pcm_resample.h

/*
 * 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.
 */

#ifndef MPD_PCM_RESAMPLE_H
#define MPD_PCM_RESAMPLE_H

#include "pcm_buffer.h"
#include "config.h"

#include <stdint.h>
#include <stddef.h>
#include <stdbool.h>

#ifdef HAVE_LIBSAMPLERATE
#include <samplerate.h>
#endif

/**
 * This object is statically allocated (within another struct), and
 * holds buffer allocations and the state for the resampler.
 */
struct pcm_resample_state {
#ifdef HAVE_LIBSAMPLERATE
	SRC_STATE *state;
	SRC_DATA data;

	struct pcm_buffer in, out;

	struct {
		unsigned src_rate;
		unsigned dest_rate;
		uint8_t channels;
	} prev;

	bool error;
#endif

	struct pcm_buffer buffer;
};

/**
 * Initializes a pcm_resample_state object.
 */
void pcm_resample_init(struct pcm_resample_state *state);

/**
 * Deinitializes a pcm_resample_state object and frees allocated
 * memory.
 */
void pcm_resample_deinit(struct pcm_resample_state *state);

/**
 * Resamples 16 bit PCM data.
 *
 * @param state an initialized pcm_resample_state object
 * @param channels the number of channels
 * @param src_rate the source sample rate
 * @param src the source PCM buffer
 * @param src_size the size of #src in bytes
 * @param dest_rate the requested destination sample rate
 * @param dest_size_r returns the number of bytes of the destination buffer
 * @return the destination buffer
 */
const int16_t *
pcm_resample_16(struct pcm_resample_state *state,
		uint8_t channels,
		unsigned src_rate,
		const int16_t *src_buffer, size_t src_size,
		unsigned dest_rate,
		size_t *dest_size_r);

/**
 * Resamples 32 bit PCM data.
 *
 * @param state an initialized pcm_resample_state object
 * @param channels the number of channels
 * @param src_rate the source sample rate
 * @param src the source PCM buffer
 * @param src_size the size of #src in bytes
 * @param dest_rate the requested destination sample rate
 * @param dest_size_r returns the number of bytes of the destination buffer
 * @return the destination buffer
 */
const int32_t *
pcm_resample_32(struct pcm_resample_state *state,
		uint8_t channels,
		unsigned src_rate,
		const int32_t *src_buffer, size_t src_size,
		unsigned dest_rate,
		size_t *dest_size_r);

/**
 * Resamples 24 bit PCM data.
 *
 * @param state an initialized pcm_resample_state object
 * @param channels the number of channels
 * @param src_rate the source sample rate
 * @param src the source PCM buffer
 * @param src_size the size of #src in bytes
 * @param dest_rate the requested destination sample rate
 * @param dest_size_r returns the number of bytes of the destination buffer
 * @return the destination buffer
 */
static inline const int32_t *
pcm_resample_24(struct pcm_resample_state *state,
		uint8_t channels,
		unsigned src_rate,
		const int32_t *src_buffer, size_t src_size,
		unsigned dest_rate,
		size_t *dest_size_r)
{
	/* reuse the 32 bit code - the resampler code doesn't care if
	   the upper 8 bits are actually used */
	return pcm_resample_32(state, channels,
			       src_rate, src_buffer, src_size,
			       dest_rate, dest_size_r);
}

#endif