/* libSoX Echo effect             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. * * * 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 ) */ #include "sox_i.h" #include <stdlib.h> /* Harmless, and prototypes atof() etc. --dgc */ #define DELAY_BUFSIZ ( 50 * 50U * 1024 )#define MAX_ECHOS 7     /* 24 bit x ( 1 + MAX_ECHOS ) = */                        /* 24 bit x 8 = 32 bit !!!      */ /* Private data for SKEL file */typedef struct {        int     counter;        int     num_delays;        double  *delay_buf;        float   in_gain, out_gain;        float   delay[MAX_ECHOS], decay[MAX_ECHOS];        ptrdiff_t samples[MAX_ECHOS], maxsamples;        size_t fade_out;} priv_t; /* Private data for SKEL file */  /* * Process options */static int sox_echo_getopts(sox_effect_t * effp, int argc, char **argv){        priv_t * echo = (priv_t *) effp->priv;        int i;   --argc, ++argv;        echo->num_delays = 0;         if ((argc < 4) || (argc % 2))          return lsx_usage(effp);         i = 0;        sscanf(argv[i++], "%f", &echo->in_gain);        sscanf(argv[i++], "%f", &echo->out_gain);        while (i < argc) {                if ( echo->num_delays >= MAX_ECHOS )                        lsx_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 (SOX_SUCCESS);} /* * Prepare for processing. */static int sox_echo_start(sox_effect_t * effp){        priv_t * echo = (priv_t *) effp->priv;        int i;        float sum_in_volume;        long j;         echo->maxsamples = 0;        if ( echo->in_gain < 0.0 )        {                lsx_fail("echo: gain-in must be positive!");                return (SOX_EOF);        }        if ( echo->in_gain > 1.0 )        {                lsx_fail("echo: gain-in must be less than 1.0!");                return (SOX_EOF);        }        if ( echo->out_gain < 0.0 )        {                lsx_fail("echo: gain-in must be positive!");                return (SOX_EOF);        }        for ( i = 0; i < echo->num_delays; i++ ) {                echo->samples[i] = echo->delay[i] * effp->in_signal.rate / 1000.0;                if ( echo->samples[i] < 1 )                {                    lsx_fail("echo: delay must be positive!");                    return (SOX_EOF);                }                if ( echo->samples[i] > (ptrdiff_t)DELAY_BUFSIZ )                {                        lsx_fail("echo: delay must be less than %g seconds!",                                DELAY_BUFSIZ / effp->in_signal.rate );                        return (SOX_EOF);                }                if ( echo->decay[i] < 0.0 )                {                    lsx_fail("echo: decay must be positive!" );                    return (SOX_EOF);                }                if ( echo->decay[i] > 1.0 )                {                    lsx_fail("echo: decay must be less than 1.0!" );                    return (SOX_EOF);                }                if ( echo->samples[i] > echo->maxsamples )                        echo->maxsamples = echo->samples[i];        }        echo->delay_buf = lsx_malloc(sizeof (double) * echo->maxsamples);        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 )                lsx_warn("echo: warning >>> gain-out can cause saturation of output <<<");        echo->counter = 0;        echo->fade_out = echo->maxsamples;   effp->out_signal.length = SOX_UNKNOWN_LEN; /* TODO: calculate actual length */         return (SOX_SUCCESS);} /* * Processed signed long samples from ibuf to obuf. * Return number of samples processed. */static int sox_echo_flow(sox_effect_t * effp, const sox_sample_t *ibuf, sox_sample_t *obuf,                 size_t *isamp, size_t *osamp){        priv_t * echo = (priv_t *) effp->priv;        int j;        double d_in, d_out;        sox_sample_t out;        size_t len = min(*isamp, *osamp);        *isamp = *osamp = len;         while (len--) {                /* 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 = SOX_24BIT_CLIP_COUNT((sox_sample_t) d_out, effp->clips);                *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 (SOX_SUCCESS);} /* * Drain out reverb lines. */static int sox_echo_drain(sox_effect_t * effp, sox_sample_t *obuf, size_t *osamp){        priv_t * echo = (priv_t *) effp->priv;        double d_in, d_out;        sox_sample_t out;        int j;        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 = SOX_24BIT_CLIP_COUNT((sox_sample_t) d_out, effp->clips);                *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;        if (echo->fade_out == 0)            return SOX_EOF;        else            return SOX_SUCCESS;} static int sox_echo_stop(sox_effect_t * effp){        priv_t * echo = (priv_t *) effp->priv;         free(echo->delay_buf);        echo->delay_buf = NULL;        return (SOX_SUCCESS);} static sox_effect_handler_t sox_echo_effect = {  "echo",  "gain-in gain-out delay decay [ delay decay ... ]",  SOX_EFF_LENGTH | SOX_EFF_GAIN,  sox_echo_getopts,  sox_echo_start,  sox_echo_flow,  sox_echo_drain,  sox_echo_stop,  NULL, sizeof(priv_t)}; const sox_effect_handler_t *lsx_echo_effect_fn(void){    return &sox_echo_effect;}