Statistics
| Branch: | Revision:

ffmpeg / libavcodec / mpeg4audio.c @ 2912e87a

History | View | Annotate | Download (6 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 Libav.
7
 *
8
 * Libav 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
 * Libav 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 Libav; 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
/**
28
 * Parse MPEG-4 audio configuration for ALS object type.
29
 * @param[in] gb       bit reader context
30
 * @param[in] c        MPEG4AudioConfig structure to fill
31
 * @return on success 0 is returned, otherwise a value < 0
32
 */
33
static int parse_config_ALS(GetBitContext *gb, MPEG4AudioConfig *c)
34
{
35
    if (get_bits_left(gb) < 112)
36
        return -1;
37

    
38
    if (get_bits_long(gb, 32) != MKBETAG('A','L','S','\0'))
39
        return -1;
40

    
41
    // override AudioSpecificConfig channel configuration and sample rate
42
    // which are buggy in old ALS conformance files
43
    c->sample_rate = get_bits_long(gb, 32);
44

    
45
    // skip number of samples
46
    skip_bits_long(gb, 32);
47

    
48
    // read number of channels
49
    c->chan_config = 0;
50
    c->channels    = get_bits(gb, 16) + 1;
51

    
52
    return 0;
53
}
54

    
55
const int ff_mpeg4audio_sample_rates[16] = {
56
    96000, 88200, 64000, 48000, 44100, 32000,
57
    24000, 22050, 16000, 12000, 11025, 8000, 7350
58
};
59

    
60
const uint8_t ff_mpeg4audio_channels[8] = {
61
    0, 1, 2, 3, 4, 5, 6, 8
62
};
63

    
64
static inline int get_object_type(GetBitContext *gb)
65
{
66
    int object_type = get_bits(gb, 5);
67
    if (object_type == AOT_ESCAPE)
68
        object_type = 32 + get_bits(gb, 6);
69
    return object_type;
70
}
71

    
72
static inline int get_sample_rate(GetBitContext *gb, int *index)
73
{
74
    *index = get_bits(gb, 4);
75
    return *index == 0x0f ? get_bits(gb, 24) :
76
        ff_mpeg4audio_sample_rates[*index];
77
}
78

    
79
int ff_mpeg4audio_get_config(MPEG4AudioConfig *c, const uint8_t *buf, int buf_size)
80
{
81
    GetBitContext gb;
82
    int specific_config_bitindex;
83

    
84
    init_get_bits(&gb, buf, buf_size*8);
85
    c->object_type = get_object_type(&gb);
86
    c->sample_rate = get_sample_rate(&gb, &c->sampling_index);
87
    c->chan_config = get_bits(&gb, 4);
88
    if (c->chan_config < FF_ARRAY_ELEMS(ff_mpeg4audio_channels))
89
        c->channels = ff_mpeg4audio_channels[c->chan_config];
90
    c->sbr = -1;
91
    c->ps  = -1;
92
    if (c->object_type == AOT_SBR || (c->object_type == AOT_PS &&
93
        // check for W6132 Annex YYYY draft MP3onMP4
94
        !(show_bits(&gb, 3) & 0x03 && !(show_bits(&gb, 9) & 0x3F)))) {
95
        if (c->object_type == AOT_PS)
96
            c->ps = 1;
97
        c->ext_object_type = AOT_SBR;
98
        c->sbr = 1;
99
        c->ext_sample_rate = get_sample_rate(&gb, &c->ext_sampling_index);
100
        c->object_type = get_object_type(&gb);
101
        if (c->object_type == AOT_ER_BSAC)
102
            c->ext_chan_config = get_bits(&gb, 4);
103
    } else {
104
        c->ext_object_type = AOT_NULL;
105
        c->ext_sample_rate = 0;
106
    }
107
    specific_config_bitindex = get_bits_count(&gb);
108

    
109
    if (c->object_type == AOT_ALS) {
110
        skip_bits(&gb, 5);
111
        if (show_bits_long(&gb, 24) != MKBETAG('\0','A','L','S'))
112
            skip_bits_long(&gb, 24);
113

    
114
        specific_config_bitindex = get_bits_count(&gb);
115

    
116
        if (parse_config_ALS(&gb, c))
117
            return -1;
118
    }
119

    
120
    if (c->ext_object_type != AOT_SBR) {
121
        while (get_bits_left(&gb) > 15) {
122
            if (show_bits(&gb, 11) == 0x2b7) { // sync extension
123
                get_bits(&gb, 11);
124
                c->ext_object_type = get_object_type(&gb);
125
                if (c->ext_object_type == AOT_SBR && (c->sbr = get_bits1(&gb)) == 1)
126
                    c->ext_sample_rate = get_sample_rate(&gb, &c->ext_sampling_index);
127
                if (get_bits_left(&gb) > 11 && get_bits(&gb, 11) == 0x548)
128
                    c->ps = get_bits1(&gb);
129
                break;
130
            } else
131
                get_bits1(&gb); // skip 1 bit
132
        }
133
    }
134

    
135
    //PS requires SBR
136
    if (!c->sbr)
137
        c->ps = 0;
138
    //Limit implicit PS to the HE-AACv2 Profile
139
    if ((c->ps == -1 && c->object_type != AOT_AAC_LC) || c->channels & ~0x01)
140
        c->ps = 0;
141

    
142
    return specific_config_bitindex;
143
}
144

    
145
static av_always_inline unsigned int copy_bits(PutBitContext *pb,
146
                                               GetBitContext *gb,
147
                                               int bits)
148
{
149
    unsigned int el = get_bits(gb, bits);
150
    put_bits(pb, bits, el);
151
    return el;
152
}
153

    
154
int ff_copy_pce_data(PutBitContext *pb, GetBitContext *gb)
155
{
156
    int five_bit_ch, four_bit_ch, comment_size, bits;
157
    int offset = put_bits_count(pb);
158

    
159
    copy_bits(pb, gb, 10);                  //Tag, Object Type, Frequency
160
    five_bit_ch  = copy_bits(pb, gb, 4);    //Front
161
    five_bit_ch += copy_bits(pb, gb, 4);    //Side
162
    five_bit_ch += copy_bits(pb, gb, 4);    //Back
163
    four_bit_ch  = copy_bits(pb, gb, 2);    //LFE
164
    four_bit_ch += copy_bits(pb, gb, 3);    //Data
165
    five_bit_ch += copy_bits(pb, gb, 4);    //Coupling
166
    if (copy_bits(pb, gb, 1))               //Mono Mixdown
167
        copy_bits(pb, gb, 4);
168
    if (copy_bits(pb, gb, 1))               //Stereo Mixdown
169
        copy_bits(pb, gb, 4);
170
    if (copy_bits(pb, gb, 1))               //Matrix Mixdown
171
        copy_bits(pb, gb, 3);
172
    for (bits = five_bit_ch*5+four_bit_ch*4; bits > 16; bits -= 16)
173
        copy_bits(pb, gb, 16);
174
    if (bits)
175
        copy_bits(pb, gb, bits);
176
    align_put_bits(pb);
177
    align_get_bits(gb);
178
    comment_size = copy_bits(pb, gb, 8);
179
    for (; comment_size > 0; comment_size--)
180
        copy_bits(pb, gb, 8);
181

    
182
    return put_bits_count(pb) - offset;
183
}