aboutsummaryrefslogtreecommitdiffstats
path: root/src/wavreader.c
blob: c8bb05d199d4884582b47ce3f593a04f1e7bd66e (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
/* ------------------------------------------------------------------
 * Copyright (C) 2009 Martin Storsjo
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
 * express or implied.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 * -------------------------------------------------------------------
 */

#include "wavreader.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>

#define TAG(a, b, c, d) (((a) << 24) | ((b) << 16) | ((c) << 8) | (d))

struct wav_reader {
    FILE *wav;
    uint32_t data_length;

    int format;
    int sample_rate;
    int bits_per_sample;
    int channels;
    int byte_rate;
    int block_align;

    int streamed;
};

static uint32_t read_tag(struct wav_reader* wr) {
    uint32_t tag = 0;
    tag = (tag << 8) | fgetc(wr->wav);
    tag = (tag << 8) | fgetc(wr->wav);
    tag = (tag << 8) | fgetc(wr->wav);
    tag = (tag << 8) | fgetc(wr->wav);
    return tag;
}

static uint32_t read_int32(struct wav_reader* wr) {
    uint32_t value = 0;
    value |= fgetc(wr->wav) <<  0;
    value |= fgetc(wr->wav) <<  8;
    value |= fgetc(wr->wav) << 16;
    value |= fgetc(wr->wav) << 24;
    return value;
}

static uint16_t read_int16(struct wav_reader* wr) {
    uint16_t value = 0;
    value |= fgetc(wr->wav) << 0;
    value |= fgetc(wr->wav) << 8;
    return value;
}

static void skip(FILE *f, int n) {
    int i;
    for (i = 0; i < n; i++)
        fgetc(f);
}

void* wav_read_open(const char *filename) {
    struct wav_reader* wr = (struct wav_reader*) malloc(sizeof(*wr));
    long data_pos = 0;
    memset(wr, 0, sizeof(*wr));

    if (!strcmp(filename, "-"))
        wr->wav = stdin;
    else
        wr->wav = fopen(filename, "rb");
    if (wr->wav == NULL) {
        free(wr);
        return NULL;
    }

    while (1) {
        uint32_t tag, tag2, length;
        tag = read_tag(wr);
        if (feof(wr->wav))
            break;
        length = read_int32(wr);
        if (!length || length >= 0x7fff0000) {
            wr->streamed = 1;
            length = ~0;
        }
        if (tag != TAG('R', 'I', 'F', 'F') || length < 4) {
            fseek(wr->wav, length, SEEK_CUR);
            continue;
        }
        tag2 = read_tag(wr);
        length -= 4;
        if (tag2 != TAG('W', 'A', 'V', 'E')) {
            fseek(wr->wav, length, SEEK_CUR);
            continue;
        }
        // RIFF chunk found, iterate through it
        while (length >= 8) {
            uint32_t subtag, sublength;
            subtag = read_tag(wr);
            if (feof(wr->wav))
                break;
            sublength = read_int32(wr);
            length -= 8;
            if (length < sublength)
                break;
            if (subtag == TAG('f', 'm', 't', ' ')) {
                if (sublength < 16) {
                    // Insufficient data for 'fmt '
                    break;
                }
                wr->format          = read_int16(wr);
                wr->channels        = read_int16(wr);
                wr->sample_rate     = read_int32(wr);
                wr->byte_rate       = read_int32(wr);
                wr->block_align     = read_int16(wr);
                wr->bits_per_sample = read_int16(wr);
                if (wr->format == 0xfffe) {
                    if (sublength < 28) {
                        // Insufficient data for waveformatex
                        break;
                    }
                    skip(wr->wav, 8);
                    wr->format = read_int32(wr);
                    skip(wr->wav, sublength - 28);
                } else {
                    skip(wr->wav, sublength - 16);
                }
            } else if (subtag == TAG('d', 'a', 't', 'a')) {
                data_pos = ftell(wr->wav);
                wr->data_length = sublength;
                if (!wr->data_length || wr->streamed) {
                    wr->streamed = 1;
                    return wr;
                }
                fseek(wr->wav, sublength, SEEK_CUR);
            } else {
                skip(wr->wav, sublength);
            }
            length -= sublength;
        }
        if (length > 0) {
            // Bad chunk?
            fseek(wr->wav, length, SEEK_CUR);
        }
    }
    fseek(wr->wav, data_pos, SEEK_SET);
    return wr;
}

void wav_read_close(void* obj) {
    struct wav_reader* wr = (struct wav_reader*) obj;
    if (wr->wav != stdin)
        fclose(wr->wav);
    free(wr);
}

int wav_get_header(void* obj, int* format, int* channels, int* sample_rate, int* bits_per_sample, unsigned int* data_length) {
    struct wav_reader* wr = (struct wav_reader*) obj;
    if (format)
        *format = wr->format;
    if (channels)
        *channels = wr->channels;
    if (sample_rate)
        *sample_rate = wr->sample_rate;
    if (bits_per_sample)
        *bits_per_sample = wr->bits_per_sample;
    if (data_length)
        *data_length = wr->data_length;
    return wr->format && wr->sample_rate;
}

int wav_read_data(void* obj, unsigned char* data, unsigned int length) {
    struct wav_reader* wr = (struct wav_reader*) obj;
    int n;
    if (wr->wav == NULL)
        return -1;
    if (length > wr->data_length && !wr->streamed)
        length = wr->data_length;
    n = fread(data, 1, length, wr->wav);
    wr->data_length -= length;
    return n;
}