1 /* libSoX Echo effect             August 24, 1998
30  *   echo gain-in gain-out delay-1 decay-1 [delay-2 decay-2 ... delay-n decay-n]
72         priv_t * echo = (priv_t *) effp->priv;  in sox_echo_getopts()  local
76         echo->num_delays = 0;  in sox_echo_getopts()
82         sscanf(argv[i++], "%f", &echo->in_gain);  in sox_echo_getopts()
83         sscanf(argv[i++], "%f", &echo->out_gain);  in sox_echo_getopts()
85                 if ( echo->num_delays >= MAX_ECHOS )  in sox_echo_getopts()
86                         lsx_fail("echo: to many delays, use less than %i delays",  in sox_echo_getopts()
89                 sscanf(argv[i++], "%f", &echo->delay[echo->num_delays]);  in sox_echo_getopts()
90                 sscanf(argv[i++], "%f", &echo->decay[echo->num_delays]);  in sox_echo_getopts()
91                 echo->num_delays++;  in sox_echo_getopts()
101         priv_t * echo = (priv_t *) effp->priv;  in sox_echo_start()  local
106         echo->maxsamples = 0;  in sox_echo_start()
107         if ( echo->in_gain < 0.0 )  in sox_echo_start()
109                 lsx_fail("echo: gain-in must be positive!");  in sox_echo_start()
112         if ( echo->in_gain > 1.0 )  in sox_echo_start()
114                 lsx_fail("echo: gain-in must be less than 1.0!");  in sox_echo_start()
117         if ( echo->out_gain < 0.0 )  in sox_echo_start()
119                 lsx_fail("echo: gain-in must be positive!");  in sox_echo_start()
122         for ( i = 0; i < echo->num_delays; i++ ) {  in sox_echo_start()
123                 echo->samples[i] = echo->delay[i] * effp->in_signal.rate / 1000.0;  in sox_echo_start()
124                 if ( echo->samples[i] < 1 )  in sox_echo_start()
126                     lsx_fail("echo: delay must be positive!");  in sox_echo_start()
129                 if ( echo->samples[i] > (ptrdiff_t)DELAY_BUFSIZ )  in sox_echo_start()
131                         lsx_fail("echo: delay must be less than %g seconds!",  in sox_echo_start()
135                 if ( echo->decay[i] < 0.0 )  in sox_echo_start()
137                     lsx_fail("echo: decay must be positive!" );  in sox_echo_start()
140                 if ( echo->decay[i] > 1.0 )  in sox_echo_start()
142                     lsx_fail("echo: decay must be less than 1.0!" );  in sox_echo_start()
145                 if ( echo->samples[i] > echo->maxsamples )  in sox_echo_start()
146                         echo->maxsamples = echo->samples[i];  in sox_echo_start()
148         echo->delay_buf = lsx_malloc(sizeof (double) * echo->maxsamples);  in sox_echo_start()
149         for ( j = 0; j < echo->maxsamples; ++j )  in sox_echo_start()
150                 echo->delay_buf[j] = 0.0;  in sox_echo_start()
153         for ( i = 0; i < echo->num_delays; i++ )  in sox_echo_start()
154                 sum_in_volume += echo->decay[i];  in sox_echo_start()
155         if ( sum_in_volume * echo->in_gain > 1.0 / echo->out_gain )  in sox_echo_start()
156                 lsx_warn("echo: warning >>> gain-out can cause saturation of output <<<");  in sox_echo_start()
157         echo->counter = 0;  in sox_echo_start()
158         echo->fade_out = echo->maxsamples;  in sox_echo_start()
172         priv_t * echo = (priv_t *) effp->priv;  in sox_echo_flow()  local
183                 d_out = d_in * echo->in_gain;  in sox_echo_flow()
184                 for ( j = 0; j < echo->num_delays; j++ ) {  in sox_echo_flow()
185                         d_out += echo->delay_buf[  in sox_echo_flow()
186 (echo->counter + echo->maxsamples - echo->samples[j]) % echo->maxsamples]  in sox_echo_flow()
187                         * echo->decay[j];  in sox_echo_flow()
190                 d_out = d_out * echo->out_gain;  in sox_echo_flow()
194                 echo->delay_buf[echo->counter] = d_in;  in sox_echo_flow()
196                 echo->counter = ( echo->counter + 1 ) % echo->maxsamples;  in sox_echo_flow()
207         priv_t * echo = (priv_t *) effp->priv;  in sox_echo_drain()  local
215         while ( ( done < *osamp ) && ( done < echo->fade_out ) ) {  in sox_echo_drain()
218                 for ( j = 0; j < echo->num_delays; j++ ) {  in sox_echo_drain()
219                         d_out += echo->delay_buf[  in sox_echo_drain()
220 (echo->counter + echo->maxsamples - echo->samples[j]) % echo->maxsamples]  in sox_echo_drain()
221                         * echo->decay[j];  in sox_echo_drain()
224                 d_out = d_out * echo->out_gain;  in sox_echo_drain()
228                 echo->delay_buf[echo->counter] = d_in;  in sox_echo_drain()
230                 echo->counter = ( echo->counter + 1 ) % echo->maxsamples;  in sox_echo_drain()
232                 echo->fade_out--;  in sox_echo_drain()
236         if (echo->fade_out == 0)  in sox_echo_drain()
244         priv_t * echo = (priv_t *) effp->priv;  in sox_echo_stop()  local
246         free(echo->delay_buf);  in sox_echo_stop()
247         echo->delay_buf = NULL;  in sox_echo_stop()
252   "echo",