User`s guide

IDCT
5-228
5IDCT
Purpose Compute the IDCT of the input.
Library Transforms
Description The IDCT block computes the inverse discrete cosine transform (IDCT) of each
channel in the M-by-N input matrix,
u.
y = idct(u) % Equivalent MATLAB code
For both sample-based and frame-based inputs, the block assumes that each
input column is a frame containing M consecutive samples from an
independent channel. The frame size, M, must be a power-of-two. To work with
other frame sizes, use the Zero Pad block to pad or truncate the frame size to a
power-of-two length.
The output is an M-by-N matrix whose lth column contains the length-M IDCT
of the corresponding input column.
where
The output is always frame-based, and the output sample rate and data type
(real/complex) are the same as those of the input.
For convenience, length-M 1-D vector inputs and sample-based length-M row
vector inputs are processed as single channels (i.e., as M-by-1 column vectors),
and the output has the same dimension as the input.
yml,() wk()ukl,()
π 2m 1–()k 1–()
2M
--------------------------------------------
, mcos
k 1=
M
∑
1 … M,,==
wk()
1
M
---------
, k 1=
2
M
----- , 2 kM≤≤
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