ref: 6473d74a9108c394dc2983f7364ae2f871900cd5
dir: /src/contrast.c/
/* libSoX effect: Contrast Enhancement (c) 2008 robs@users.sourceforge.net
*
* This library is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 2.1 of the License, or (at
* your option) any later version.
*
* This library is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
* General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this library; if not, write to the Free Software Foundation,
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "sox_i.h"
typedef struct {double contrast;} priv_t;
static int create(sox_effect_t * effp, int argc, char * * argv)
{
priv_t * p = (priv_t *)effp->priv;
p->contrast = 75;
--argc, ++argv;
do {NUMERIC_PARAMETER(contrast, 0, 100)} while (0);
p->contrast /= 750; /* shift range to 0 to 0.1333, default 0.1 */
return argc? lsx_usage(effp) : SOX_SUCCESS;
}
static int flow(sox_effect_t * effp, const sox_sample_t * ibuf,
sox_sample_t * obuf, size_t * isamp, size_t * osamp)
{
priv_t * p = (priv_t *)effp->priv;
size_t len = *isamp = *osamp = min(*isamp, *osamp);
while (len--) {
double d = *ibuf++ * (-M_PI_2 / SOX_SAMPLE_MIN);
*obuf++ = sin(d + p->contrast * sin(d * 4)) * SOX_SAMPLE_MAX;
}
return SOX_SUCCESS;
}
sox_effect_handler_t const * lsx_contrast_effect_fn(void)
{
static sox_effect_handler_t handler = {"contrast", "[enhancement (75)]",
SOX_EFF_MCHAN, create, NULL, flow, NULL, NULL, NULL, sizeof(priv_t)};
return &handler;
}