1 /* 2 * Copyright (C) 2018 BlueKitchen GmbH 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. Neither the name of the copyright holders nor the names of 14 * contributors may be used to endorse or promote products derived 15 * from this software without specific prior written permission. 16 * 4. Any redistribution, use, or modification is done solely for 17 * personal benefit and not for any commercial purpose or for 18 * monetary gain. 19 * 20 * THIS SOFTWARE IS PROVIDED BY BLUEKITCHEN GMBH AND CONTRIBUTORS 21 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 22 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 23 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL BLUEKITCHEN 24 * GMBH OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 25 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 26 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS 27 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 28 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 29 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF 30 * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 * Please inquire about commercial licensing options at 34 * [email protected] 35 * 36 */ 37 38 /** 39 * @title Lienar Resampling 40 * 41 * Linear resampling for 16-bit audio code samples using 16 bit/16 bit fixed point math. 42 * 43 */ 44 45 #ifndef BTSTACK_RESAMPLE_H 46 #define BTSTACK_RESAMPLE_H 47 48 #include <stdint.h> 49 50 #if defined __cplusplus 51 extern "C" { 52 #endif 53 54 #define BTSTACK_RESAMPLE_MAX_CHANNELS 2 55 56 typedef struct { 57 uint32_t src_pos; 58 uint32_t src_step; 59 int16_t last_sample[BTSTACK_RESAMPLE_MAX_CHANNELS]; 60 int num_channels; 61 } btstack_resample_t; 62 63 /* API_START */ 64 65 /** 66 * @brief Init resample context 67 * @param num_channels 68 * @return btstack_audio implementation 69 */ 70 void btstack_resample_init(btstack_resample_t * context, int num_channels); 71 72 /** 73 * @brief Set resampling factor 74 * @param factor as fixed point value, identity is 0x10000 75 */ 76 void btstack_resample_set_factor(btstack_resample_t * context, uint32_t factor); 77 78 /** 79 * @brief Process block of input samples 80 * @note size of output buffer is not checked 81 * @param input_buffer 82 * @param num_frames 83 * @param output_buffer 84 * @return number destination frames 85 */ 86 uint16_t btstack_resample_block(btstack_resample_t * context, const int16_t * input_buffer, uint32_t num_frames, int16_t * output_buffer); 87 88 /* API_END */ 89 90 #if defined __cplusplus 91 } 92 #endif 93 94 #endif 95