3 * MPEG Audio header dissection
4 * Written by Shaun Jackman <sjackman@gmail.com>
5 * Copyright 2007 Shaun Jackman
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License
10 * as published by the Free Software Foundation; either version 2
11 * of the License, or (at your option) any later version.
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
26 #include "ws_symbol_export.h"
29 unsigned int emphasis :2;
30 unsigned int original :1;
31 unsigned int copyright :1;
32 unsigned int modeext :2;
35 unsigned int padding :1;
36 unsigned int frequency :2;
37 unsigned int bitrate :4;
38 unsigned int protection :1;
39 unsigned int layer :2;
40 unsigned int version :2;
41 unsigned int sync :11;
44 #define MPA_UNMARSHAL_SYNC(n) ((n) >> 21 & 0x7ff)
45 #define MPA_UNMARSHAL_VERSION(n) ((n) >> 19 & 0x3)
46 #define MPA_UNMARSHAL_LAYER(n) ((n) >> 17 & 0x3)
47 #define MPA_UNMARSHAL_PROTECTION(n) ((n) >> 16 & 0x1)
48 #define MPA_UNMARSHAL_BITRATE(n) ((n) >> 12 & 0xf)
49 #define MPA_UNMARSHAL_FREQUENCY(n) ((n) >> 10 & 0x3)
50 #define MPA_UNMARSHAL_PADDING(n) ((n) >> 9 & 0x1)
51 #define MPA_UNMARSHAL_PRIVATE(n) ((n) >> 8 & 0x1)
52 #define MPA_UNMARSHAL_MODE(n) ((n) >> 6 & 0x3)
53 #define MPA_UNMARSHAL_MODEEXT(n) ((n) >> 4 & 0x3)
54 #define MPA_UNMARSHAL_COPYRIGHT(n) ((n) >> 3 & 0x1)
55 #define MPA_UNMARSHAL_ORIGINAL(n) ((n) >> 2 & 0x1)
56 #define MPA_UNMARSHAL_EMPHASIS(n) ((n) >> 0 & 0x3)
58 #define MPA_UNMARSHAL(mpa, n) do { \
59 (mpa)->sync = MPA_UNMARSHAL_SYNC(n); \
60 (mpa)->version = MPA_UNMARSHAL_VERSION(n); \
61 (mpa)->layer = MPA_UNMARSHAL_LAYER(n); \
62 (mpa)->protection = MPA_UNMARSHAL_PROTECTION(n); \
63 (mpa)->bitrate = MPA_UNMARSHAL_BITRATE(n); \
64 (mpa)->frequency = MPA_UNMARSHAL_FREQUENCY(n); \
65 (mpa)->padding = MPA_UNMARSHAL_PADDING(n); \
66 (mpa)->priv = MPA_UNMARSHAL_PRIVATE(n); \
67 (mpa)->mode = MPA_UNMARSHAL_MODE(n); \
68 (mpa)->modeext = MPA_UNMARSHAL_MODEEXT(n); \
69 (mpa)->copyright = MPA_UNMARSHAL_COPYRIGHT(n); \
70 (mpa)->original = MPA_UNMARSHAL_ORIGINAL(n); \
71 (mpa)->emphasis = MPA_UNMARSHAL_EMPHASIS(n); \
75 int mpa_version(const struct mpa *);
77 int mpa_layer(const struct mpa *);
79 unsigned int mpa_samples(const struct mpa *);
81 unsigned int mpa_bitrate(const struct mpa *);
83 unsigned int mpa_frequency(const struct mpa *);
85 unsigned int mpa_padding(const struct mpa *);
87 #define MPA_DATA_BYTES(mpa) (mpa_bitrate(mpa) * mpa_samples(mpa) \
88 / mpa_frequency(mpa) / 8)
89 #define MPA_BYTES(mpa) (MPA_DATA_BYTES(mpa) + mpa_padding(mpa))
90 #define MPA_DURATION_NS(mpa) \
91 (1000000000 / mpa_frequency(mpa) * mpa_samples(mpa))
93 enum { MPA_SYNC = 0x7ff };
95 #define MPA_SYNC_VALID(mpa) ((mpa)->sync == MPA_SYNC)
96 #define MPA_VERSION_VALID(mpa) (mpa_version(mpa) >= 0)
97 #define MPA_LAYER_VALID(mpa) (mpa_layer(mpa) >= 0)
98 #define MPA_BITRATE_VALID(mpa) (mpa_bitrate(mpa) > 0)
99 #define MPA_FREQUENCY_VALID(mpa) (mpa_frequency(mpa) > 0)
100 #define MPA_VALID(mpa) (MPA_SYNC_VALID(mpa) \
101 && MPA_VERSION_VALID(mpa) && MPA_LAYER_VALID(mpa) \
102 && MPA_BITRATE_VALID(mpa) && MPA_FREQUENCY_VALID(mpa))