Relation between IMDCT and IFFT

Hi all,

Could you please explain the relation between IMDCT and IFFT?

Thanks in Advance,
Jebaraj S.Peter. Start a New Thread

In fact, MDCT uses cosine transation, but FFT uses sine transation.MDCT can be implemneted by FFT.

2009-04-04 20:30:53"peter jebaraj" д
Hi all,

Could you please explain the relation between IMDCT and IFFT?

Thanks in Advance,
Jebaraj S.Peter.

_____________________________________ Start a New Thread

Dear Jebaraj,

FFT is an efficient algorithm to compute DFT & its inverse. A DFT decomposes a sequence of values into components of different frequencies.

MDCT is based on DCT4 with property of overlapping.

DCT expresses a sequence of finitely many data points in terms of a sum of cosine functions oscillating at different frequencies. For compression, it turns out that cosine functions are much more efficient (fewer are needed to approximate a typical signal). Essentially it is similar to DFT but using only real numbers. DCTs are equivalent to DFTs of roughly twice the length, operating on real data with even symmetry. There are eight standard DCT variants, of
which four are common.

MDCT is designed to be performed on consecutive blocks of a larger
dataset, where subsequent blocks are overlapped so that the last half
of one block coincides with the first half of the next block.

It is possible to compute MDCT recursively factorizing the computation, as in FFT.

Regards,
abhishek

--- On Sat, 4/4/09, peter jebaraj wrote:

From: peter jebaraj
Subject: [audiodsp] Relation between IMDCT and IFFT
To: a...
Received: Saturday, 4 April, 2009, 6:00 PM


Hi all,

Could you please explain the relation between IMDCT and IFFT?

Thanks in Advance,
Jebaraj S.Peter.



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