Encoding method, encoder, periodic feature amount determination method, periodic feature amount determination apparatus, program and recording medium
First Claim
1. A computer-implemented encoding method for encoding a sample string in a frequency domain that is derived from an audio signal in frames, executing on a processor, the method comprising:
- a step of receiving the sample string of the audio signal in the time-domain;
a step of transforming the audio signal in the time-domain to the frequency-domain;
an interval determination step of determining an interval T between samples from a set S of candidates for the interval T, the interval T corresponding to a periodicity of the audio signal or to an integer multiple of a fundamental frequency of the audio signal;
a side information generating step of encoding the interval T determined at the interval determination step to obtain side information;
outputting the side information to a decoder;
a sample string encoding step of encoding a rearranged sample to obtain a code string, the rearranged sample string(1) including all of the samples in the sample string, and(2) being a sample string in which at least some of the samples are rearranged so that all or some of one or a plurality of successive samples including a sample corresponding to the periodicity or the fundamental frequency of the audio signal in the sample string and one or a plurality of successive samples including a sample corresponding to an integer multiple of the periodicity or the fundamental frequency of the audio signal in the sample string are gathered together into a cluster on the basis of the interval T determined by the interval determination step;
wherein the interval determination step determines the interval T from a set S of candidates for the interval T, the set S being made up of Y candidates among Z candidates for the interval T, the Y candidates including Z2 candidates selected without depending on a previous candidate for the interval T corresponding to a periodicity of the audio signal or to an integer multiple of a fundamental frequency of the audio signal, the previous candidate subjected to the interval determination step in a previous frame a predetermined number of frames before the current frame and including the previous candidate subjected to the interval determination step in the previous frame the predetermined number of frames before the current frame, the Z candidates being representable with the side information, where Z2<
Z and Y<
Z; and
outputting the code string to the decoder, wherein the code string has a compressed amount of data compared to the received sample string of the audio signal, and the decoder is configured to reproduce a sample string of an audio signal in the time-domain based on the code string and the side information.
1 Assignment
0 Petitions
Accused Products
Abstract
An encoding technique encoding a sound signal at a low bit rate with reduced processing. The technique includes: an interval determination determining an interval T between samples corresponding to periodicity of an audio signal or an integer multiple of a fundamental frequency of the audio signal from a set S of candidates for the interval T; and a side information generating encoding the determined interval T to obtain side information. The interval determining determines the interval T from a set S of Y candidates (Y<Z) including Z2 candidates (Z2<Z) selected from among Z candidates for the interval T representable with the side information without depending on a candidate subjected to the interval determination in a previous frame a predetermined number of frames before the current frame and including a candidate subjected to the interval determination in the previous frame the predetermined number of frames before the current frame.
21 Citations
22 Claims
-
1. A computer-implemented encoding method for encoding a sample string in a frequency domain that is derived from an audio signal in frames, executing on a processor, the method comprising:
-
a step of receiving the sample string of the audio signal in the time-domain; a step of transforming the audio signal in the time-domain to the frequency-domain; an interval determination step of determining an interval T between samples from a set S of candidates for the interval T, the interval T corresponding to a periodicity of the audio signal or to an integer multiple of a fundamental frequency of the audio signal; a side information generating step of encoding the interval T determined at the interval determination step to obtain side information; outputting the side information to a decoder; a sample string encoding step of encoding a rearranged sample to obtain a code string, the rearranged sample string (1) including all of the samples in the sample string, and (2) being a sample string in which at least some of the samples are rearranged so that all or some of one or a plurality of successive samples including a sample corresponding to the periodicity or the fundamental frequency of the audio signal in the sample string and one or a plurality of successive samples including a sample corresponding to an integer multiple of the periodicity or the fundamental frequency of the audio signal in the sample string are gathered together into a cluster on the basis of the interval T determined by the interval determination step; wherein the interval determination step determines the interval T from a set S of candidates for the interval T, the set S being made up of Y candidates among Z candidates for the interval T, the Y candidates including Z2 candidates selected without depending on a previous candidate for the interval T corresponding to a periodicity of the audio signal or to an integer multiple of a fundamental frequency of the audio signal, the previous candidate subjected to the interval determination step in a previous frame a predetermined number of frames before the current frame and including the previous candidate subjected to the interval determination step in the previous frame the predetermined number of frames before the current frame, the Z candidates being representable with the side information, where Z2<
Z and Y<
Z; andoutputting the code string to the decoder, wherein the code string has a compressed amount of data compared to the received sample string of the audio signal, and the decoder is configured to reproduce a sample string of an audio signal in the time-domain based on the code string and the side information. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 22)
-
-
14. A computer-implemented method for determining a periodic feature amount of an input audio signal in frames, executing on a processor, the method comprising:
-
