Data processing: speech signal processing – linguistics – language – Speech signal processing – Application
Reexamination Certificate
2000-09-08
2003-03-25
To, Doris H. (Department: 2654)
Data processing: speech signal processing, linguistics, language
Speech signal processing
Application
C704S201000, C704S230000, C704S204000, C704S222000
Reexamination Certificate
active
06539356
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an encoding method for combining and encoding a vibration wave such as a voice signal with other data such as text data indicating a document and authentication data indicating a transmitter and a decoding method.
BACKGROUND OF THE INVENTION
As a conventional encoding technique for transmitting or accumulating a voice as one of vibration waves, there is a technique which uses vector quantization (VQ) for regarding N sample values of a voice waveform as an N-dimensional vector, and encoding the vector (specifically, vector data consisting of N sample values, further the vector data indicating the waveform for a predetermined time in the voice waveform) into one code.
Moreover, in the encoding system using the vector quantization, voice is encoded in a procedure of: successively inputting the above-described vector data; selecting the representative vector data most approximate to the currently inputted vector data from a codebook for storing a plurality of representative vector data successively numbered beforehand every time the vector data is inputted; and outputting binary data indicating the number of the selected representative vector data as the code indicating the currently inputted vector data.
Moreover, to reproduce the voice, by successively inputting the encoded code, extracting the representative vector data of the number indicated by the code from the same codebook as the codebook used during encoding every time the code is inputted, and reproducing the waveform corresponding to the currently inputted code from the extracted representative vector data, the voice waveform is restored.
Moreover, as the representative encoding system using this vector quantization, code excited linear prediction (CELP) encoding, and 16 kbit/s low delay code excited linear prediction encoding (LD-CELP: Low Delay-CELP) of the International Telecommunication Union (ITU)-T Recommendation G.728, and the like are exemplified.
Additionally, the above-described LD-CELP uses CELP as a principle, and is known as a method with little encoding delay regardless of a low bit rate. Moreover, CELP or LD-CELP is described in detail, for example, in document
1
“Recommendation G.728, ITU (1982)”, document
2
“High Efficiency Voice Encoding Technique for Digital Mobile Communication, authored by Kazunori OZAWA,. Kabushiki Kaisha Trikeps (1992)”, document
3
“International Standard of Multimedia Encoding, authored by Hiroshi YASUDA, Maruzen Co., Ltd. (1991)”, and the like.
Additionally, since the digital code of the voice encoded by this encoding system (voice code) can easily be duplicated, there is a fear of secondary use without any permission. Therefore, there is a problem that it is difficult to protect digitized works.
In recent years, as a countermeasure of the problem, the application of electronic watermark has been studied. Specifically, other data such as the authentication data indicating the caller is secretly combined and embedded in the voice code.
However, a preferred method by which other data can secretly be combined (embedded) with the voice code encoded by the above-described vector quantization has not been considered. Moreover, if the other data is simply combined, there is a high possibility that the other combined data is easily deciphered by the third party.
Therefore, when the vibration wave other than a voice signal, such as an analog signal outputted from a sensor, a measuring instrument or the like is encoded by the vector quantization, the electronic watermarking for combining the code with other data such as the authentication data indicating a utilizer and the text data indicating document cannot be performed.
The present invention has been developed in consideration of the problem, and an object thereof is to provide a method of encoding a vibration wave which can secretly be combined with another data during the encoding of a vibration wave such as a voice signal by vector quantization, and a method of decoding the vibration wave in which another data can securely be extracted from the code generated by the encoding method.
SUMMARY OF THE INVENTION
In a vibration wave encoding method of the present invention which has been developed to achieve the above-described object, every time the vector data indicating a waveform of a vibration wave for a predetermined time is inputted, the representative vector data most approximate to the currently inputted vector data is selected from a codebook for storing a plurality of representative vector data successively numbered beforehand, and binary data indicating the number of the selected representative vector data is outputted as the code indicating the currently inputted vector data.
Specifically, the vibration wave is encoded by the vector quantization represented by the above-described CELP or LD-CELP, but during the encoding, the information of the vibration wave is combined with other information by embedding the data constituting the other information in the code to be outputted by the following procedure.
First, division instruction information indicating that each representative vector data stored in the codebook belongs to either a first group or a second group is pre-stored in predetermined memory means.
Subsequently, by reading another binary data to be combined with the vibration wave before selecting the representative vector data most approximate to the currently inputted vector data, selecting the representative vector data most approximate to the currently inputted vector data only from the representative vector data belonging to the first group as indicated by the division instruction information stored in the memory means in the representative vector data stored in the codebook when the read binary data is “0”, or selecting the representative vector data most approximate to the currently inputted vector data only from the representative vector data belonging to the second group as indicated by the division instruction information stored in the memory means in the representative vector data stored in the codebook when the read binary data is “1” the code indicating the currently inputted vector data is combined with the read binary data.
Therefore, when the read binary data is “0” the outputted code is binary data indicating any number of the representative vector data belonging to the first group, and conversely when the read binary data is “1” the outputted code is binary data indicating any number of the representative vector data belonging to the second group.
Specifically, in the vibration wave encoding method of the present invention, by switching the selection range of the representative vector data in the codebook to the first group and the second group determined by the division instruction information in accordance with the other binary data to be combined, the binary data of the other information is combined (embedded) in the code indicating the inputted vector data.
On the other hand, the vibration wave is restored and the binary data combined as described above can be separated from the code generated by the encoding method by the decoding method of the present invention.
First, in the decoding method of the present invention, every time the code generated by the above-described encoding method is successively inputted, by extracting the representative vector data of the number indicated by the code from the same codebook as the codebook, and reproducing the waveform corresponding to the currently inputted code from the extracted representative vector data, the vibration wave is restored. Specifically, the vibration wave is reproduced by the decoding procedure of the encoding system using the vector quantization.
Here, the division instruction information is stored in predetermined memory means.
Moreover, to perform the decoding as described above, by determining that the code is combined with the binary data “0” when the number indicated by the currently inputted code is the number of the representative vector data belonging to the first grou
Iwakiri Munetoshi
Matsui Kineo
Kowa Co. Ltd.
Nolan Daniel A
To Doris H.
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