3 * MPEG Audio header dissection
4 * Written by Shaun Jackman <sjackman@gmail.com>
5 * Copyright 2007 Shaun Jackman
8 * SPDX-License-Identifier: GPL-2.0-or-later
14 #include "ws_symbol_export.h"
17 unsigned int emphasis :2;
18 unsigned int original :1;
19 unsigned int copyright :1;
20 unsigned int modeext :2;
23 unsigned int padding :1;
24 unsigned int frequency :2;
25 unsigned int bitrate :4;
26 unsigned int protection :1;
27 unsigned int layer :2;
28 unsigned int version :2;
29 unsigned int sync :11;
32 #define MPA_UNMARSHAL_SYNC(n) ((n) >> 21 & 0x7ff)
33 #define MPA_UNMARSHAL_VERSION(n) ((n) >> 19 & 0x3)
34 #define MPA_UNMARSHAL_LAYER(n) ((n) >> 17 & 0x3)
35 #define MPA_UNMARSHAL_PROTECTION(n) ((n) >> 16 & 0x1)
36 #define MPA_UNMARSHAL_BITRATE(n) ((n) >> 12 & 0xf)
37 #define MPA_UNMARSHAL_FREQUENCY(n) ((n) >> 10 & 0x3)
38 #define MPA_UNMARSHAL_PADDING(n) ((n) >> 9 & 0x1)
39 #define MPA_UNMARSHAL_PRIVATE(n) ((n) >> 8 & 0x1)
40 #define MPA_UNMARSHAL_MODE(n) ((n) >> 6 & 0x3)
41 #define MPA_UNMARSHAL_MODEEXT(n) ((n) >> 4 & 0x3)
42 #define MPA_UNMARSHAL_COPYRIGHT(n) ((n) >> 3 & 0x1)
43 #define MPA_UNMARSHAL_ORIGINAL(n) ((n) >> 2 & 0x1)
44 #define MPA_UNMARSHAL_EMPHASIS(n) ((n) >> 0 & 0x3)
46 #define MPA_UNMARSHAL(mpa, n) do { \
47 (mpa)->sync = MPA_UNMARSHAL_SYNC(n); \
48 (mpa)->version = MPA_UNMARSHAL_VERSION(n); \
49 (mpa)->layer = MPA_UNMARSHAL_LAYER(n); \
50 (mpa)->protection = MPA_UNMARSHAL_PROTECTION(n); \
51 (mpa)->bitrate = MPA_UNMARSHAL_BITRATE(n); \
52 (mpa)->frequency = MPA_UNMARSHAL_FREQUENCY(n); \
53 (mpa)->padding = MPA_UNMARSHAL_PADDING(n); \
54 (mpa)->priv = MPA_UNMARSHAL_PRIVATE(n); \
55 (mpa)->mode = MPA_UNMARSHAL_MODE(n); \
56 (mpa)->modeext = MPA_UNMARSHAL_MODEEXT(n); \
57 (mpa)->copyright = MPA_UNMARSHAL_COPYRIGHT(n); \
58 (mpa)->original = MPA_UNMARSHAL_ORIGINAL(n); \
59 (mpa)->emphasis = MPA_UNMARSHAL_EMPHASIS(n); \
63 int mpa_version(const struct mpa *);
65 int mpa_layer(const struct mpa *);
67 unsigned int mpa_samples(const struct mpa *);
69 unsigned int mpa_bitrate(const struct mpa *);
71 unsigned int mpa_frequency(const struct mpa *);
73 unsigned int mpa_padding(const struct mpa *);
75 #define MPA_DATA_BYTES(mpa) (mpa_bitrate(mpa) * mpa_samples(mpa) \
76 / mpa_frequency(mpa) / 8)
77 #define MPA_BYTES(mpa) (MPA_DATA_BYTES(mpa) + mpa_padding(mpa))
78 #define MPA_DURATION_NS(mpa) \
79 (1000000000 / mpa_frequency(mpa) * mpa_samples(mpa))
81 enum { MPA_SYNC = 0x7ff };
83 #define MPA_SYNC_VALID(mpa) ((mpa)->sync == MPA_SYNC)
84 #define MPA_VERSION_VALID(mpa) (mpa_version(mpa) >= 0)
85 #define MPA_LAYER_VALID(mpa) (mpa_layer(mpa) >= 0)
86 #define MPA_BITRATE_VALID(mpa) (mpa_bitrate(mpa) > 0)
87 #define MPA_FREQUENCY_VALID(mpa) (mpa_frequency(mpa) > 0)
88 #define MPA_VALID(mpa) (MPA_SYNC_VALID(mpa) \
89 && MPA_VERSION_VALID(mpa) && MPA_LAYER_VALID(mpa) \
90 && MPA_BITRATE_VALID(mpa) && MPA_FREQUENCY_VALID(mpa))