a step of receiving the audio signal in the time-domain; a step of transforming the audio signal in the time-domain to the frequency-domain; a periodic feature amount determination step of determining a periodic feature amount of the audio signal from a set of candidates for the periodic feature amount of the audio signal on a frame-by-frame basis; outputting the periodic feature amount of the audio signal; a side information generating step of encoding the periodic feature amount obtained at the periodic feature amount determination step to obtain side information; and outputting the side information, wherein the periodic feature amount determination step determines a periodic feature amount of the audio signal from a set S of candidates for the periodic feature amount of the audio signal, the set S being made up of Y candidates among Z candidates for the periodic feature amount of the audio signal, the Y candidates including Z2 candidates selected without depending on a previous candidate for the periodic feature amount of the audio signal, the previous candidate subjected to the periodic feature amount determination step in a previous frame a predetermined number of frames before the current frame and including the previous candidate subjected to the periodic feature amount determination step in the previous frame the predetermined number of frames before the current frame, the Z candidates being representable with the side information, where Z2<
Z and Y<
Z;wherein the periodic feature amount of the audio signal is a fundamental frequency or pitch period of the audio signal, wherein the side information is configured to be outputted to a decoder along with a code string, the code string being generated by encoding a rearranged sample of the audio signal and having a compressed amount of data compared to the received sample string of the audio signal, and the decoder is configured to reproduce a sample string of an audio signal in the time-domain based on the code string and the side information. - View Dependent Claims (15, 16, 17, 18)
-
-
19. A encoder encoding a sample string in a frequency domain that is derived from an audio signal in frames, the encoder comprising a processor configured to act as:
-
a frequency-domain transform unit that receives the sample string of the audio signal in the time domain and transforms the audio signal in the time-domain to the frequency-domain; an interval determination unit that determines an interval T between samples from a set S of candidates for the interval T, the interval T corresponding to a periodicity of the audio signal or to an integer multiple of a fundamental frequency of the audio signal; a side information generating unit that encodes the interval T determined by the interval determination unit to obtain side information and outputs the side information to a decoder; a sample string encoding unit that encodes a rearranged sample string to obtain a code string and outputs the code string to the decoder, the rearranged sample string (1) including all of the samples in the sample string, and (2) being a sample string in which at least some of the samples are rearranged so that all or some of one or a plurality of successive samples including a sample corresponding to the periodicity or the fundamental frequency of the audio signal in the sample string and one or a plurality of successive samples including a sample corresponding to an integer multiple of the periodicity or the fundamental frequency of the audio signal in the sample string are gathered together into a cluster on the basis of the interval T determined by the interval determination unit; wherein the interval determination unit determines the interval T from a set S of candidates for the interval T, the set S being made up of Y candidates among Z candidates for the interval T, the Y candidates including Z2 candidates selected without depending on a previous candidate for the interval T corresponding to a periodicity of the audio signal or to an integer multiple of a fundamental frequency of the audio signal, the previous candidate subjected to processing by the interval determination unit in a previous frame a predetermined number of frames before the current frame and including the previous candidate subjected to the processing by the interval determination unit in the previous frame the predetermined number of frames before the current frame, the Z candidates being representable with the side information, where Z2<
Z and Y<
Z,wherein the code string and the side information have a compressed amount of data compared to the received sample string of the audio signal, and the decoder is configured to reproduce a sample string of an audio signal in the time-domain based on the code string and the side information. - View Dependent Claims (20)
-
-
21. A periodic feature amount determination apparatus determining a periodic feature amount of an input audio signal in frames, the apparatus comprising a processor configured to act as:
-
a frequency-domain transform unit that receives the sample string of the audio signal in the time domain and transforms the audio signal in the time-domain to the frequency-domain; a periodic feature amount determination unit that determines a periodic feature amount of the audio signal from a set of candidates for the periodic feature amount on a frame-by-frame basis and outputs the periodic feature amount of the audio signal; and a side information generating unit that encodes the periodic feature amount obtained at the periodic feature amount determination unit to obtain side information and outputs the side information; wherein the periodic feature amount determination unit determines a periodic feature amount of the audio signal from a set S of candidates for the periodic feature amount of the audio signal, the set S being made up of Y candidates among Z candidates for the periodic feature amount of the audio signal, the Y candidates including Z2 candidates selected without depending on a previous candidate for the periodic feature amount of the audio signal, the previous candidate subjected to the periodic feature amount determination unit in a previous frame a predetermined number of frames before the current frame and including the previous candidate subjected to the periodic feature amount determination unit in the previous frame the predetermined number of frames before the current frame, the Z candidates being representable with the side information, where Z2<
Z and Y<
Z;wherein the periodic feature amount of the audio signal is a fundamental frequency or pitch period of the audio signal, wherein the side information is configured to be outputted to a decoder along with a code string, the code string being generated by encoding a rearranged sample of the audio signal and having a compressed amount of data compared to the received sample string of the audio signal, and the decoder is configured to reproduce a sample string of an audio signal in the time-domain based on the code string and the side information.
-
Specification