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 #include <stdint.h>
20 #include "wave.h"
21
22
23 /**
24 * Id formatting
25 */
26
27 #define __WAVE_ID(s) \
28 (uint32_t)( s[0] | (s[1] << 8) | (s[2] << 16) | (s[3] << 24) )
29
30
31 /**
32 * File format statement
33 * | type_id WAVE_FILE_TYPE_ID
34 * | size File size - 8 bytes
35 * | type_id WAVE_FILE_FMT_ID
36 */
37
38 #define WAVE_FILE_TYPE_ID __WAVE_ID("RIFF")
39 #define WAVE_FILE_FMT_ID __WAVE_ID("WAVE")
40
41 struct wave_file {
42 uint32_t type_id;
43 uint32_t size;
44 uint32_t fmt_id;
45 };
46
47
48 /**
49 * Audio format statement
50 * | id WAVE_FORMAT_ID
51 * | size Size of the block - 8 bytes (= 16 bytes)
52 * | format WAVE_FORMAT_PCM
53 * | channels Number of channels
54 * | samplerate Sampling rate
55 * | byterate Bytes per secondes = `samplerate * framesize`
56 * | framesize Bytes per sampling time = `channels * bitdepth / 8`
57 * | bitdepth Number of bits per sample
58 */
59
60 #define WAVE_FORMAT_ID __WAVE_ID("fmt ")
61 #define WAVE_FORMAT_PCM 1
62
63 struct wave_format {
64 uint32_t id;
65 uint32_t size;
66 uint16_t fmt;
67 uint16_t channels;
68 uint32_t samplerate;
69 uint32_t byterate;
70 uint16_t framesize;
71 uint16_t bitdepth;
72 };
73
74
75 /**
76 * Audio data statement
77 * | id WAV_DATA_ID
78 * | size Size of the data following
79 */
80
81 #define WAVE_DATA_ID __WAVE_ID("data")
82
83 struct wave_data {
84 uint32_t id;
85 uint32_t size;
86 };
87
88
89 /**
90 * Read WAVE file header
91 */
wave_read_header(FILE * fp,int * bitdepth,int * samplesize,int * samplerate,int * nchannels,int * nframes)92 int wave_read_header(FILE *fp, int *bitdepth, int *samplesize,
93 int *samplerate, int *nchannels, int *nframes)
94 {
95 struct wave_file file;
96 struct wave_format format;
97 struct wave_data data;
98
99 if (fread(&file, sizeof(file), 1, fp) != 1
100 || file.type_id != WAVE_FILE_TYPE_ID
101 || file.fmt_id != WAVE_FILE_FMT_ID)
102 return -1;
103
104 if (fread(&format, sizeof(format), 1, fp) != 1
105 || format.id != WAVE_FORMAT_ID
106 || format.fmt != WAVE_FORMAT_PCM
107 || format.byterate != format.samplerate * format.framesize)
108 return -1;
109
110 fseek(fp, sizeof(format) - (8 + format.size), SEEK_CUR);
111
112 if (fread(&data, sizeof(data), 1, fp) != 1
113 || data.id != WAVE_DATA_ID)
114 return -1;
115
116 *bitdepth = format.bitdepth;
117 *samplesize = format.framesize / format.channels;
118 *samplerate = format.samplerate;
119 *nchannels = format.channels;
120 *nframes = data.size / format.framesize;
121
122 return 0;
123 }
124
125 /**
126 * Read PCM samples from wave file
127 */
wave_read_pcm(FILE * fp,int samplesize,int nch,int count,void * buffer)128 int wave_read_pcm(FILE *fp, int samplesize,
129 int nch, int count, void *buffer)
130 {
131 return fread(buffer, nch * samplesize, count, fp);
132 }
133
134 /**
135 * Write WAVE file header
136 */
wave_write_header(FILE * fp,int bitdepth,int samplesize,int samplerate,int nchannels,int nframes)137 void wave_write_header(FILE *fp, int bitdepth, int samplesize,
138 int samplerate, int nchannels, int nframes)
139 {
140 struct {
141 struct wave_file file;
142 struct wave_format format;
143 struct wave_data data;
144 } header;
145
146 long data_size = nchannels * nframes * samplesize;
147 long file_size = sizeof(header) + data_size;
148
149 header.file = (struct wave_file){
150 WAVE_FILE_TYPE_ID, file_size - 8,
151 .fmt_id = WAVE_FILE_FMT_ID
152 };
153
154 header.format = (struct wave_format){
155 WAVE_FORMAT_ID, sizeof(header.format) - 8,
156 .fmt = WAVE_FORMAT_PCM,
157 .channels = nchannels,
158 .samplerate = samplerate,
159 .byterate = samplerate * nchannels * samplesize,
160 .framesize = nchannels * samplesize,
161 .bitdepth = bitdepth,
162 };
163
164 header.data = (struct wave_data){
165 WAVE_DATA_ID, data_size
166 };
167
168 fwrite(&header, sizeof(header), 1, fp);
169 }
170
171 /**
172 * Write PCM samples to wave file
173 */
wave_write_pcm(FILE * fp,int samplesize,const void * _pcm,int nch,int off,int count)174 void wave_write_pcm(FILE *fp, int samplesize,
175 const void *_pcm, int nch, int off, int count)
176 {
177 const int8_t *pcm = _pcm;
178 fwrite(pcm + nch * off * samplesize, nch * samplesize, count, fp);
179 }
180
