Patent ID: 6721708
Filing Date: 2004-04-13
Classification: G06F

Abstract:
A method of performing an inverse modified discrete cosine transform (IMDCT) on at least a block of N/4 spectral coefficients representing an information signal in the frequency domain, the IMDCT providing an IMDCT output including at least one block of processed samples in the time domain, the method comprising:converting spectral coefficients in the block of spectral coefficients to provide a block of N/4 frequency domain processed complex samples, u(n), where the coefficients comprises N/4 spectral coefficients, are represented as X and: u&af;(n)=&Sum;k=0N/4-1&it;â€ƒ&it;-(X&af;(N/2-2&it;k-1)+j&it;â€ƒ&it;X&af;(2&it;k))&it;&ee;j2Ï€&it;â€ƒ&it;k&af;(n+1/4)/(N/4);&it;â€ƒwhere&it;â€ƒ&it;n=0,1,â€¦&it;â€ƒ&it;N/4-1;andprocessing the block of N/4 frequency domain processed complex samples into the block of processed samples in the time domain by at least multiplying each sample by ej2Î (n+Â¼)/N.