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/**
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
55/* XXX: make sure to update the copies in the different encoders if you change
56 * this table */
57const int avpriv_mpeg4audio_sample_rates[16] = {
58    96000, 88200, 64000, 48000, 44100, 32000,
59    24000, 22050, 16000, 12000, 11025, 8000, 7350
60};
61
62const uint8_t ff_mpeg4audio_channels[8] = {
63    0, 1, 2, 3, 4, 5, 6, 8
64};
65
66static inline int get_object_type(GetBitContext *gb)
67{
68    int object_type = get_bits(gb, 5);
69    if (object_type == AOT_ESCAPE)
70        object_type = 32 + get_bits(gb, 6);
71    return object_type;
72}
73
74static inline int get_sample_rate(GetBitContext *gb, int *index)
75{
76    *index = get_bits(gb, 4);
77    return *index == 0x0f ? get_bits(gb, 24) :
78        avpriv_mpeg4audio_sample_rates[*index];
79}
80
81int avpriv_mpeg4audio_get_config(MPEG4AudioConfig *c, const uint8_t *buf,
82                                 int bit_size, int sync_extension)
83{
84    GetBitContext gb;
85    int specific_config_bitindex;
86
87    if (bit_size <= 0 || init_get_bits(&gb, buf, bit_size) < 0)
88        return AVERROR_INVALIDDATA;
89    c->object_type = get_object_type(&gb);
90    c->sample_rate = get_sample_rate(&gb, &c->sampling_index);
91    c->chan_config = get_bits(&gb, 4);
92    if (c->chan_config < FF_ARRAY_ELEMS(ff_mpeg4audio_channels))
93        c->channels = ff_mpeg4audio_channels[c->chan_config];
94    c->sbr = -1;
95    c->ps  = -1;
96    if (c->object_type == AOT_SBR || (c->object_type == AOT_PS &&
97        // check for W6132 Annex YYYY draft MP3onMP4
98        !(show_bits(&gb, 3) & 0x03 && !(show_bits(&gb, 9) & 0x3F)))) {
99        if (c->object_type == AOT_PS)
100            c->ps = 1;
101        c->ext_object_type = AOT_SBR;
102        c->sbr = 1;
103        c->ext_sample_rate = get_sample_rate(&gb, &c->ext_sampling_index);
104        c->object_type = get_object_type(&gb);
105        if (c->object_type == AOT_ER_BSAC)
106            c->ext_chan_config = get_bits(&gb, 4);
107    } else {
108        c->ext_object_type = AOT_NULL;
109        c->ext_sample_rate = 0;
110    }
111    specific_config_bitindex = get_bits_count(&gb);
112
113    if (c->object_type == AOT_ALS) {
114        skip_bits(&gb, 5);
115        if (show_bits_long(&gb, 24) != MKBETAG('\0','A','L','S'))
116            skip_bits_long(&gb, 24);
117
118        specific_config_bitindex = get_bits_count(&gb);
119
120        if (parse_config_ALS(&gb, c))
121            return -1;
122    }
123
124    if (c->ext_object_type != AOT_SBR && sync_extension) {
125        while (get_bits_left(&gb) > 15) {
126            if (show_bits(&gb, 11) == 0x2b7) { // sync extension
127                get_bits(&gb, 11);
128                c->ext_object_type = get_object_type(&gb);
129                if (c->ext_object_type == AOT_SBR && (c->sbr = get_bits1(&gb)) == 1) {
130                    c->ext_sample_rate = get_sample_rate(&gb, &c->ext_sampling_index);
131                    if (c->ext_sample_rate == c->sample_rate)
132                        c->sbr = -1;
133                }
134                if (get_bits_left(&gb) > 11 && get_bits(&gb, 11) == 0x548)
135                    c->ps = get_bits1(&gb);
136                break;
137            } else
138                get_bits1(&gb); // skip 1 bit
139        }
140    }
141
142    //PS requires SBR
143    if (!c->sbr)
144        c->ps = 0;
145    //Limit implicit PS to the HE-AACv2 Profile
146    if ((c->ps == -1 && c->object_type != AOT_AAC_LC) || c->channels & ~0x01)
147        c->ps = 0;
148
149    return specific_config_bitindex;
150}
151
152static av_always_inline unsigned int copy_bits(PutBitContext *pb,
153                                               GetBitContext *gb,
154                                               int bits)
155{
156    unsigned int el = get_bits(gb, bits);
157    put_bits(pb, bits, el);
158    return el;
159}
160
161int avpriv_copy_pce_data(PutBitContext *pb, GetBitContext *gb)
162{
163    int five_bit_ch, four_bit_ch, comment_size, bits;
164    int offset = put_bits_count(pb);
165
166    copy_bits(pb, gb, 10);                  //Tag, Object Type, Frequency
167    five_bit_ch  = copy_bits(pb, gb, 4);    //Front
168    five_bit_ch += copy_bits(pb, gb, 4);    //Side
169    five_bit_ch += copy_bits(pb, gb, 4);    //Back
170    four_bit_ch  = copy_bits(pb, gb, 2);    //LFE
171    four_bit_ch += copy_bits(pb, gb, 3);    //Data
172    five_bit_ch += copy_bits(pb, gb, 4);    //Coupling
173    if (copy_bits(pb, gb, 1))               //Mono Mixdown
174        copy_bits(pb, gb, 4);
175    if (copy_bits(pb, gb, 1))               //Stereo Mixdown
176        copy_bits(pb, gb, 4);
177    if (copy_bits(pb, gb, 1))               //Matrix Mixdown
178        copy_bits(pb, gb, 3);
179    for (bits = five_bit_ch*5+four_bit_ch*4; bits > 16; bits -= 16)
180        copy_bits(pb, gb, 16);
181    if (bits)
182        copy_bits(pb, gb, bits);
183    avpriv_align_put_bits(pb);
184    align_get_bits(gb);
185    comment_size = copy_bits(pb, gb, 8);
186    for (; comment_size > 0; comment_size--)
187        copy_bits(pb, gb, 8);
188
189    return put_bits_count(pb) - offset;
190}
191