Statistics
| Branch: | Revision:

ffmpeg / libavcodec / mpeg4audio.c @ 0cc4701a

History | View | Annotate | Download (4.37 KB)

1
/*
2
 * MPEG-4 Audio common code
3
 * Copyright (c) 2008 Baptiste Coudurier <baptiste.coudurier@free.fr>
4
 * Copyright (c) 2009 Alex Converse <alex.converse@gmail.com>
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
#include "get_bits.h"
24
#include "put_bits.h"
25
#include "mpeg4audio.h"
26

    
27
const int ff_mpeg4audio_sample_rates[16] = {
28
    96000, 88200, 64000, 48000, 44100, 32000,
29
    24000, 22050, 16000, 12000, 11025, 8000, 7350
30
};
31

    
32
const uint8_t ff_mpeg4audio_channels[8] = {
33
    0, 1, 2, 3, 4, 5, 6, 8
34
};
35

    
36
static inline int get_object_type(GetBitContext *gb)
37
{
38
    int object_type = get_bits(gb, 5);
39
    if (object_type == AOT_ESCAPE)
40
        object_type = 32 + get_bits(gb, 6);
41
    return object_type;
42
}
43

    
44
static inline int get_sample_rate(GetBitContext *gb, int *index)
45
{
46
    *index = get_bits(gb, 4);
47
    return *index == 0x0f ? get_bits(gb, 24) :
48
        ff_mpeg4audio_sample_rates[*index];
49
}
50

    
51
int ff_mpeg4audio_get_config(MPEG4AudioConfig *c, const uint8_t *buf, int buf_size)
52
{
53
    GetBitContext gb;
54
    int specific_config_bitindex;
55

    
56
    init_get_bits(&gb, buf, buf_size*8);
57
    c->object_type = get_object_type(&gb);
58
    c->sample_rate = get_sample_rate(&gb, &c->sampling_index);
59
    c->chan_config = get_bits(&gb, 4);
60
    c->sbr = -1;
61
    if (c->object_type == AOT_SBR) {
62
        c->ext_object_type = c->object_type;
63
        c->sbr = 1;
64
        c->ext_sample_rate = get_sample_rate(&gb, &c->ext_sampling_index);
65
        c->object_type = get_object_type(&gb);
66
        if (c->object_type == AOT_ER_BSAC)
67
            c->ext_chan_config = get_bits(&gb, 4);
68
    } else {
69
        c->ext_object_type = AOT_NULL;
70
        c->ext_sample_rate = 0;
71
    }
72
    specific_config_bitindex = get_bits_count(&gb);
73

    
74
    if (c->ext_object_type != AOT_SBR) {
75
        int bits_left = buf_size*8 - specific_config_bitindex;
76
        for (; bits_left > 15; bits_left--) {
77
            if (show_bits(&gb, 11) == 0x2b7) { // sync extension
78
                get_bits(&gb, 11);
79
                c->ext_object_type = get_object_type(&gb);
80
                if (c->ext_object_type == AOT_SBR && (c->sbr = get_bits1(&gb)) == 1)
81
                    c->ext_sample_rate = get_sample_rate(&gb, &c->ext_sampling_index);
82
                break;
83
            } else
84
                get_bits1(&gb); // skip 1 bit
85
        }
86
    }
87
    return specific_config_bitindex;
88
}
89

    
90
static av_always_inline unsigned int copy_bits(PutBitContext *pb,
91
                                               GetBitContext *gb,
92
                                               int bits)
93
{
94
    unsigned int el = get_bits(gb, bits);
95
    put_bits(pb, bits, el);
96
    return el;
97
}
98

    
99
int ff_copy_pce_data(PutBitContext *pb, GetBitContext *gb)
100
{
101
    int five_bit_ch, four_bit_ch, comment_size, bits;
102
    int offset = put_bits_count(pb);
103

    
104
    copy_bits(pb, gb, 10);                  //Tag, Object Type, Frequency
105
    five_bit_ch  = copy_bits(pb, gb, 4);    //Front
106
    five_bit_ch += copy_bits(pb, gb, 4);    //Side
107
    five_bit_ch += copy_bits(pb, gb, 4);    //Back
108
    four_bit_ch  = copy_bits(pb, gb, 2);    //LFE
109
    four_bit_ch += copy_bits(pb, gb, 3);    //Data
110
    five_bit_ch += copy_bits(pb, gb, 4);    //Coupling
111
    if (copy_bits(pb, gb, 1))               //Mono Mixdown
112
        copy_bits(pb, gb, 4);
113
    if (copy_bits(pb, gb, 1))               //Stereo Mixdown
114
        copy_bits(pb, gb, 4);
115
    if (copy_bits(pb, gb, 1))               //Matrix Mixdown
116
        copy_bits(pb, gb, 3);
117
    for (bits = five_bit_ch*5+four_bit_ch*4; bits > 16; bits -= 16)
118
        copy_bits(pb, gb, 16);
119
    if (bits)
120
        copy_bits(pb, gb, bits);
121
    align_put_bits(pb);
122
    align_get_bits(gb);
123
    comment_size = copy_bits(pb, gb, 8);
124
    for (; comment_size > 0; comment_size--)
125
        copy_bits(pb, gb, 8);
126

    
127
    return put_bits_count(pb) - offset;
128
}