diff options
| -rw-r--r-- | src/limiter~.c | 149 |
1 files changed, 102 insertions, 47 deletions
diff --git a/src/limiter~.c b/src/limiter~.c index a0040f6..bd34744 100644 --- a/src/limiter~.c +++ b/src/limiter~.c @@ -2,9 +2,9 @@ * * zexy - implementation file * - * copyleft (c) IOhannes m zmölnig + * copyleft (c) IOhannes m zmölnig * - * 1999:forum::für::umläute:2004 + * 1999:forum::für::umläute:2004 * * institute of electronic music and acoustics (iem) * @@ -29,7 +29,7 @@ the limiter is based on Falkner's thesis "Entwicklung eines digitalen Stereo-limiters mit Hilfe des Signalprozessors DSP56001" pp.14 - 2108:forum::für::umläute:1999 all rights reserved and no warranties... + 2108:forum::für::umläute:1999 all rights reserved and no warranties... see GNU-license for details */ @@ -40,21 +40,47 @@ #include "zexy.h" +/* log2 */ #define LN2 .69314718056 -#define SINC1 .822462987 -#define SINC2 .404460777 -#define SINC3 -.188874003 -#define SINC4 -.143239449 -#define SINC5 .087796546 -#define SINC6 .06917082 -#define SINC7 -.041349667 -#define SINC8 -.030578954 -#define SINC9 .013226276 + + +/* hmm, where do these values come from exactly? + we are doing a 3* oversampling, so we need to calculate the samples that are +-1/3 off the current sample + sinc([13 10 7 4 1 -2 -5 -8 -11]/3) * window + window=cosine window + +*/ + +/* +#define SINC[4] .822462987 +#define SINC[3] .404460777 +#define SINC[5] -.188874003 +#define SINC[2] -.143239449 +#define SINC[6] .087796546 +#define SINC[1] .06917082 +#define SINC[7] -.041349667 +#define SINC[0] -.030578954 +#define SINC[8] .013226276 +*/ #define BUFSIZE 128 #define XTRASAMPS 9 #define TABLESIZE 512 /* compressor table */ +static t_sample SINC[9]; + +#define PI 3.1415926535897932384626433832795029L /* pi */ + +static void init_sinc(void) { + /* calculate the sinc (windowed with a cosine) */ + int i=0; + for(i=0; i<9; i++) { + long double t=(3.*i - 11.)/3.; + long double v=cos(t*PI/10.)*sin(PI*t)/(PI*t); + SINC[i]=v; + } +} + /* ------------------------------------------------------------------------------------ */ /* first define the structs... */ @@ -338,7 +364,7 @@ static void limiter_tilde_helper(t_limiter *x) "\n'set2 <limit2><htime2><rtime2>'\t: set crack-limiter"); break; case COMPRESS: - poststring("\n'ratio <compressratio>'\t\t: set compressratio (´0.5´ instead of ´1:2´)" + poststring("\n'ratio <compressratio>'\t\t: set compressratio (Ž0.5Ž instead of Ž1:2Ž)" "\n'treshold <treshold>'\t\t: set treshold of the compressor" "\n'compress <limit><treshold><ratio>'\t: set compressor" "\n..........note that <limit> is the same for COMPRESSOR and LIMITER.........."); @@ -380,43 +406,70 @@ static t_int *oversampling_maxima(t_int *w) t_sample last4, last3, last2, last1, sinccurrent, current, next1, next2, next3, next4; if (bp == ep) - { - vp[0] = bp[-9]; - vp[1] = bp[-8]; - vp[2] = bp[-7]; - vp[3] = bp[-6]; - vp[4] = bp[-5]; - vp[5] = bp[-4]; - vp[6] = bp[-3]; - vp[7] = bp[-2]; - vp[8] = bp[-1]; - - bp = vp + XTRASAMPS; - i -= bufsize - XTRASAMPS; - } - - os1= fabsf(SINC8 * (last4 = bp[-8]) + - SINC6 * (last3 = bp[-7]) + - SINC4 * (last2 = bp[-6]) + - SINC2 * (last1 = bp[-5]) + - (sinccurrent = SINC1 * (current = bp[-4])) + - SINC3 * (next1 = bp[-3]) + - SINC5 * (next2 = bp[-2]) + - SINC7 * (next3 = bp[-1]) + - SINC9 * (next4 = bp[0])); - - os2= fabsf(SINC8 * next4 + - SINC4 * next3 + - SINC6 * next2 + - SINC2 * next1 + - sinccurrent + - SINC3 * last1 + - SINC5 * last2 + - SINC7 * last3 + - SINC9 * last4); + { + vp[0] = bp[-9]; + vp[1] = bp[-8]; + vp[2] = bp[-7]; + vp[3] = bp[-6]; + vp[4] = bp[-5]; + vp[5] = bp[-4]; + vp[6] = bp[-3]; + vp[7] = bp[-2]; + vp[8] = bp[-1]; + + bp = vp + XTRASAMPS; + i -= bufsize - XTRASAMPS; + } + + + last4 = bp[-8]; + last3 = bp[-7]; + last2 = bp[-6]; + last1 = bp[-5]; + current = bp[-4]; + next1 = bp[-3]; + next2 = bp[-2]; + next3 = bp[-1]; + next4 = bp[0]; + + sinccurrent = SINC[4] * current; + + os1= fabsf(SINC[0] * last4 + + SINC[1] * last3 + + SINC[2] * last2 + + SINC[3] * last1 + + sinccurrent + + SINC[5] * next1 + + SINC[6] * next2 + + SINC[7] * next3 + + SINC[8] * next4); + + os2= fabsf(SINC[0] * next4 + + SINC[1] * next3 + + SINC[2] * next2 + + SINC[3] * next1 + + sinccurrent + + SINC[5] * last1 + + SINC[6] * last2 + + SINC[7] * last3 + + SINC[8] * last4); max = fabsf(current); +#if 0 + if(max>1. || os1>1. || os2>1.) + post("%f %f %f\t%f %f %f %f %f %f %f %f %f", max, os1, os2, + last4, + last3, + last2, + last1, + current, + next1, + next2, + next3, + next4 + ); +#endif if (max < os1) { max = os1; @@ -671,6 +724,8 @@ static void limiter_free(t_limiter *x) void limiter_tilde_setup(void) { + init_sinc(); + limiter_class = class_new(gensym("limiter~"), (t_newmethod)limiter_new, (t_method)limiter_free, sizeof(t_limiter), 0, A_GIMME, 0); |