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/* the Music Player Daemon (MPD)
* Copyright (C) 2008 Max Kellermann <max@duempel.org>
* This project's homepage is: http://www.musicpd.org
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program 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 General Public License for more details.
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include "pcm_channels.h"
#include "utils.h"
#include "log.h"
#include <assert.h>
static void
pcm_convert_channels_16_1_to_2(int16_t *dest, const int16_t *src,
unsigned num_frames)
{
while (num_frames-- > 0) {
int16_t value = *src++;
*dest++ = value;
*dest++ = value;
}
}
static void
pcm_convert_channels_16_2_to_1(int16_t *dest, const int16_t *src,
unsigned num_frames)
{
while (num_frames-- > 0) {
int32_t a = *src++, b = *src++;
*dest++ = (a + b) / 2;
}
}
static void
pcm_convert_channels_16_n_to_2(int16_t *dest,
unsigned src_channels, const int16_t *src,
unsigned num_frames)
{
unsigned c;
assert(src_channels > 0);
while (num_frames-- > 0) {
int32_t sum = 0;
int16_t value;
for (c = 0; c < src_channels; ++c)
sum += *src++;
value = sum / (int)src_channels;
/* XXX this is actually only mono ... */
*dest++ = value;
*dest++ = value;
}
}
const int16_t *
pcm_convert_channels_16(int8_t dest_channels,
int8_t src_channels, const int16_t *src,
size_t src_size, size_t *dest_size_r)
{
static int16_t *buf;
static size_t len;
unsigned num_frames = src_size / src_channels / sizeof(*src);
unsigned dest_size = num_frames * dest_channels * sizeof(*src);
if (dest_size > len) {
len = dest_size;
buf = xrealloc(buf, len);
}
*dest_size_r = dest_size;
if (src_channels == 1 && dest_channels == 2)
pcm_convert_channels_16_1_to_2(buf, src, num_frames);
else if (src_channels == 2 && dest_channels == 1)
pcm_convert_channels_16_2_to_1(buf, src, num_frames);
else if (dest_channels == 2)
pcm_convert_channels_16_n_to_2(buf, src_channels, src,
num_frames);
else {
ERROR("conversion %u->%u channels is not supported\n",
src_channels, dest_channels);
return NULL;
}
return buf;
}
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