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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
31 unsigned copyright :1;
36 unsigned frequency :2;
38 unsigned protection :1;
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)->private = 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); \
74 int mpa_version(const struct mpa *);
75 int mpa_layer(const struct mpa *);
76 unsigned mpa_samples(const struct mpa *);
77 unsigned mpa_bitrate(const struct mpa *);
78 unsigned mpa_frequency(const struct mpa *);
79 unsigned mpa_padding(const struct mpa *);
81 #define MPA_DATA_BYTES(mpa) (mpa_bitrate(mpa) * mpa_samples(mpa) \
82 / mpa_frequency(mpa) / 8)
83 #define MPA_BYTES(mpa) (MPA_DATA_BYTES(mpa) + mpa_padding(mpa))
84 #define MPA_DURATION_NS(mpa) \
85 (1000000000 / mpa_frequency(mpa) * mpa_samples(mpa))
87 enum { MPA_SYNC = 0x7ff };
89 #define MPA_SYNC_VALID(mpa) ((mpa)->sync == MPA_SYNC)
90 #define MPA_VERSION_VALID(mpa) (mpa_version(mpa) >= 0)
91 #define MPA_LAYER_VALID(mpa) (mpa_layer(mpa) >= 0)
92 #define MPA_BITRATE_VALID(mpa) (mpa_bitrate(mpa) > 0)
93 #define MPA_FREQUENCY_VALID(mpa) (mpa_frequency(mpa) > 0)
94 #define MPA_VALID(mpa) (MPA_SYNC_VALID(mpa) \
95 && MPA_VERSION_VALID(mpa) && MPA_LAYER_VALID(mpa) \
96 && MPA_BITRATE_VALID(mpa) && MPA_FREQUENCY_VALID(mpa))