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
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
|
#include <LibCore/CFile.h>
#include <AK/BufferStream.h>
#include <limits>
#include "AWavLoader.h"
#include "ABuffer.h"
RefPtr<ABuffer> AWavLoader::load_wav(const StringView& path)
{
m_error_string = {};
CFile wav(path);
if (!wav.open(CIODevice::ReadOnly)) {
m_error_string = String::format("Can't open file: %s", wav.error_string());
return nullptr;
}
auto contents = wav.read_all();
return parse_wav(contents);
}
// TODO: A streaming parser might be better than forcing a ByteBuffer
RefPtr<ABuffer> AWavLoader::parse_wav(ByteBuffer& buffer)
{
BufferStream stream(buffer);
#define CHECK_OK(msg) \
do { \
ASSERT(ok); \
if (stream.handle_read_failure()) { \
m_error_string = String::format("Premature stream EOF at %s", msg); \
return {}; \
} \
if (!ok) { \
m_error_string = String::format("Parsing failed: %s", msg); \
return {}; \
} else { \
dbgprintf("%s is OK!\n", msg); \
} \
} while (0);
bool ok = true;
u32 riff; stream >> riff;
ok = ok && riff == 0x46464952; // "RIFF"
CHECK_OK("RIFF header");
u32 sz; stream >> sz;
ok = ok && sz < 1024 * 1024 * 42; // arbitrary
CHECK_OK("File size");
ASSERT(sz < 1024 * 1024 * 42);
u32 wave; stream >> wave;
ok = ok && wave == 0x45564157; // "WAVE"
CHECK_OK("WAVE header");
u32 fmt_id; stream >> fmt_id;
ok = ok && fmt_id == 0x20746D66; // "FMT"
CHECK_OK("FMT header");
u32 fmt_size; stream >> fmt_size;
ok = ok && fmt_size == 16;
CHECK_OK("FMT size");
ASSERT(fmt_size == 16);
u16 audio_format; stream >> audio_format;
CHECK_OK("Audio format"); // incomplete read check
ok = ok && audio_format == 1; // WAVE_FORMAT_PCM
ASSERT(audio_format == 1);
CHECK_OK("Audio format"); // value check
u16 num_channels; stream >> num_channels;
ok = ok && (num_channels == 1 || num_channels == 2);
CHECK_OK("Channel count");
u32 sample_rate; stream >> sample_rate;
CHECK_OK("Sample rate");
u32 byte_rate; stream >> byte_rate;
CHECK_OK("Byte rate");
u16 block_align; stream >> block_align;
CHECK_OK("Block align");
u16 bits_per_sample; stream >> bits_per_sample;
CHECK_OK("Bits per sample"); // incomplete read check
ok = ok && (bits_per_sample == 8 || bits_per_sample == 16);
ASSERT(bits_per_sample == 8 || bits_per_sample == 16);
CHECK_OK("Bits per sample"); // value check
// Read chunks until we find DATA
bool found_data = false;
u32 data_sz = 0;
while (true) {
u32 chunk_id; stream >> chunk_id;
CHECK_OK("Reading chunk ID searching for data");
stream >> data_sz;
CHECK_OK("Reading chunk size searching for data");
if (chunk_id == 0x61746164) { // DATA
found_data = true;
break;
}
}
ok = ok && found_data;
CHECK_OK("Found no data chunk");
ASSERT(found_data);
ok = ok && data_sz < std::numeric_limits<int>::max();
CHECK_OK("Data was too large");
// ### consider using BufferStream to do this for us
ok = ok && int(data_sz) <= (buffer.size() - stream.offset());
CHECK_OK("Bad DATA (truncated)");
// Just make sure we're good before we read the data...
ASSERT(!stream.handle_read_failure());
auto sample_data = buffer.slice(stream.offset(), data_sz);
dbgprintf("Read WAV of format PCM with num_channels %d sample rate %d, bits per sample %d\n", num_channels, sample_rate, bits_per_sample);
return ABuffer::from_pcm_data(sample_data, num_channels, bits_per_sample, sample_rate);
}
// Small helper to resample from one playback rate to another
// This isn't really "smart", in that we just insert (or drop) samples.
// Should do better...
class AResampleHelper {
public:
AResampleHelper(float source, float target);
bool read_sample();
void prepare();
private:
const float m_ratio;
float m_current_ratio { 0 };
};
AResampleHelper::AResampleHelper(float source, float target)
: m_ratio(source / target)
{
}
void AResampleHelper::prepare()
{
m_current_ratio += m_ratio;
}
bool AResampleHelper::read_sample()
{
if (m_current_ratio > 1) {
m_current_ratio--;
return true;
}
return false;
}
template <typename T>
static void read_samples_from_stream(BufferStream& stream, Vector<ASample>& samples, int num_channels, int source_rate)
{
AResampleHelper resampler(source_rate, 44100);
T sample = 0;
float norm_l = 0;
float norm_r = 0;
switch (num_channels) {
case 1:
while (!stream.handle_read_failure()) {
resampler.prepare();
while (resampler.read_sample()) {
stream >> sample;
norm_l = float(sample) / std::numeric_limits<T>::max();
}
samples.append(ASample(norm_l));
}
break;
case 2:
while (!stream.handle_read_failure()) {
resampler.prepare();
while (resampler.read_sample()) {
stream >> sample;
norm_l = float(sample) / std::numeric_limits<T>::max();
stream >> sample;
norm_r = float(sample) / std::numeric_limits<T>::max();
}
samples.append(ASample(norm_l, norm_r));
}
break;
default:
ASSERT_NOT_REACHED();
}
}
// ### can't const this because BufferStream is non-const
// perhaps we need a reading class separate from the writing one, that can be
// entirely consted.
RefPtr<ABuffer> ABuffer::from_pcm_data(ByteBuffer& data, int num_channels, int bits_per_sample, int source_rate)
{
BufferStream stream(data);
Vector<ASample> fdata;
fdata.ensure_capacity(data.size() * 2);
dbg() << "Reading " << bits_per_sample << " bits and " << num_channels << " channels, total bytes: " << data.size();
switch (bits_per_sample) {
case 8:
read_samples_from_stream<u8>(stream, fdata, num_channels, source_rate);
break;
case 16:
read_samples_from_stream<i16>(stream, fdata, num_channels, source_rate);
break;
default:
ASSERT_NOT_REACHED();
}
// We should handle this in a better way above, but for now --
// just make sure we're good. Worst case we just write some 0s where they
// don't belong.
ASSERT(!stream.handle_read_failure());
return adopt(*new ABuffer(fdata));
}
|
