Encoding apparatus and decoding apparatus

• US 7,124,076 B2
• Filed: 12/14/2001
• Issued: 10/17/2006
• Est. Priority Date: 12/14/2000
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Tsuji, Minoru, Toyama, Keisuke, Suzuki, Shiro
• Primary Examiner(s): Knepper, David D.
• Application Number:
  US10/203,775
• Publication Number:
  US 20030138057A1
• Time in Patent Office: 1,768 Days
• Field of Search: None
• US Class Current: 704/205
• CPC Class Codes: G10L 19/0204 using subband decomposition
• CPC Class Codes: G10L 19/025 Detection of transients or attacks for time/frequency resolution switching
• CPC Class Codes: H03M 7/30 Compression speech analysis-synthesis for redundancy reduction G10L19/00; for image communication H04N; Expansion; Suppression of unnecessary data, e.g. redundancy reduction
• CPC Class Codes: H04B 1/667 using a division in frequency subbands for TV signals H04N19/63
• CPC Class Codes: H04B 14/046 Systems or methods for reducing noise or bandwidth
• CPC Class Codes: H04L 25/062 Setting decision thresholds using feedforward techniques only

Abstract

The present invention relates to encoding apparatuses which allow encoding to be performed such that the occurrence of pre-echo and post-echo is suppressed. A predetermined waveform analysis is applied to a low-frequency-component input time-sequential signal which includes a high-frequency component occurring at a specific time, and a low-frequency-component time-sequential signal like that shown in FIG. 9A is generated according to a result of the analysis. The low-frequency-component time-sequential signal is removed from the input time-sequential signal to generate a residual time-sequential signal like that shown in FIG. 9B. An amplitude control process is applied such that the amplitude of the residual time-sequential signal is made almost constant in a block which serves as a unit of encoding to generate a time-sequential signal to be quantized, like that shown in FIG. 9C. The time-sequential signal to be quantized is quantized and encoded. The present invention can be applied to audio recording and reproduction apparatuses.

Claims

1. An encoding apparatus characterized by comprising:

division means for dividing an input time-sequential signal into predetermined-length blocks;

low-frequency-component-signal generation means for applying a predetermined frequency analysis to the input time-sequential signal in the blocks and for generating a low-frequency-component signal according to predetermined waveform information based on a result of the analysis;

residual-signal generation means for removing the low-frequency-component signal from the input time-sequential signal in the blocks to generate a residual signal;

amplitude control process means for analyzing the amplitude of the residual signal and for applying a predetermined amplitude control process to the residual signal according to predetermined amplitude control process information based on a result of the analysis to generate a signal to be quantized;

quantization means for quantizing the signal to be quantized to generate a quantized signal; and

code-string generation means for encoding the waveform information, the amplitude control process information, and the quantized signal to generate a code string.

2. An encoding apparatus according to claim 1, characterized in that

the quantization means comprises:

frequency-component generation means for converting the signal to be quantized to frequency components to generate a frequency-component signal; and

means for normalizing and quantizing the frequency-component signal to generate the quantized signal.

3. An encoding apparatus according to claim 2, characterized in that

the frequency-component generation means applies spectrum conversion to the signal to be quantized to generate the frequency-component signal.

4. An encoding apparatus according to claim 1, characterized in that

the low-frequency-component-signal generation means performs the frequency analysis according to a general harmonic analysis method, and generates the low-frequency-component signal according to the waveform information based on a result of the analysis.

5. An encoding apparatus according to claim 1, characterized in that

the low-frequency-component-signal generation means quantizes the waveform information to generate quantized waveform information, dequantizes the quantized waveform information to generate dequantized waveform information, and generates the low-frequency-component signal according to the dequantized waveform information;

and

the code-string generation means encodes the quantized waveform information, the amplitude control process information, and the quantized signal to generate the code string.

6. An encoding apparatus according to claim 1, characterized in that

the division means divides the input time-sequential signal into the blocks such that a part of the input time-sequential signal overlaps;

and

the low-frequency-component-signal generation means synthesizes a low-frequency-component signal in a block concerned, a low-frequency-component signal in the previous block, overlapping with the signal in the block concerned, and a low-frequency-component signal in the next block, overlapping with the signal in the block concerned, in a time domain to generate a low-frequency-component signal.

7. An encoding apparatus according to claim 6, characterized in that the low-frequency-component-signal generation means applies a window function to the low-frequency-component signal.

