with digital data stored in the first semiconductor memory may not be stored in the second semiconductor memory. Nevertheless, an associated decoding program can be obtained via the receiver. Consequently, digital information structured according to more diverse compression coding forms can be reproduced.
Moreover, in the digital information reproducing apparatus, the whole or part of the second semiconductor memory may be a detachable module. Otherwise, the whole of part of the first semiconductor memory may be a detachable module. In this case, digital data or decoding programs can be replaced with another readily. The storage capacity of the first or second semiconductor memory can be increased according to a situation. The digital data or decoding programs can be distributed to the others readily.
Moreover, in the digital information reproducing apparatus, the first semiconductor memory may be composed of a plurality of blocks. Digital data may then be stored so that the start thereof will appear at the start of a block. In this case, a specified portion of the digital data can be deleted comprehensively without the need of complex addressing. Eventually, the efficiency in
Harada Kazushige
Morita Takashi
Nishimoto Yoshiro
Shimoda Toshiaki
Takahashi Tetsuya
Cao Chun
Kabushiki Kaisha Kobe Seiko Sho.
Lee Thomas
Reed Smith Hazel & Thomas LLP
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