Signal processing method and data processing method and apparatus

A frequency-domain to time-domain signal processing method, comprising:

• twiddling, by a digital signal processor, frequency-domain data;
• pre-rotating, by a digital signal processor, the twiddled data by using a rotation factor c·WNk+0.5;
• performing, by a digital signal processor, a discrete Fourier transform (DFT) of N/4 points on the pre-rotated data;
• post-rotating, by a digital signal processor, the data transformed by the DFT by using a rotation factor d·WNn+0.5;
• and
• post-processing, by a digital signal processor, the post-rotated data to obtain time-domain data;
• where:
• c and d are constants, N is twice the length of the frequency-domain data,
• W
• N
• =
• ⅇ
• -
• j
• ⁢
• 2
• ⁢
• π
• N
• ,
• ⁢
• W
• N
• n
• +
• 0.5
• =
• ⅇ
• -
• j
• ⁢
• 2
• ⁢
• π
• N
• ⁢
• (
• n
• +
• 0.5
• )
• ,
• ⁢
• W
• N
• k
• +
• 0.5
• =
• ⅇ
• -
• j
• ⁢
• 2
• ⁢
• π
• N
• ⁢
• (
• k
• +
• 0.5
• )
• ,
• n=0, . . . , N/4−1, and k=0, . . . , N/4−1.

A data processing method, comprising:

• performing, by a digital signal processor, P-point discrete Fourier transform (DFT) for Q times on data based on an address table;
• and
• performing, by a digital signal processor, Q-point DFT for P times on the data obtained after the P-point DFT for Q times based on the address table;
• wherein:
• P and Q are coprime positive integers;
• the address table is <K1×n1+K2×n2>M, where M is the length of the address table and M=P×Q, n1=0, . . . , P−1, n2=0, . . . , Q−1, and K1 and K2 are coprime positive integers that satisfy <K1K2>M=0.

A frequency-domain to time-domain signal processing apparatus in super wideband digital audio encoding, comprising:

• a twiddling unit, configured on a digital signal processor to Twiddle frequency-domain data;
• a second pre-rotating unit, configured on a digital signal processor to pre-rotate the data obtained by the twiddling unit by using a rotation factor c·WNk+0.5;
• a second Fourier transforming unit, configured on a digital signal processor to perform a discrete Fourier transform (DFT) of N/4 points on the data processed by the second pre-rotating unit;
• a third post-rotating unit, configured on a digital signal processor to post-rotate the data transformed by the second Fourier transforming unit by using a rotation factor d·WNn+0.5;
• and
• a post-processing unit, configured on a digital signal processor to post-process the data processed by the third post-rotating unit to obtain time-domain data;
• where:
• c and d are constants, N is twice the length of the frequency-domain data,
• W
• N
• n
• +
• 0.5
• =
• ⅇ
• -
• j
• ⁢
• 2
• ⁢
• π
• N
• ⁢
• (
• n
• +
• 0.5
• )
• ,
• ⁢
• W
• N
• k
• +
• 0.5
• =
• ⅇ
• -
• j
• ⁢
• 2
• ⁢
• π
• N
• ⁢
• (
• k
• +
• 0.5
• )
• ,
• n=0, . . . , N/4−1 and k=0, . . . , N/4−1.

A data processing apparatus in super wideband digital audio encoding, comprising:

• an address table unit, configured on a digital signal processor to create or store an address table;
• a P-point Q times transforming unit, a fifth transforming unit, configured on a digital signal processor to perform P-point discrete Fourier transform (DFT) for Q times on the data based on the address table created or stored by the address table unit;
• and
• a Q-point P times transforming unit, a sixth transforming unit, configured on a digital signal processor to perform Q-point DFT for P times on the data transformed by a fifth transforming unit based on the address table created or stored by the address table unit;
• wherein:
• P and Q are coprime positive integers;
• the address table is <K1×n1+K2×n2>M, where M is the length of the address table and M=P×Q, n1=0, . . . , P−1, n2=0, . . . , Q−1 and K1 and K2 are coprime positive integers that satisfy <K1K2>M=0.