8. An encoding apparatus for dividing an input time-sequential signal into M band signals, for dividing the band signals into predetermined blocks, and for encoding them, characterized by comprising:

low-frequency-component-signal generation means for applying a predetermined frequency analysis to a signal in a block of at least one band signal and for generating a low-frequency-component signal according to predetermined waveform information based on a result of the analysis;

residual-signal generation means for removing the low-frequency-component signal from the band signal to generate a residual signal; and

amplitude control process means for analyzing the amplitude of the residual signal and for applying a predetermined amplitude control process to the residual signal according to predetermined amplitude control process information based on a result of the analysis to generate a signal to be quantized.

9. An encoding method characterized by comprising:

a division step of dividing an input time-sequential signal into predetermined-length blocks;

a low-frequency-component-signal generation step of applying a predetermined frequency analysis to the input time-sequential signal in the blocks and of generating a low-frequency-component signal according to predetermined waveform information based on a result of the analysis;

a residual-signal generation step of removing the low-frequency-component signal from the input time-sequential signal in the blocks to generate a residual signal;

an amplitude control process step of analyzing the amplitude of the residual signal and of applying a predetermined amplitude control process to the residual signal according to predetermined amplitude control process information based on a result of the analysis to generate a signal to be quantized;

a quantization step of quantizing the signal to be quantized to generate a quantized signal; and

a code-string generation step of encoding the waveform information, the amplitude control process information, and the quantized signal to generate a code string.

10. A recording medium storing a computer-readable program, the program characterized by comprising:

a division step of dividing an input time-sequential signal into predetermined-length blocks;

a low-frequency-component-signal generation step of applying a predetermined frequency analysis to the input time-sequential signal in the blocks and of generating a low-frequency-component signal according to predetermined waveform information based on a result of the analysis;

a residual-signal generation step of removing the low-frequency-component signal from the input time-sequential signal in the blocks to generate a residual signal;

an amplitude control process step of analyzing the amplitude of the residual signal and of applying a predetermined amplitude control process to the residual signal according to predetermined amplitude control process information based on a result of the analysis to generate a signal to be quantized;

a quantization step of quantizing the signal to be quantized to generate a quantized signal; and

a code-string generation step of encoding the waveform information, the amplitude control process information, and the quantized signal to generate a code string.

11. A decoding apparatus for receiving a code string generated by encoding a time-sequential signal in each block and for decoding it, characterized by comprising:

decomposition means for decomposing the code string into waveform information, amplitude control process information, and a quantized signal;

means for dequantizing the quantized signal;

inverse amplitude control process means for applying an amplitude control process inverse to that performed in encoding, to the dequantized signal according to the amplitude control process information to generate a signal to which the amplitude control process has been applied;

low-frequency-component-signal generation means for generating a low-frequency-component signal according to the waveform information; and

means for generating a time-sequential signal from the signal to which the amplitude control process has been applied, and the low-frequency-component signal.

12. A decoding apparatus according to claim 11, characterized in that

when the waveform information has been quantized, the low-frequency-component-signal generation means dequantizes the quantized waveform information and, according to information obtained as a result, generates the low-frequency-component signal.

13. A decoding apparatus according to claim 11, characterized in that

when division has been made such that a part of the blocks overlap, the low-frequency-component-signal generation means synthesizes a low-frequency-component signal in a block concerned, a low-frequency-component signal in the previous block, overlapping with the signal in the block concerned, and a low-frequency-component signal in the next block, overlapping with the signal in the block concerned, in a time domain to generate a low-frequency-component signal.

14. A decoding method for receiving a code string generated by encoding a time-sequential signal in each block and for decoding it, characterized by comprising:

a decomposition step of decomposing the code string into waveform information, amplitude control process information, and a quantized signal;

a step of dequantizing the quantized signal;

an inverse amplitude control process step of applying an amplitude control process inverse to that performed in encoding, to the dequantized signal according to the amplitude control process information to generate a signal to which the amplitude control process has been applied;

a low-frequency-component-signal generation step of generating a low-frequency-component signal according to the waveform information; and

a step of generating a time-sequential signal from the signal to which the amplitude control process has been applied, and the low-frequency-component signal.

15. A recording medium storing a computer-readable program for a decoding apparatus which receives a code string generated by encoding a time-sequential signal in each block and decodes it, the program characterized by comprising:

a decomposition step of decomposing the code string into waveform information, amplitude control process information, and a quantized signal;

a step of dequantizing the quantized signal;

an inverse amplitude control process step of applying an amplitude control process inverse to that performed in encoding, to the dequantized signal according to the amplitude control process information to generate a signal to which the amplitude control process has been applied;

a low-frequency-component-signal generation step of generating a low-frequency-component signal according to the waveform information; and

a step of generating a time-sequential signal corresponding to an encoded time-sequential signal, from the signal to which the amplitude control process has been applied, and the low-frequency-component signal.