1 /******************************************************************************
2  *
3  *  Copyright 2022 Google LLC
4  *
5  *  Licensed under the Apache License, Version 2.0 (the "License");
6  *  you may not use this file except in compliance with the License.
7  *  You may obtain a copy of the License at:
8  *
9  *  http://www.apache.org/licenses/LICENSE-2.0
10  *
11  *  Unless required by applicable law or agreed to in writing, software
12  *  distributed under the License is distributed on an "AS IS" BASIS,
13  *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14  *  See the License for the specific language governing permissions and
15  *  limitations under the License.
16  *
17  ******************************************************************************/
18 
19 #ifndef __LC3_LTPF_H
20 #define __LC3_LTPF_H
21 
22 #include "common.h"
23 #include "bits.h"
24 
25 
26 /**
27  * LTPF data
28  */
29 
30 typedef struct lc3_ltpf_data {
31     bool active;
32     int pitch_index;
33 } lc3_ltpf_data_t;
34 
35 
36 /* ----------------------------------------------------------------------------
37  *  Encoding
38  * -------------------------------------------------------------------------- */
39 
40 /**
41  * LTPF analysis
42  * dt, sr          Duration and samplerate of the frame
43  * ltpf            Context of analysis
44  * allowed         True when activation of LTPF is allowed
45  * x               [-d..-1] Previous, [0..ns-1] Current samples
46  * data            Return bitstream data
47  * return          True when pitch present, False otherwise
48  *
49  * The `x` vector is aligned on 32 bits
50  * The number of previous samples `d` accessed on `x` is :
51  *   d: { 10, 20, 30, 40, 60 } - 1 for samplerates from 8KHz to 48KHz
52  */
53 bool lc3_ltpf_analyse(enum lc3_dt dt, enum lc3_srate sr,
54     lc3_ltpf_analysis_t *ltpf, const int16_t *x, lc3_ltpf_data_t *data);
55 
56 /**
57  * LTPF disable
58  * data            LTPF data, disabled activation on return
59  */
60 void lc3_ltpf_disable(lc3_ltpf_data_t *data);
61 
62 /**
63  * Return number of bits coding the bitstream data
64  * pitch           True when pitch present, False otherwise
65  * return          Bit consumption, including the pitch present flag
66  */
67 int lc3_ltpf_get_nbits(bool pitch);
68 
69 /**
70  * Put bitstream data
71  * bits            Bitstream context
72  * data            LTPF data
73  */
74 void lc3_ltpf_put_data(lc3_bits_t *bits, const lc3_ltpf_data_t *data);
75 
76 
77 /* ----------------------------------------------------------------------------
78  *  Decoding
79  * -------------------------------------------------------------------------- */
80 /**
81  * Get bitstream data
82  * bits            Bitstream context
83  * data            Return bitstream data
84  */
85 void lc3_ltpf_get_data(lc3_bits_t *bits, lc3_ltpf_data_t *data);
86 
87 /**
88  * LTPF synthesis
89  * dt, sr          Duration and samplerate of the frame
90  * nbytes          Size in bytes of the frame
91  * ltpf            Context of synthesis
92  * data            Bitstream data, NULL when pitch not present
93  * xr              Base address of ring buffer of decoded samples
94  * x               Samples to proceed in the ring buffer, filtered as output
95  *
96  * The size of the ring buffer is `nh + ns`.
97  * The filtering needs an history of at least 18 ms.
98  */
99 void lc3_ltpf_synthesize(enum lc3_dt dt, enum lc3_srate sr, int nbytes,
100     lc3_ltpf_synthesis_t *ltpf, const lc3_ltpf_data_t *data,
101     const float *xr, float *x);
102 
103 
104 #endif /* __LC3_LTPF_H */
105