dlib.audio.sample source code

1 /*
2 Copyright (c) 2016-2021 Timur Gafarov
3 
4 Boost Software License - Version 1.0 - August 17th, 2003
5 
6 Permission is hereby granted, free of charge, to any person or organization
7 obtaining a copy of the software and accompanying documentation covered by
8 this license (the "Software") to use, reproduce, display, distribute,
9 execute, and transmit the Software, and to prepare derivative works of the
10 Software, and to permit third-parties to whom the Software is furnished to
11 do so, all subject to the following:
12 
13 The copyright notices in the Software and this entire statement, including
14 the above license grant, this restriction and the following disclaimer,
15 must be included in all copies of the Software, in whole or in part, and
16 all derivative works of the Software, unless such copies or derivative
17 works are solely in the form of machine-executable object code generated by
18 a source language processor.
19 
20 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
21 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
22 FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
23 SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
24 FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
25 ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
26 DEALINGS IN THE SOFTWARE.
27 */
28 
29 /**
30  * Sample types and conversion utilities
31  *
32  * Copyright: Timur Gafarov 2016-2021.
33  * License: $(LINK2 boost.org/LICENSE_1_0.txt, Boost License 1.0).
34  * Authors: Timur Gafarov
35  */
36 module dlib.audio.sample;
37 
38 /**
39  * dlib.audio defines four integer sample formats: signed 8-bit, signed 16-bit,
40  * unsigned 8-bit, unsigned 16-bit.
41  * They are for storage only. All sound processing and sample I/O
42  * should be done in floating point numbers. Floating point sample is signed and
43  * ranges from -1.0f to 1.0f.
44  */
45 enum SampleFormat
46 {
47     /// signed 8-bit
48     S8,
49     /// signed 16-bit
50     S16,
51     /// unsigned 8-bit
52     U8,
53     /// unsigned 16-bit
54     U16
55 }
56 
57 /**
58  * Convert integer sample to floating point sample
59  */
60 float toFloatSample(ubyte* ptr, SampleFormat format)
61 {
62     float res;
63     switch (format)
64     {
65         case SampleFormat.S8:
66             res = *cast(byte*)ptr;
67             res /= byte.max;
68             break;
69         case SampleFormat.S16:
70             res = *cast(short*)ptr;
71             res /= short.max;
72             break;
73         case SampleFormat.U8:
74             res = *ptr;
75             res /= ubyte.max;
76             res = res * 2.0f - 1.0f; // normalize to range -1..1
77             break;
78         case SampleFormat.U16:
79             res = *cast(ushort*)ptr;
80             res /= ushort.max;
81             res = res * 2.0f - 1.0f; // normalize to range -1..1
82             break;
83         default:
84             break;
85     }
86     return res;
87 }
88 
89 /**
90  * Convert floating point sample to integer sample
91  */
92 void fromFloatSample(ubyte* ptr, SampleFormat format, float s)
93 {
94     switch (format)
95     {
96         case SampleFormat.S8:
97             *cast(byte*)ptr = cast(byte)(s * byte.max);
98             break;
99         case SampleFormat.S16:
100             *cast(short*)ptr = cast(short)(s * short.max);
101             break;
102         case SampleFormat.U8:
103             *cast(ubyte*)ptr = cast(ubyte)((s + 1.0f) * 0.5f * ubyte.max);
104             break;
105         case SampleFormat.U16:
106             *cast(ushort*)ptr = cast(ushort)((s + 1.0f) * 0.5f * ushort.max);
107             break;
108         default:
109             break;
110     }
111 }