1 /* 2 * Copyright (C) 2023 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 #define BTSTACK_FILE__ "btstack_sample_rate_comnpensation.h" 39 40 #include "btstack.h" 41 #include "btstack_sample_rate_compensation.h" 42 43 void btstack_sample_rate_compensation_reset(btstack_sample_rate_compensation_t *self, uint32_t timestamp_ms) { 44 self->count = 0; 45 self->last = timestamp_ms; 46 } 47 48 void btstack_sample_rate_compensation_init(btstack_sample_rate_compensation_t *self, uint32_t timestamp_ms, uint32_t sample_rate, uint32_t ratio_Q15) { 49 btstack_sample_rate_compensation_reset( self, timestamp_ms ); 50 self->ratio_state = ratio_Q15 << 1; // Q15 to Q16 is one left shift 51 self->rate_state = sample_rate << 8; 52 #ifdef DEBUG_RATIO_CALCULATION 53 self->ratio = Q15_TO_FLOAT(ratioQ15); 54 self->sample_rate = sample_rate; 55 #endif 56 } 57 58 uint32_t btstack_sample_rate_compensation_update(btstack_sample_rate_compensation_t *self, uint32_t timestamp_ms, uint32_t samples, uint32_t playback_sample_rate) { 59 int32_t delta = timestamp_ms - self->last; 60 if( delta >= 1000 ) { 61 log_debug("current playback sample rate: %d", playback_sample_rate ); 62 63 #ifdef DEBUG_RATIO_CALCULATION 64 { 65 double current_sample_rate = self->count*(1000./delta); 66 double current_ratio = self->sample_rate/playback_sample_rate; 67 68 // exponential weighted moving average 69 const double rate_decay = 0.025; 70 self->sample_rate += rate_decay * (current_sample_rate-self->sample_rate); 71 72 // exponential weighted moving average 73 static const double ratio_decay = 1.3; 74 self->ratio += ratio_decay * (current_ratio-self->ratio); 75 76 log_debug("current l2cap sample rate: %f (%d %d)", current_sample_rate, delta, self->count ); 77 log_debug("current ratio: %f", current_ratio); 78 log_debug("calculated ratio: %f", self->ratio ); 79 } 80 #endif 81 uint32_t fixed_rate = (self->count*(UINT16_C(1)<<15))/delta*1000; // sample rate as Q15 82 uint32_t fixed_ratio = (self->rate_state<<7)/playback_sample_rate; // Q15 83 log_debug("fp current l2cap sample rate: %f (%d %d)", Q15_TO_FLOAT(fixed_rate), delta, self->count); 84 85 self->last = timestamp_ms; 86 self->count = 0; 87 88 // fixed point exponential weighted moving average 89 const int16_t rate_decay = FLOAT_TO_Q15(0.025f); 90 uint32_t rate = self->rate_state >> 8; // integer part only 91 self->rate_state += (rate_decay * (int32_t)((fixed_rate>>15)-rate)) >> (15-8); // Q8; 92 93 // fixed point exponential weighted moving average 94 const int16_t ratio_decay = FLOAT_TO_Q8(1.3f); 95 self->ratio_state += (ratio_decay * (int32_t)((fixed_ratio<<1)-self->ratio_state)) >> (16-8); // Q16 96 97 log_debug("fp current ratio : %f", Q15_TO_FLOAT(fixed_ratio)); 98 log_debug("fp calculated ratio: %f", Q16_TO_FLOAT(self->ratio_state)); 99 log_debug("scale factor Q16: %d", self->ratio_state); 100 } 101 102 self->count += samples; 103 return self->ratio_state; 104 } 105