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 */
33static 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
55const int avpriv_mpeg4audio_sample_rates[16] = {
56    96000, 88200, 64000, 48000, 44100, 32000,
57    24000, 22050, 16000, 12000, 11025, 8000, 7350
58};
59
60const uint8_t ff_mpeg4audio_channels[8] = {
61    0, 1, 2, 3, 4, 5, 6, 8
62};
63
64static 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
72static 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        avpriv_mpeg4audio_sample_rates[*index];
77}
78
79int avpriv_mpeg4audio_get_config(MPEG4AudioConfig *c, const uint8_t *buf,
80                                 int bit_size, int sync_extension)
81{
82    GetBitContext gb;
83    int specific_config_bitindex;
84
85    init_get_bits(&gb, buf, bit_size);
86    c->object_type = get_object_type(&gb);
87    c->sample_rate = get_sample_rate(&gb, &c->sampling_index);
88    c->chan_config = get_bits(&gb, 4);
89    if (c->chan_config < FF_ARRAY_ELEMS(ff_mpeg4audio_channels))
90        c->channels = ff_mpeg4audio_channels[c->chan_config];
91    c->sbr = -1;
92    c->ps  = -1;
93    if (c->object_type == AOT_SBR || (c->object_type == AOT_PS &&
94        // check for W6132 Annex YYYY draft MP3onMP4
95        !(show_bits(&gb, 3) & 0x03 && !(show_bits(&gb, 9) & 0x3F)))) {
96        if (c->object_type == AOT_PS)
97            c->ps = 1;
98        c->ext_object_type = AOT_SBR;
99        c->sbr = 1;
100        c->ext_sample_rate = get_sample_rate(&gb, &c->ext_sampling_index);
101        c->object_type = get_object_type(&gb);
102        if (c->object_type == AOT_ER_BSAC)
103            c->ext_chan_config = get_bits(&gb, 4);
104    } else {
105        c->ext_object_type = AOT_NULL;
106        c->ext_sample_rate = 0;
107    }
108    specific_config_bitindex = get_bits_count(&gb);
109
110    if (c->object_type == AOT_ALS) {
111        skip_bits(&gb, 5);
112        if (show_bits_long(&gb, 24) != MKBETAG('\0','A','L','S'))
113            skip_bits_long(&gb, 24);
114
115        specific_config_bitindex = get_bits_count(&gb);
116
117        if (parse_config_ALS(&gb, c))
118            return -1;
119    }
120
121    if (c->ext_object_type != AOT_SBR && sync_extension) {
122        while (get_bits_left(&gb) > 15) {
123            if (show_bits(&gb, 11) == 0x2b7) { // sync extension
124                get_bits(&gb, 11);
125                c->ext_object_type = get_object_type(&gb);
126                if (c->ext_object_type == AOT_SBR && (c->sbr = get_bits1(&gb)) == 1)
127                    c->ext_sample_rate = get_sample_rate(&gb, &c->ext_sampling_index);
128                if (get_bits_left(&gb) > 11 && get_bits(&gb, 11) == 0x548)
129                    c->ps = get_bits1(&gb);
130                break;
131            } else
132                get_bits1(&gb); // skip 1 bit
133        }
134    }
135
136    //PS requires SBR
137    if (!c->sbr)
138        c->ps = 0;
139    //Limit implicit PS to the HE-AACv2 Profile
140    if ((c->ps == -1 && c->object_type != AOT_AAC_LC) || c->channels & ~0x01)
141        c->ps = 0;
142
143    return specific_config_bitindex;
144}
145
146static av_always_inline unsigned int copy_bits(PutBitContext *pb,
147                                               GetBitContext *gb,
148                                               int bits)
149{
150    unsigned int el = get_bits(gb, bits);
151    put_bits(pb, bits, el);
152    return el;
153}
154
155int avpriv_copy_pce_data(PutBitContext *pb, GetBitContext *gb)
156{
157    int five_bit_ch, four_bit_ch, comment_size, bits;
158    int offset = put_bits_count(pb);
159
160    copy_bits(pb, gb, 10);                  //Tag, Object Type, Frequency
161    five_bit_ch  = copy_bits(pb, gb, 4);    //Front
162    five_bit_ch += copy_bits(pb, gb, 4);    //Side
163    five_bit_ch += copy_bits(pb, gb, 4);    //Back
164    four_bit_ch  = copy_bits(pb, gb, 2);    //LFE
165    four_bit_ch += copy_bits(pb, gb, 3);    //Data
166    five_bit_ch += copy_bits(pb, gb, 4);    //Coupling
167    if (copy_bits(pb, gb, 1))               //Mono Mixdown
168        copy_bits(pb, gb, 4);
169    if (copy_bits(pb, gb, 1))               //Stereo Mixdown
170        copy_bits(pb, gb, 4);
171    if (copy_bits(pb, gb, 1))               //Matrix Mixdown
172        copy_bits(pb, gb, 3);
173    for (bits = five_bit_ch*5+four_bit_ch*4; bits > 16; bits -= 16)
174        copy_bits(pb, gb, 16);
175    if (bits)
176        copy_bits(pb, gb, bits);
177    avpriv_align_put_bits(pb);
178    align_get_bits(gb);
179    comment_size = copy_bits(pb, gb, 8);
180    for (; comment_size > 0; comment_size--)
181        copy_bits(pb, gb, 8);
182
183    return put_bits_count(pb) - offset;
184}
185