3 * MPEG Audio header dissection
4 * Written by Shaun Jackman <sjackman@gmail.com>
5 * Copyright 2007 Shaun Jackman
10 * This program is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU General Public License
12 * as published by the Free Software Foundation; either version 2
13 * of the License, or (at your option) any later version.
15 * This program is distributed in the hope that it will be useful,
16 * but WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 * GNU General Public License for more details.
20 * You should have received a copy of the GNU General Public License
21 * along with this program; if not, write to the Free Software
22 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
25 #include "mpeg-audio.h"
27 static const int mpa_versions
[4] = { 2, -1, 1, 0 };
28 static const int mpa_layers
[4] = { -1, 2, 1, 0 };
30 static const unsigned int mpa_samples_data
[3][3] = {
36 static const unsigned int mpa_bitrates
[3][3][16] = { /* kb/s */
38 { 0, 32, 64, 96, 128, 160, 192, 224, 256, 288, 320, 352, 384, 416, 448 },
39 { 0, 32, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224, 256, 320, 384 },
40 { 0, 32, 40, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224, 256, 320 },
43 { 0, 32, 48, 56, 64, 80, 96, 112, 128, 144, 160, 176, 192, 224, 256 },
44 { 0, 8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 144, 160 },
45 { 0, 8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 144, 160 },
48 { 0, 32, 48, 56, 64, 80, 96, 112, 128, 144, 160, 176, 192, 224, 256 },
49 { 0, 8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 144, 160 },
50 { 0, 8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 144, 160 },
54 static const unsigned int mpa_frequencies
[3][4] = {
55 { 44100, 48000, 32000 },
56 { 22050, 24000, 16000 },
57 { 11025, 12000, 8000 },
60 static const unsigned int mpa_padding_data
[3] = { 4, 1, 1 };
63 mpa_version(const struct mpa
*mpa
)
65 return mpa_versions
[mpa
->version
];
69 mpa_layer(const struct mpa
*mpa
)
71 return mpa_layers
[mpa
->layer
];
75 mpa_samples(const struct mpa
*mpa
)
77 return mpa_samples_data
[mpa_versions
[mpa
->version
]][mpa_layer(mpa
)];
81 mpa_bitrate(const struct mpa
*mpa
)
83 return (1000 * (mpa_bitrates
[mpa_versions
[mpa
->version
]][mpa_layers
[mpa
->layer
]][mpa
->bitrate
]));
87 mpa_frequency(const struct mpa
*mpa
)
89 return(mpa_frequencies
[mpa_versions
[mpa
->version
]][mpa
->frequency
]);
93 mpa_padding(const struct mpa
*mpa
)
95 return(mpa
->padding
? mpa_padding_data
[mpa_layers
[mpa
->layer
]] : 0);