ref: 80123617fccf01cc375afeff9177027e3d510567
dir: /src/skeleff.c/
/* libSoX effect: Skeleton effect used as sample for creating new effects. * * Copyright 1999-2008 Chris Bagwell And SoX Contributors * * 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" /* Private data for effect */ typedef struct { int localdata; } priv_t; /* * Process command-line options but don't do other * initialization now: effp->in_signal & effp->out_signal are not * yet filled in. */ static int getopts(sox_effect_t * effp, int argc, char UNUSED **argv) { priv_t * UNUSED p = (priv_t *)effp->priv; if (argc != 2) return lsx_usage(effp); p->localdata = atoi(argv[1]); return p->localdata > 0 ? SOX_SUCCESS : SOX_EOF; } /* * Prepare processing. * Do all initializations. */ static int start(sox_effect_t * effp) { if (effp->out_signal.channels == 1) { lsx_fail("Can't run on mono data."); return SOX_EOF; } return SOX_SUCCESS; } /* * Process up to *isamp samples from ibuf and produce up to *osamp samples * in obuf. Write back the actual numbers of samples to *isamp and *osamp. * Return SOX_SUCCESS or, if error occurs, SOX_EOF. */ static int flow(sox_effect_t * effp, const sox_sample_t *ibuf, sox_sample_t *obuf, size_t *isamp, size_t *osamp) { priv_t * UNUSED p = (priv_t *)effp->priv; size_t len, done; switch (effp->out_signal.channels) { case 2: /* Length to process will be buffer length / 2 since we * work with two samples at a time. */ len = min(*isamp, *osamp) / 2; for (done = 0; done < len; done++) { obuf[0] = ibuf[0]; obuf[1] = ibuf[1]; /* Advance buffer by 2 samples */ ibuf += 2; obuf += 2; } *isamp = len * 2; *osamp = len * 2; break; } return SOX_SUCCESS; } /* * Drain out remaining samples if the effect generates any. */ static int drain(sox_effect_t UNUSED * effp, sox_sample_t UNUSED *obuf, size_t *osamp) { *osamp = 0; /* Return SOX_EOF when drain * will not output any more samples. * *osamp == 0 also indicates that. */ return SOX_EOF; } /* * Do anything required when you stop reading samples. */ static int stop(sox_effect_t UNUSED * effp) { return SOX_SUCCESS; } /* * Do anything required when you kill an effect. * (free allocated memory, etc.) */ static int lsx_kill(sox_effect_t UNUSED * effp) { return SOX_SUCCESS; } /* * Function returning effect descriptor. This should be the only * externally visible object. */ const sox_effect_handler_t *lsx_skel_effect_fn(void); const sox_effect_handler_t *lsx_skel_effect_fn(void) { /* * Effect descriptor. * If no specific processing is needed for any of * the 6 functions, then the function above can be deleted * and NULL used in place of the its name below. */ static sox_effect_handler_t sox_skel_effect = { "skel", "[OPTION]", SOX_EFF_MCHAN, getopts, start, flow, drain, stop, lsx_kill, sizeof(priv_t) }; return &sox_skel_effect; }