Hi all.
I'm an undergraduate computer engineer at UOW.
For a project I have to manipulate the subbanded mdct
transformed sample values when encoding in mp3 (layer3).
I have been trying to understand the code dist10, but
unfortunately without the standard, I can't seem to
make much sense of it. I would appreciate _ANY_ help.
Unfortuantely I seem to be going nowhere on my limited
resources.
For the Encoder, I am getting the values of xr[2][2][576]
after the function mdct_sub() in musicin.c,
where the first array index is the channel and the second and
third represent the 1152 audio samples.
For the Decoder, I assume I have to fill up hybridIn[32][18]
just before the hybrid synthesis, function III_hybrid() in
musicout.c, which performs the inverse mdct as well.
Obviously 'hybridIn[32][18]' and 'xr[2][2][576]' are not
equivalent.
--> Are the values of 'hybridIn' the SAME (with no extra manipulations)
as each single channel of 'xr'? That is, on the first loop,
'hybridIn' is equal to 'xr[0]' and on the second loop of the
channel for a stereo signal, 'hybridIn' is equal to 'xr[1]' ???
(I have tried to compare the values of 'xr' and 'hybridIn',
but they're not the same - obviously due to the perceptual masking.)
--> If I have a mono audio signal, do I only worry about xr[0]??
--> Or am I totally wrong?
I'd appreciate _ANY_ and _ALL_ help.
sincerely,
Gabriella
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