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 MATTHIAS 24 * RINGWALD 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 #include "btstack_resample.h" 39 40 void btstack_resample_init(btstack_resample_t * context, int num_channels){ 41 context->src_pos = 0; 42 context->src_step = 0x10000; // default resampling 1.0 43 context->last_sample[0] = 0; 44 context->last_sample[1] = 0; 45 context->num_channels = num_channels; 46 } 47 48 void btstack_resample_set_factor(btstack_resample_t * context, uint32_t src_step){ 49 context->src_step = src_step; 50 } 51 52 uint16_t btstack_resample_block(btstack_resample_t * context, const int16_t * input_buffer, uint32_t num_frames, int16_t * output_buffer){ 53 uint16_t dest_frames = 0; 54 uint16_t dest_samples = 0; 55 // samples between last sample of previous block and first sample in current block 56 while (context->src_pos >= 0xffff0000){ 57 const uint16_t t = context->src_pos & 0xffff; 58 int i; 59 for (i=0;i<context->num_channels;i++){ 60 int s1 = context->last_sample[i]; 61 int s2 = input_buffer[i]; 62 int os = (s1*(0x10000 - t) + s2*t) >> 16; 63 output_buffer[dest_samples++] = os; 64 } 65 dest_frames++; 66 context->src_pos += context->src_step; 67 } 68 // process current block 69 while (1){ 70 const uint16_t src_pos = context->src_pos >> 16; 71 const uint16_t t = context->src_pos & 0xffff; 72 int index = src_pos * context->num_channels; 73 int i; 74 if (src_pos >= (num_frames - 1)){ 75 // store last sample 76 for (i=0;i<context->num_channels;i++){ 77 context->last_sample[i] = input_buffer[index++]; 78 } 79 // samples processed 80 context->src_pos -= num_frames << 16; 81 break; 82 } 83 for (i=0;i<context->num_channels;i++){ 84 int s1 = input_buffer[index]; 85 int s2 = input_buffer[index+context->num_channels]; 86 int os = (s1*(0x10000 - t) + s2*t) >> 16; 87 output_buffer[dest_samples++] = os; 88 index++; 89 } 90 dest_frames++; 91 context->src_pos += context->src_step; 92 } 93 return dest_frames; 94 } 95