FFmpeg
amr.h
Go to the documentation of this 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
31 typedef uint16_t R_TABLE_TYPE;
32 #else
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  */
51 static 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 */
ptrdiff_t const GLvoid * data
Definition: opengl_enc.c:100
uint8_t
ptrdiff_t size
Definition: opengl_enc.c:100
static void ff_amr_bit_reorder(uint16_t *out, int size, const uint8_t *data, const R_TABLE_TYPE *ord_table)
Fill the frame structure variables from bitstream by parsing the given reordering table that uses the...
Definition: amr.h:51
it s the only field you need to keep assuming you have a context There is some magic you don t need to care about around this field
Libavcodec external API header.
uint8_t R_TABLE_TYPE
Definition: amr.h:33
#define bit(string, value)
Definition: cbs_mpeg2.c:58
FILE * out
Definition: movenc.c:54