MDCT/IMDCT with KBD Window 2015-01-04 20:37:04 I search C/C++ sources for both MDCT encoder and IMDCT decoder with KBD Window. I hear, this KBD window is used in AAC, but is difficult to find sources simultaneously for encoder and decoder. I want look at function restore overlapping signal after IMDCT.IN www.fftw.org are DFT algorithms in C (one MDCT is in Ocaml). How prepare MDCT data for calling FFT?

MDCT/IMDCT with KBD Window Reply #2 – 2015-01-05 08:37:18 Here is: * Fast (I)MDCT Implementation using (I)FFT ((Inverse) Fast Fourier Transform) * and consists of three steps: pre-(I)FFT complex multiplication, complex * (I)FFT, post-(I)FFT complex multiplication, this mean that function faad_mdct works in both directions? This is only decoder, how use it in encodng?

MDCT/IMDCT with KBD Window Reply #3 – 2015-01-05 13:39:55 Quote from: Borneq on 2015-01-05 08:37:18this mean that function faad_mdct works in both directions?No, there is faad_imdct in mdct.c as well. The actual overlap-add routines are in filtbank.c. The direct MDCT (faad_mdct) is used for LTP decoding.QuoteThis is only decoder, how use it in encodng?FAAD is the decoder, FAAC is the encoder. If you're interested in encoding, look at the FAAC sources. The MDCT algorithm itself seems to be the same, though.

MDCT/IMDCT with KBD Window Reply #4 – 2015-01-09 17:57:30 How call LTP decoding? I open faad\frontend\faad.sln and build;when I decode file to wav, faad_imdct is called, but how call faad_mdct?This is for function filter_bank_ltp: #ifdef LTP_DEC /* only works for LTP -> no overlapping, no short blocks */In FAAC, in filtbank.c is function MDCT - is the same as faad_mdct ? void faad_mdct(mdct_info *mdct, real_t *X_in, real_t *X_out)static void MDCT( FFT_Tables *fft_tables, double *data, int N ) Last Edit: 2015-01-09 18:05:13 by Borneq

MDCT/IMDCT with KBD Window Reply #5 – 2015-01-09 18:18:15 Quote from: Borneq on 2015-01-09 17:57:30How call LTP decoding?LTP is a dead format, so there is no need to worry about it.