jcs.org
Serenity Operating System
1/*
2 * Copyright (c) 2020, William McPherson <willmcpherson2@gmail.com>
3 *
4 * SPDX-License-Identifier: BSD-2-Clause
5 */
6
7#include <LibAudio/WavWriter.h>
8#include <LibCore/DeprecatedFile.h>
9
10namespace Audio {
11
12WavWriter::WavWriter(StringView path, int sample_rate, u16 num_channels, u16 bits_per_sample)
13 : m_sample_rate(sample_rate)
14 , m_num_channels(num_channels)
15 , m_bits_per_sample(bits_per_sample)
16{
17 set_file(path);
18}
19
20WavWriter::WavWriter(int sample_rate, u16 num_channels, u16 bits_per_sample)
21 : m_sample_rate(sample_rate)
22 , m_num_channels(num_channels)
23 , m_bits_per_sample(bits_per_sample)
24{
25}
26
27WavWriter::~WavWriter()
28{
29 if (!m_finalized)
30 finalize();
31}
32
33void WavWriter::set_file(StringView path)
34{
35 m_file = Core::DeprecatedFile::construct(path);
36 if (!m_file->open(Core::OpenMode::ReadWrite)) {
37 m_error_string = DeprecatedString::formatted("Can't open file: {}", m_file->error_string());
38 return;
39 }
40 m_file->seek(44);
41 m_finalized = false;
42}
43
44void WavWriter::write_samples(Span<Sample> samples)
45{
46 m_data_sz += samples.size() * sizeof(Sample);
47
48 for (auto const& sample : samples) {
49 // FIXME: This only really works for 16-bit samples.
50 u16 left = static_cast<i16>(sample.left * static_cast<float>(1 << m_bits_per_sample));
51 u16 right = static_cast<i16>(sample.right * static_cast<float>(1 << m_bits_per_sample));
52 // FIXME: This ignores endianness.
53 m_file->write(bit_cast<u8 const*>(&left), sizeof(u16));
54 m_file->write(bit_cast<u8 const*>(&right), sizeof(u16));
55 }
56}
57
58void WavWriter::finalize()
59{
60 VERIFY(!m_finalized);
61 m_finalized = true;
62 if (m_file) {
63 m_file->seek(0);
64 write_header();
65 m_file->close();
66 }
67 m_data_sz = 0;
68}
69
70void WavWriter::write_header()
71{
72 // "RIFF"
73 static u32 riff = 0x46464952;
74 m_file->write(reinterpret_cast<u8*>(&riff), sizeof(riff));
75
76 // Size of data + (size of header - previous field - this field)
77 u32 sz = m_data_sz + (44 - 4 - 4);
78 m_file->write(reinterpret_cast<u8*>(&sz), sizeof(sz));
79
80 // "WAVE"
81 static u32 wave = 0x45564157;
82 m_file->write(reinterpret_cast<u8*>(&wave), sizeof(wave));
83
84 // "fmt "
85 static u32 fmt_id = 0x20746D66;
86 m_file->write(reinterpret_cast<u8*>(&fmt_id), sizeof(fmt_id));
87
88 // Size of the next 6 fields
89 static u32 fmt_size = 16;
90 m_file->write(reinterpret_cast<u8*>(&fmt_size), sizeof(fmt_size));
91
92 // 1 for PCM
93 static u16 audio_format = 1;
94 m_file->write(reinterpret_cast<u8*>(&audio_format), sizeof(audio_format));
95
96 m_file->write(reinterpret_cast<u8*>(&m_num_channels), sizeof(m_num_channels));
97
98 m_file->write(reinterpret_cast<u8*>(&m_sample_rate), sizeof(m_sample_rate));
99
100 u32 byte_rate = m_sample_rate * m_num_channels * (m_bits_per_sample / 8);
101 m_file->write(reinterpret_cast<u8*>(&byte_rate), sizeof(byte_rate));
102
103 u16 block_align = m_num_channels * (m_bits_per_sample / 8);
104 m_file->write(reinterpret_cast<u8*>(&block_align), sizeof(block_align));
105
106 m_file->write(reinterpret_cast<u8*>(&m_bits_per_sample), sizeof(m_bits_per_sample));
107
108 // "data"
109 static u32 chunk_id = 0x61746164;
110 m_file->write(reinterpret_cast<u8*>(&chunk_id), sizeof(chunk_id));
111
112 m_file->write(reinterpret_cast<u8*>(&m_data_sz), sizeof(m_data_sz));
113}
114
115}