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/libavcodec/amr.h

http://github.com/FFmpeg/FFmpeg
C Header | 70 lines | 27 code | 7 blank | 36 comment | 2 complexity | dff06ae98d88d9e701d815dcdf795f25 MD5 | raw file
 1/*
 2 * Shared functions between AMR codecs
 3 *
 4 * Copyright (c) 2010 Marcelo Galvao Povoa
 5 *
 6 * This file is part of FFmpeg.
 7 *
 8 * FFmpeg is free software; you can redistribute it and/or
 9 * modify it under the terms of the GNU Lesser General Public
10 * License as published by the Free Software Foundation; either
11 * version 2.1 of the License, or (at your option) any later version.
12 *
13 * FFmpeg 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 GNU
16 * Lesser General Public License for more details.
17 *
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with FFmpeg; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21 */
22
23#ifndef AVCODEC_AMR_H
24#define AVCODEC_AMR_H
25
26#include <string.h>
27
28#include "avcodec.h"
29
30#ifdef AMR_USE_16BIT_TABLES
31typedef uint16_t R_TABLE_TYPE;
32#else
33typedef uint8_t R_TABLE_TYPE;
34#endif
35
36/**
37 * Fill the frame structure variables from bitstream by parsing the
38 * given reordering table that uses the following format:
39 *
40 * Each field (16 bits) in the AMR Frame is stored as:
41 * - one byte for the number of bits in the field
42 * - one byte for the field index
43 * - then, one byte for each bit of the field (from most-significant to least)
44 *         of the position of that bit in the AMR frame.
45 *
46 * @param out pointer to the frame struct
47 * @param size the size in bytes of the frame struct
48 * @param data input bitstream after the frame header
49 * @param ord_table the reordering table as above
50 */
51static inline void ff_amr_bit_reorder(uint16_t *out, int size,
52                                      const uint8_t *data,
53                                      const R_TABLE_TYPE *ord_table)
54{
55    int field_size;
56
57    memset(out, 0, size);
58    while ((field_size = *ord_table++)) {
59        int field = 0;
60        int field_offset = *ord_table++;
61        while (field_size--) {
62           int bit = *ord_table++;
63           field <<= 1;
64           field |= data[bit >> 3] >> (bit & 7) & 1;
65        }
66        out[field_offset >> 1] = field;
67    }
68}
69
70#endif /* AVCODEC_AMR_H */