Signal Processing Apparatus and Method, and Program

• US 20100106494A1
• Filed: 06/26/2008
• Published: 04/29/2010
• Est. Priority Date: 07/30/2007
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Honma, Hiroyuki
• Granted Patent: US 8,478,586 B2
• Time in Patent Office: Days
• US Class Current: 704/224
• CPC Class Codes: G10L 19/03 Spectral prediction for preventing pre-echo; Temporary noise shaping [TNS], e.g. in MPEG2 or MPEG4

Abstract

A coded code string from an input terminal 110 is demultiplexed by a demultiplexer circuit 101, normalization coefficient information in the code string is sent to a normalization coefficient information increasing/decreasing circuit 102, addition or subtraction of a positive value is performed, and level adjustment of a signal is performed. A normalization coefficient information cutoff amount calculating circuit 103 calculates the cutoff amount for a case where the subtraction amount of normalization coefficient information is larger than normalization coefficient information and normalization coefficient information after subtraction is cut off at the minimum possible value. A gain control function generation information modifying circuit 104 modifies gain control function generation information according to the cutoff amount.

Claims

1. A signal processing apparatus that performs signal processing on a code string obtained by dividing an input digital signal into blocks along the time axis, performing gain control on each block along the time axis, normalizing with a positive value a signal component on which the gain control has been performed, quantizing the normalized signal component, and coding and multiplexing along with gain control function generation information generating a gain control function for performing the gain control and normalization coefficient information, the signal processing apparatus comprising:

normalization coefficient information increasing/decreasing means for adjusting a level of the signal by, for the coded code string, subtracting or adding an integer value from/to the normalization coefficient information in the code string;

cutoff amount calculating means for calculating a cutoff amount for a case where the normalization coefficient information after subtraction or addition is cut off at a minimum or maximum possible value thereof because a subtracted or added amount of the normalization coefficient information is large; and

modifying means for modifying the gain control function generation information according to the cutoff amount from the cutoff amount calculating means.

2. The signal processing apparatus according to claim 1, wherein

the cutoff amount calculating means calculates the cutoff amount for a case where the subtracted amount of normalization coefficient information is larger than the normalization coefficient information and the normalization coefficient information after subtraction is cut off at the minimum possible value thereof.

3. The signal processing apparatus according to claim 1, wherein

the cutoff amount calculating means calculates the cutoff amount for a case where the added amount of normalization coefficient information is large and the normalization coefficient information after addition is cut off at the maximum possible value thereof.

4. The signal processing apparatus according to claim 1, wherein

the signal component on which the gain control is performed is a subband signal obtained by using a subband dividing filter on the input digital signal.

5. The signal processing apparatus according to claim 1, wherein

the signal component which is normalized is an MDCT coefficient obtained by performing MDCT (Modified Discrete Cosine Transform) after performing the gain control.

6. The signal processing apparatus according to claim 5, wherein

the normalizing is performed on each of a plurality of the MDCT coefficients, and a plurality of pieces of the normalization coefficient information are obtained as an output of the normalizing.

7. The signal processing apparatus according to claim 1, wherein

the gain control function generation information is modified only when the code string includes the gain control function generation information.

8. A signal processing method of performing signal processing on a code string obtained by dividing an input digital signal into blocks along the time axis, performing gain control on each block along the time axis, normalizing with a positive value a signal component on which the gain control has been performed, quantizing the normalized signal component, and coding and multiplexing along with gain control function generation information on generating a gain control function for performing the gain control and normalization coefficient information, the signal processing method comprising the steps of:

adjusting a level of the signal by, for the coded code string, adding or substracting an integer value to/from the normalization coefficient information in the code string; and

modifying gain control function generation information according to the cutoff amount, if a subtracted amount of the normalization coefficient information is larger than the normalization coefficient information and the normalization coefficient information after subtraction is cut off at a minimum possible value thereof.

9. The signal processing method according to claim 8, further comprising the step of modifying the gain control function generation information according to the cutoff amount, if an added amount of the normalization coefficient information is large and the normalization coefficient information after addition is cut off at a maximum possible value thereof.

10. A program for causing a computer to execute a signal processing to be performed on a code string obtained by dividing an input digital signal into blocks along the time axis, performing gain control on each block along the time axis, normalizing with a positive value a signal component on which the gain control has been performed, quantizing the normalized signal component, coding and multiplexing along with gain control function generation information on generating a gain control function for performing the gain control and normalization coefficient information, the program causing the computer to execute the steps of:

adjusting a level of the signal by, for the coded code string, adding or substracting an integer value to/from the normalization coefficient information in the code string; and

modifying gain control function generation information according to the cutoff amount, if a subtracted amount of the normalization coefficient information is larger than the normalization coefficient information and the normalization coefficient information after subtraction is cut off at a minimum possible value thereof.