From a0bcbb37f45d6bed7f84e53da567ee485fc9669d Mon Sep 17 00:00:00 2001 From: Max Kellermann Date: Thu, 23 Oct 2008 20:03:14 +0200 Subject: pcm_utils: moved channel conversion functions to pcm_channels.c Separate code from pcm_utils.c to keep it small and simple. --- src/pcm_channels.c | 102 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 102 insertions(+) create mode 100644 src/pcm_channels.c (limited to 'src/pcm_channels.c') diff --git a/src/pcm_channels.c b/src/pcm_channels.c new file mode 100644 index 000000000..6555a3b74 --- /dev/null +++ b/src/pcm_channels.c @@ -0,0 +1,102 @@ +/* the Music Player Daemon (MPD) + * Copyright (C) 2008 Max Kellermann + * 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 + +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; +} -- cgit v1.2.3