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 <inttypes.h> 41 42 #include "btstack.h" 43 #include "btstack_sample_rate_compensation.h" 44 45 void btstack_sample_rate_compensation_reset(btstack_sample_rate_compensation_t *self, uint32_t timestamp_ms) { 46 self->count = 0; 47 self->last = timestamp_ms; 48 } 49 50 void btstack_sample_rate_compensation_init(btstack_sample_rate_compensation_t *self, uint32_t timestamp_ms, uint32_t sample_rate, uint32_t ratio_Q15) { 51 btstack_sample_rate_compensation_reset( self, timestamp_ms ); 52 self->ratio_state = ratio_Q15 << 1; // Q15 to Q16 is one left shift 53 self->rate_state = sample_rate << 8; 54 #ifdef DEBUG_RATIO_CALCULATION 55 self->ratio = Q15_TO_FLOAT(ratioQ15); 56 self->sample_rate = sample_rate; 57 #endif 58 } 59 60 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) { 61 int32_t delta = timestamp_ms - self->last; 62 if( delta >= 1000 ) { 63 log_debug("current playback sample rate: %" PRId32 "", playback_sample_rate ); 64 65 #ifdef DEBUG_RATIO_CALCULATION 66 { 67 double current_sample_rate = self->count*(1000./delta); 68 double current_ratio = self->sample_rate/playback_sample_rate; 69 70 // exponential weighted moving average 71 const double rate_decay = 0.025; 72 self->sample_rate += rate_decay * (current_sample_rate-self->sample_rate); 73 74 // exponential weighted moving average 75 static const double ratio_decay = 1.3; 76 self->ratio += ratio_decay * (current_ratio-self->ratio); 77 78 log_debug("current l2cap sample rate: %f (%d %d)", current_sample_rate, delta, self->count ); 79 log_debug("current ratio: %f", current_ratio); 80 log_debug("calculated ratio: %f", self->ratio ); 81 } 82 #endif 83 uint32_t fixed_rate = (self->count*(UINT16_C(1)<<15))/delta*1000; // sample rate as Q15 84 uint32_t fixed_ratio = (self->rate_state<<7)/playback_sample_rate; // Q15 85 log_debug("fp current l2cap sample rate: %f (%" PRId32 " %" PRId32 ")", Q15_TO_FLOAT(fixed_rate), delta, self->count); 86 87 self->last = timestamp_ms; 88 self->count = 0; 89 90 // fixed point exponential weighted moving average 91 const int16_t rate_decay = FLOAT_TO_Q15(0.025f); 92 uint32_t rate = self->rate_state >> 8; // integer part only 93 self->rate_state += (rate_decay * (int32_t)((fixed_rate>>15)-rate)) >> (15-8); // Q8; 94 95 // fixed point exponential weighted moving average 96 const int16_t ratio_decay = FLOAT_TO_Q8(1.3f); 97 self->ratio_state += (ratio_decay * (int32_t)((fixed_ratio<<1)-self->ratio_state)) >> (16-8); // Q16 98 99 log_debug("fp current ratio : %f", Q15_TO_FLOAT(fixed_ratio)); 100 log_debug("fp calculated ratio: %f", Q16_TO_FLOAT(self->ratio_state)); 101 log_debug("scale factor Q16: %" PRId32 "", self->ratio_state); 102 } 103 104 self->count += samples; 105 return self->ratio_state; 106 } 107