mpd/src/pcm_channels.c

/*
 * Copyright (C) 2003-2009 The Music Player Daemon Project
 * 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.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#include "pcm_channels.h"
#include "pcm_buffer.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(struct pcm_buffer *buffer,
			uint8_t dest_channels,
			uint8_t src_channels, const int16_t *src,
			size_t src_size, size_t *dest_size_r)
{
	unsigned num_frames = src_size / src_channels / sizeof(*src);
	unsigned dest_size = num_frames * dest_channels * sizeof(*src);
	int16_t *dest = pcm_buffer_get(buffer, dest_size);

	*dest_size_r = dest_size;

	if (src_channels == 1 && dest_channels == 2)
		pcm_convert_channels_16_1_to_2(dest, src, num_frames);
	else if (src_channels == 2 && dest_channels == 1)
		pcm_convert_channels_16_2_to_1(dest, src, num_frames);
	else if (dest_channels == 2)
		pcm_convert_channels_16_n_to_2(dest, src_channels, src,
					       num_frames);
	else
		return NULL;

	return dest;
}

static void
pcm_convert_channels_24_1_to_2(int32_t *dest, const int32_t *src,
			       unsigned num_frames)
{
	while (num_frames-- > 0) {
		int32_t value = *src++;

		*dest++ = value;
		*dest++ = value;
	}
}

static void
pcm_convert_channels_24_2_to_1(int32_t *dest, const int32_t *src,
			       unsigned num_frames)
{
	while (num_frames-- > 0) {
		int32_t a = *src++, b = *src++;

		*dest++ = (a + b) / 2;
	}
}

static void
pcm_convert_channels_24_n_to_2(int32_t *dest,
			       unsigned src_channels, const int32_t *src,
			       unsigned num_frames)
{
	unsigned c;

	assert(src_channels > 0);

	while (num_frames-- > 0) {
		int32_t sum = 0;
		int32_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 int32_t *
pcm_convert_channels_24(struct pcm_buffer *buffer,
			uint8_t dest_channels,
			uint8_t src_channels, const int32_t *src,
			size_t src_size, size_t *dest_size_r)
{
	unsigned num_frames = src_size / src_channels / sizeof(*src);
	unsigned dest_size = num_frames * dest_channels * sizeof(*src);
	int32_t *dest = pcm_buffer_get(buffer, dest_size);

	*dest_size_r = dest_size;

	if (src_channels == 1 && dest_channels == 2)
		pcm_convert_channels_24_1_to_2(dest, src, num_frames);
	else if (src_channels == 2 && dest_channels == 1)
		pcm_convert_channels_24_2_to_1(dest, src, num_frames);
	else if (dest_channels == 2)
		pcm_convert_channels_24_n_to_2(dest, src_channels, src,
					       num_frames);
	else
		return NULL;

	return dest;
}

static void
pcm_convert_channels_32_1_to_2(int32_t *dest, const int32_t *src,
			       unsigned num_frames)
{
	pcm_convert_channels_24_1_to_2(dest, src, num_frames);
}

static void
pcm_convert_channels_32_2_to_1(int32_t *dest, const int32_t *src,
			       unsigned num_frames)
{
	while (num_frames-- > 0) {
		int64_t a = *src++, b = *src++;

		*dest++ = (a + b) / 2;
	}
}

static void
pcm_convert_channels_32_n_to_2(int32_t *dest,
			       unsigned src_channels, const int32_t *src,
			       unsigned num_frames)
{
	unsigned c;

	assert(src_channels > 0);

	while (num_frames-- > 0) {
		int64_t sum = 0;
		int32_t value;

		for (c = 0; c < src_channels; ++c)
			sum += *src++;
		value = sum / (int64_t)src_channels;

		/* XXX this is actually only mono ... */
		*dest++ = value;
		*dest++ = value;
	}
}

const int32_t *
pcm_convert_channels_32(struct pcm_buffer *buffer,
			uint8_t dest_channels,
			uint8_t src_channels, const int32_t *src,
			size_t src_size, size_t *dest_size_r)
{
	unsigned num_frames = src_size / src_channels / sizeof(*src);
	unsigned dest_size = num_frames * dest_channels * sizeof(*src);
	int32_t *dest = pcm_buffer_get(buffer, dest_size);

	*dest_size_r = dest_size;

	if (src_channels == 1 && dest_channels == 2)
		pcm_convert_channels_32_1_to_2(dest, src, num_frames);
	else if (src_channels == 2 && dest_channels == 1)
		pcm_convert_channels_32_2_to_1(dest, src, num_frames);
	else if (dest_channels == 2)
		pcm_convert_channels_32_n_to_2(dest, src_channels, src,
					       num_frames);
	else
		return NULL;

	return dest;
}