/src/wireshark/wsutil/mpeg-audio.c
Line | Count | Source |
1 | | /* mpeg-audio.c |
2 | | * |
3 | | * MPEG Audio header dissection |
4 | | * Written by Shaun Jackman <sjackman@gmail.com> |
5 | | * Copyright 2007 Shaun Jackman |
6 | | * |
7 | | * Wiretap Library |
8 | | * SPDX-License-Identifier: GPL-2.0-or-later |
9 | | */ |
10 | | |
11 | | #include "mpeg-audio.h" |
12 | | |
13 | | static const int mpa_versions[4] = { 2, -1, 1, 0 }; |
14 | | static const int mpa_layers[4] = { -1, 2, 1, 0 }; |
15 | | |
16 | | static const unsigned int mpa_samples_data[3][3] = { |
17 | | { 384, 1152, 1152 }, |
18 | | { 384, 1152, 576 }, |
19 | | { 384, 1152, 576 }, |
20 | | }; |
21 | | |
22 | | static const unsigned int mpa_bitrates[3][3][16] = { /* kb/s */ |
23 | | { |
24 | | { 0, 32, 64, 96, 128, 160, 192, 224, 256, 288, 320, 352, 384, 416, 448 }, |
25 | | { 0, 32, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224, 256, 320, 384 }, |
26 | | { 0, 32, 40, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224, 256, 320 }, |
27 | | }, |
28 | | { |
29 | | { 0, 32, 48, 56, 64, 80, 96, 112, 128, 144, 160, 176, 192, 224, 256 }, |
30 | | { 0, 8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 144, 160 }, |
31 | | { 0, 8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 144, 160 }, |
32 | | }, |
33 | | { |
34 | | { 0, 32, 48, 56, 64, 80, 96, 112, 128, 144, 160, 176, 192, 224, 256 }, |
35 | | { 0, 8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 144, 160 }, |
36 | | { 0, 8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 144, 160 }, |
37 | | }, |
38 | | }; |
39 | | |
40 | | static const unsigned int mpa_frequencies[3][4] = { |
41 | | { 44100, 48000, 32000 }, |
42 | | { 22050, 24000, 16000 }, |
43 | | { 11025, 12000, 8000 }, |
44 | | }; |
45 | | |
46 | | static const unsigned int mpa_padding_data[3] = { 4, 1, 1 }; |
47 | | |
48 | | int |
49 | | mpa_version(const struct mpa *mpa) |
50 | 0 | { |
51 | 0 | return mpa_versions[mpa->version]; |
52 | 0 | } |
53 | | |
54 | | int |
55 | | mpa_layer(const struct mpa *mpa) |
56 | 0 | { |
57 | 0 | return mpa_layers[mpa->layer]; |
58 | 0 | } |
59 | | |
60 | | unsigned |
61 | | mpa_samples(const struct mpa *mpa) |
62 | 0 | { |
63 | 0 | return mpa_samples_data[mpa_versions[mpa->version]][mpa_layer(mpa)]; |
64 | 0 | } |
65 | | |
66 | | unsigned |
67 | | mpa_bitrate(const struct mpa *mpa) |
68 | 0 | { |
69 | 0 | return (1000 * (mpa_bitrates[mpa_versions[mpa->version]][mpa_layers[mpa->layer]][mpa->bitrate])); |
70 | 0 | } |
71 | | |
72 | | unsigned |
73 | | mpa_frequency(const struct mpa *mpa) |
74 | 0 | { |
75 | 0 | return(mpa_frequencies[mpa_versions[mpa->version]][mpa->frequency]); |
76 | 0 | } |
77 | | |
78 | | unsigned |
79 | | mpa_padding(const struct mpa *mpa) |
80 | 0 | { |
81 | 0 | return(mpa->padding ? mpa_padding_data[mpa_layers[mpa->layer]] : 0); |
82 | 0 | } |
83 | | |
84 | | /* Decode an ID3v2 synchsafe integer. |
85 | | * See https://id3.org/id3v2.4.0-structure section 6.2. |
86 | | */ |
87 | | uint32_t |
88 | | decode_synchsafe_int(uint32_t input) |
89 | 0 | { |
90 | 0 | uint32_t value; |
91 | | |
92 | | /* High-order byte */ |
93 | 0 | value = (input >> 24) & 0x7f; |
94 | | /* Shift the result left to make room for the next 7 bits */ |
95 | 0 | value <<= 7; |
96 | | |
97 | | /* Now OR in the 2nd byte */ |
98 | 0 | value |= (input >> 16) & 0x7f; |
99 | 0 | value <<= 7; |
100 | | |
101 | | /* ... and the 3rd */ |
102 | 0 | value |= (input >> 8) & 0x7f; |
103 | 0 | value <<= 7; |
104 | | |
105 | | /* For the 4th byte don't do the shift */ |
106 | 0 | value |= input & 0x7f; |
107 | |
|
108 | 0 | return value; |
109 | 0 | } |
110 | | |
111 | | /* |
112 | | * Editor modelines - https://www.wireshark.org/tools/modelines.html |
113 | | * |
114 | | * Local variables: |
115 | | * c-basic-offset: 8 |
116 | | * tab-width: 8 |
117 | | * indent-tabs-mode: t |
118 | | * End: |
119 | | * |
120 | | * vi: set shiftwidth=8 tabstop=8 noexpandtab: |
121 | | * :indentSize=8:tabSize=8:noTabs=false: |
122 | | */ |