Displaying 2 results from an estimated 2 matches for "trigbit".
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trigbits
2002 Aug 01
2
mdct.h - PI1_8, PI2_8 etc.
In vorbis/lib/mdct.h the following are defined:
for integer:
#define TRIGBITS 14
#define cPI3_8 6270
#define cPI2_8 11585
#define cPI1_8 15137
#define FLOAT_CONV(x) ((int)((x)*(1<<TRIGBITS)+.5))
for floats:
#define cPI3_8 .38268343236508977175F
#define cPI2_8 .70710678118654752441F
#define cPI1_8 .92387953251128675613F
#define FLOAT_CONV(x) = x
Could someone explain...
2002 Aug 21
1
MDCT input and output data blocks
...in data obtained from the MDCT, is changed
when setting #define MDCT_INTEGERIZED
For instance, the trig array, for a size 256 window begins
1.000000
0.000000
0.998795
-0.049068
0.995185
-0.098017
if INTEGERIZED is set, then it begins
16384
0
16364
-803
16305
-1605
which is simply a left shift of TRIGBITS (14 in this case), or a
multiply by 16384 if you prefer to think of it like that. So far, so
good.
However if I display the data blocks (*in and *out) before and after
transformation:
mapping0.c: mdct_backward(b->transform[vb->W][0],pcm,pcm);
in floats:
'in' begins (before tr...