btstack/src/btstack_resample.h
2019-05-11 19:08:52 +02:00

90 lines
2.9 KiB
C

/*
* Copyright (C) 2018 BlueKitchen GmbH
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the copyright holders nor the names of
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
* 4. Any redistribution, use, or modification is done solely for
* personal benefit and not for any commercial purpose or for
* monetary gain.
*
* THIS SOFTWARE IS PROVIDED BY BLUEKITCHEN GMBH AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL MATTHIAS
* RINGWALD OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
* THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* Please inquire about commercial licensing options at
* contact@bluekitchen-gmbh.com
*
*/
#ifndef BTSTACK_RESAMPLE_H
#define BTSTACK_RESAMPLE_H
#include <stdint.h>
#if defined __cplusplus
extern "C" {
#endif
/*
* btstack_resample.h
*
* Linear resampling for 16-bit audio code samples using 16 bit/16 bit fixed point math
*/
#define BTSTACK_RESAMPLE_MAX_CHANNELS 2
typedef struct {
uint32_t src_pos;
uint32_t src_step;
int16_t last_sample[BTSTACK_RESAMPLE_MAX_CHANNELS];
int num_channels;
} btstack_resample_t;
/**
* @brief Init resample context
* @param num_channels
* @returns btstack_audio implementation
*/
void btstack_resample_init(btstack_resample_t * context, int num_channels);
/**
* @brief Set resampling factor
* @param factor as fixed point value, identity is 0x10000
*/
void btstack_resample_set_factor(btstack_resample_t * context, uint32_t factor);
/**
* @brief Process block of input samples
* @note size of output buffer is not checked
* @param input_buffer
* @param num_frames
* @param output_buffer
* @returns number destination frames
*/
uint16_t btstack_resample_block(btstack_resample_t * context, const int16_t * input_buffer, uint32_t num_frames, int16_t * output_buffer);
#if defined __cplusplus
}
#endif
#endif