Sound encoder and sound encoding method
View Patent ↗Even when a combination of the stegonography technique and prediction encoding is applied to sound encoding, a sound encoder does not cause deterioration in quality of decoded signals. In the device, an encoding section ( 102 ) outputs an encoding code (I) to a bit embedding section ( 104 ). A function extension encoding section ( 103 ) generates an encoding code (J) for information required for extending functions of the sound encoder ( 100 ) and outputs it to the bit embedding section ( 104 ). The bit embedding section ( 104 ) embeds information on the encoding code (J) into a part of bits of the encoding code (I) and outputs the resultant encoding code (I′). A synchronization information generating section ( 106 ) generates synchronization information according to the encoding code (I′) after the bit embedding and outputs the synchronization information to the encoding section ( 102 ). The encoding section ( 102 ) updates the internal state and the like on the basis of the synchronization information and encodes the next digital sound signal (X).
1. A speech encoding apparatus comprising:
an encoding section that generates a first code from a speech signal using predictive encoding;
an embedding section that embeds additional information in the first code to obtain a second code;
a re-encoding section that re-encodes the speech signal to generate a third code and a predictive parameter used in the predictive encoding using the second code, under restriction of holding the additional information within the second code; and
an updating section that updates another predictive parameter held in the encoding section, using the predictive parameter generated in the re-encoding section.
2. The speech encoding apparatus according to claim 1 , wherein:
the encoding section generates the first code using an ADPCM (Adaptive Differential Pulse Code Modulation) scheme; and
the embedding section embeds the additional information in an LSB (Least Significant Bit) of the first code.
3. The speech encoding apparatus according to claim 1 , wherein:
the encoding section generates the first code using a CELP scheme; and
the embedding section embeds the additional information in a code indicating a CELP scheme excitation source, out of the first code.
4. The speech encoding apparatus according to claim 1 , wherein the embedding section changes a number of bits of the embedded additional information according to a property of the speech signal, and reports the number of bits to a speech decoding apparatus.
5. The speech encoding apparatus according to claim 1 , further comprising a designation section that designates a number of bits of the additional information from predetermined options.
6. A communication terminal apparatus comprising the speech encoding apparatus according to claim 1 .
7. The communication terminal apparatus according to claim 6 , further comprising a transmission section that signals a position where the embedding section embeds the additional information and a number of bits of the additional information.
8. The communication terminal apparatus according to claim 7 , wherein the embedding section decides a position for embedding the additional information according to reception conditions of a communication terminal apparatus of a communicating party.
9. A base station apparatus comprising the speech encoding apparatus according to claim 1 .
10. The base station apparatus according to claim 9 , further comprising a transmission section that signals a position where the embedding section embeds the additional information and a number of bits of the additional information.
11. The base station apparatus according to claim 10 , wherein the embedding section decides a position for embedding the additional information according to reception conditions of a communication terminal apparatus of the communicating party.
12. A speech encoding method comprising:
an encoding step of generating a first code from a speech signal using predictive encoding;
an embedding step of embedding additional information in the first code to obtain a second code;
a re-encoding step of re-encoding the speech signal to generate a third code and a predictive parameter used in the predictive encoding using the second code, under restriction of holding the additional information within the second code; and
an updating step of updating another predictive parameter used in the encoding step, using the predictive parameter.