ref: 49be44ccb713c2a5373751861efcf2adc0958c5d
dir: /src/echo.c/
/* * August 24, 1998 * Copyright (C) 1998 Juergen Mueller And Sundry Contributors * This source code is freely redistributable and may be used for * any purpose. This copyright notice must be maintained. * Juergen Mueller And Sundry Contributors are not responsible for * the consequences of using this software. */ /* * This is the "echo.c" while the old "echo.c" from version 12 moves to * "reverb.c" satisfying the defintions made in the Guitar FX FAQ. * * * Echo effect for dsp. * * Flow diagram scheme for n delays ( 1 <= n <= MAX_ECHOS ): * * * gain-in ___ * ibuff -----------+------------------------------------------>| | * | _________ | | * | | | * decay 1 | | * +----->| delay 1 |------------------------->| | * | |_________| | | * | _________ | + | * | | | * decay 2 | | * +---------->| delay 2 |-------------------->| | * | |_________| | | * : _________ | | * | | | * decay n | | * +--------------->| delay n |--------------->|___| * |_________| | * | * gain-out * | * +----->obuff * * Usage: * echo gain-in gain-out delay-1 decay-1 [delay-2 decay-2 ... delay-n decay-n] * * Where: * gain-in, decay-1 ... decay-n : 0.0 ... 1.0 volume * gain-out : 0.0 ... volume * delay-1 ... delay-n : > 0.0 msec * * Note: * when decay is close to 1.0, the samples can begin clipping and the output * can saturate! * * Hint: * 1 / out-gain > gain-in ( 1 + decay-1 + ... + decay-n ) * */ /* * Sound Tools reverb effect file. */ #include <stdlib.h> /* Harmless, and prototypes atof() etc. --dgc */ #include <math.h> #include "st_i.h" #define DELAY_BUFSIZ ( 50L * ST_MAXRATE ) #define MAX_ECHOS 7 /* 24 bit x ( 1 + MAX_ECHOS ) = */ /* 24 bit x 8 = 32 bit !!! */ /* Private data for SKEL file */ typedef struct echostuff { int counter; int num_delays; double *delay_buf; float in_gain, out_gain; float delay[MAX_ECHOS], decay[MAX_ECHOS]; st_ssize_t samples[MAX_ECHOS], maxsamples; st_size_t fade_out; } *echo_t; /* Private data for SKEL file */ /* * Process options */ int st_echo_getopts(eff_t effp, int n, char **argv) { echo_t echo = (echo_t) effp->priv; int i; echo->num_delays = 0; if ((n < 4) || (n % 2)) { st_fail("Usage: echo gain-in gain-out delay decay [ delay decay ... ]"); return (ST_EOF); } i = 0; sscanf(argv[i++], "%f", &echo->in_gain); sscanf(argv[i++], "%f", &echo->out_gain); while (i < n) { if ( echo->num_delays >= MAX_ECHOS ) st_fail("echo: to many delays, use less than %i delays", MAX_ECHOS); /* Linux bug and it's cleaner. */ sscanf(argv[i++], "%f", &echo->delay[echo->num_delays]); sscanf(argv[i++], "%f", &echo->decay[echo->num_delays]); echo->num_delays++; } return (ST_SUCCESS); } /* * Prepare for processing. */ int st_echo_start(eff_t effp) { echo_t echo = (echo_t) effp->priv; int i; float sum_in_volume; long j; echo->maxsamples = 0L; if ( echo->in_gain < 0.0 ) { st_fail("echo: gain-in must be positive!\n"); return (ST_EOF); } if ( echo->in_gain > 1.0 ) { st_fail("echo: gain-in must be less than 1.0!\n"); return (ST_EOF); } if ( echo->out_gain < 0.0 ) { st_fail("echo: gain-in must be positive!\n"); return (ST_EOF); } for ( i = 0; i < echo->num_delays; i++ ) { echo->samples[i] = echo->delay[i] * effp->ininfo.rate / 1000.0; if ( echo->samples[i] < 1 ) { st_fail("echo: delay must be positive!