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62 lines
1.8 KiB
C
62 lines
1.8 KiB
C
/* libSoX effect: swap pairs of audio channels
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*
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* First version written 01/2012 by Ulrich Klauer.
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* Replaces an older swap effect originally written by Chris Bagwell
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* on March 16, 1999.
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*
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* Copyright 2012 Chris Bagwell and SoX Contributors
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*
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* This library is free software; you can redistribute it and/or modify it
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* under the terms of the GNU Lesser General Public License as published by
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* the Free Software Foundation; either version 2.1 of the License, or (at
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* your option) any later version.
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*
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* This library is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
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* General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this library; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "sox_i.h"
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static int start(sox_effect_t *effp)
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{
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return effp->in_signal.channels >= 2 ? SOX_SUCCESS : SOX_EFF_NULL;
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}
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static int flow(sox_effect_t *effp, const sox_sample_t *ibuf,
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sox_sample_t *obuf, size_t *isamp, size_t *osamp)
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{
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size_t len = min(*isamp, *osamp);
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size_t channels = effp->in_signal.channels;
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len /= channels;
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*isamp = *osamp = len * channels;
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while (len--) {
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size_t i;
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for (i = 0; i + 1 < channels; i += 2) {
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*obuf++ = ibuf[1];
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*obuf++ = ibuf[0];
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ibuf += 2;
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}
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if (channels % 2)
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*obuf++ = *ibuf++;
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}
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return SOX_SUCCESS;
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}
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sox_effect_handler_t const *lsx_swap_effect_fn(void)
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{
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static sox_effect_handler_t handler = {
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"swap", NULL,
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SOX_EFF_MCHAN | SOX_EFF_MODIFY,
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NULL, start, flow, NULL, NULL, NULL,
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0
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};
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return &handler;
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}
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