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,
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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
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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
btstack_sample_rate_compensation_reset(btstack_sample_rate_compensation_t * self,uint32_t timestamp_ms)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
btstack_sample_rate_compensation_init(btstack_sample_rate_compensation_t * self,uint32_t timestamp_ms,uint32_t sample_rate,uint32_t ratio_Q15)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
btstack_sample_rate_compensation_update(btstack_sample_rate_compensation_t * self,uint32_t timestamp_ms,uint32_t samples,uint32_t playback_sample_rate)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