\n"); return (ST_EOF); } if ( echo->samples[i] > DELAY_BUFSIZ ) { st_fail("echo: delay must be less than %g seconds!\n", DELAY_BUFSIZ / (float) effp->ininfo.rate ); return (ST_EOF); } if ( echo->decay[i] < 0.0 ) { st_fail("echo: decay must be positive!\n" ); return (ST_EOF); } if ( echo->decay[i] > 1.0 ) { st_fail("echo: decay must be less than 1.0!\n" ); return (ST_EOF); } if ( echo->samples[i] > echo->maxsamples ) echo->maxsamples = echo->samples[i]; } if (! (echo->delay_buf = (double *) malloc(sizeof (double) * echo->maxsamples))) { st_fail("echo: Cannot malloc %d bytes!\n", sizeof(long) * echo->maxsamples); return (ST_EOF); } for ( j = 0; j < echo->maxsamples; ++j ) echo->delay_buf[j] = 0.0; /* Be nice and check the hint with warning, if... */ sum_in_volume = 1.0; for ( i = 0; i < echo->num_delays; i++ ) sum_in_volume += echo->decay[i]; if ( sum_in_volume * echo->in_gain > 1.0 / echo->out_gain ) st_warn("echo: warning >>> gain-out can cause saturation of output <<<"); echo->counter = 0; echo->fade_out = echo->maxsamples; return (ST_SUCCESS); } /* * Processed signed long samples from ibuf to obuf. * Return number of samples processed. */ int st_echo_flow(eff_t effp, st_sample_t *ibuf, st_sample_t *obuf, st_size_t *isamp, st_size_t *osamp) { echo_t echo = (echo_t) effp->priv; int len, done; int j; double d_in, d_out; st_sample_t out; len = ((*isamp > *osamp) ? *osamp : *isamp); for(done = 0; done < len; done++) { /* Store delays as 24-bit signed longs */ d_in = (double) *ibuf++ / 256; /* Compute output first */ d_out = d_in * echo->in_gain; for ( j = 0; j < echo->num_delays; j++ ) { d_out += echo->delay_buf[ (echo->counter + echo->maxsamples - echo->samples[j]) % echo->maxsamples] * echo->decay[j]; } /* Adjust the output volume and size to 24 bit */ d_out = d_out * echo->out_gain; out = st_clip24((st_sample_t) d_out); *obuf++ = out * 256; /* Store input in delay buffer */ echo->delay_buf[echo->counter] = d_in; /* Adjust the counter */ echo->counter = ( echo->counter + 1 ) % echo->maxsamples; } /* processed all samples */ return (ST_SUCCESS); } /* * Drain out reverb lines. */ int st_echo_drain(eff_t effp, st_sample_t *obuf, st_size_t *osamp) { echo_t echo = (echo_t) effp->priv; double d_in, d_out; st_sample_t out; int j; st_size_t done; done = 0; /* drain out delay samples */ while ( ( done < *osamp ) && ( done < echo->fade_out ) ) { d_in = 0; d_out = 0; for ( j = 0; j < echo->num_delays; j++ ) { d_out += echo->delay_buf[ (echo->counter + echo->maxsamples - echo->samples[j]) % echo->maxsamples] * echo->decay[j]; } /* Adjust the output volume and size to 24 bit */ d_out = d_out * echo->out_gain; out = st_clip24((st_sample_t) d_out); *obuf++ = out * 256; /* Store input in delay buffer */ echo->delay_buf[echo->counter] = d_in; /* Adjust the counters */ echo->counter = ( echo->counter + 1 ) % echo->maxsamples; done++; echo->fade_out--; }; /* samples played, it remains */ *osamp = done; return (ST_SUCCESS); } /* * Clean up reverb effect. */ int st_echo_stop(eff_t effp) { echo_t echo = (echo_t) effp->priv; free((char *) echo->delay_buf); echo->delay_buf = (double *) -1; /* guaranteed core dump */ return (ST_SUCCESS); }