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, void *logctx)
34{
35    if (get_bits_left(gb) < 112)
36        return AVERROR_INVALIDDATA;
37
38    if (get_bits_long(gb, 32) != MKBETAG('A','L','S','\0'))
39        return AVERROR_INVALIDDATA;
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    if (c->sample_rate <= 0) {
46        av_log(logctx, AV_LOG_ERROR, "Invalid sample rate %d\n", c->sample_rate);
47        return AVERROR_INVALIDDATA;
48    }
49
50    // skip number of samples
51    skip_bits_long(gb, 32);
52
53    // read number of channels
54    c->chan_config = 0;
55    c->channels    = get_bits(gb, 16) + 1;
56
57    return 0;
58}
59
60const uint8_t ff_mpeg4audio_channels[14] = {
61    0,
62    1, // mono (1/0)
63    2, // stereo (2/0)
64    3, // 3/0
65    4, // 3/1
66    5, // 3/2
67    6, // 3/2.1
68    8, // 5/2.1
69    0,
70    0,
71    0,
72    7, // 3/3.1
73    8, // 3/2/2.1
74    24 // 3/3/3 - 5/2/3 - 3/0/0.2
75};
76
77static inline int get_object_type(GetBitContext *gb)
78{
79    int object_type = get_bits(gb, 5);
80    if (object_type == AOT_ESCAPE)
81        object_type = 32 + get_bits(gb, 6);
82    return object_type;
83}
84
85static inline int get_sample_rate(GetBitContext *gb, int *index)
86{
87    *index = get_bits(gb, 4);
88    return *index == 0x0f ? get_bits(gb, 24) :
89        ff_mpeg4audio_sample_rates[*index];
90}
91
92int ff_mpeg4audio_get_config_gb(MPEG4AudioConfig *c, GetBitContext *gb,
93                                int sync_extension, void *logctx)
94{
95    int specific_config_bitindex, ret;
96    int start_bit_index = get_bits_count(gb);
97    c->object_type = get_object_type(gb);
98    c->sample_rate = get_sample_rate(gb, &c->sampling_index);
99    c->chan_config = get_bits(gb, 4);
100    if (c->chan_config < FF_ARRAY_ELEMS(ff_mpeg4audio_channels))
101        c->channels = ff_mpeg4audio_channels[c->chan_config];
102    else {
103        av_log(logctx, AV_LOG_ERROR, "Invalid chan_config %d\n", c->chan_config);
104        return AVERROR_INVALIDDATA;
105    }
106    c->sbr = -1;
107    c->ps  = -1;
108    if (c->object_type == AOT_SBR || (c->object_type == AOT_PS &&
109        // check for W6132 Annex YYYY draft MP3onMP4
110        !(show_bits(gb, 3) & 0x03 && !(show_bits(gb, 9) & 0x3F)))) {
111        if (c->object_type == AOT_PS)
112            c->ps = 1;
113        c->ext_object_type = AOT_SBR;
114        c->sbr = 1;
115        c->ext_sample_rate = get_sample_rate(gb, &c->ext_sampling_index);
116        c->object_type = get_object_type(gb);
117        if (c->object_type == AOT_ER_BSAC)
118            c->ext_chan_config = get_bits(gb, 4);
119    } else {
120        c->ext_object_type = AOT_NULL;
121        c->ext_sample_rate = 0;
122    }
123    specific_config_bitindex = get_bits_count(gb);
124
125    if (c->object_type == AOT_ALS) {
126        skip_bits(gb, 5);
127        if (show_bits(gb, 24) != MKBETAG('\0','A','L','S'))
128            skip_bits(gb, 24);
129
130        specific_config_bitindex = get_bits_count(gb);
131
132        ret = parse_config_ALS(gb, c, logctx);
133        if (ret < 0)
134            return ret;
135    }
136
137    if (c->ext_object_type != AOT_SBR && sync_extension) {
138        while (get_bits_left(gb) > 15) {
139            if (show_bits(gb, 11) == 0x2b7) { // sync extension
140                get_bits(gb, 11);
141                c->ext_object_type = get_object_type(gb);
142                if (c->ext_object_type == AOT_SBR && (c->sbr = get_bits1(gb)) == 1) {
143                    c->ext_sample_rate = get_sample_rate(gb, &c->ext_sampling_index);
144                    if (c->ext_sample_rate == c->sample_rate)
145                        c->sbr = -1;
146                }
147                if (get_bits_left(gb) > 11 && get_bits(gb, 11) == 0x548)
148                    c->ps = get_bits1(gb);
149                break;
150            } else
151                get_bits1(gb); // skip 1 bit
152        }
153    }
154
155    //PS requires SBR
156    if (!c->sbr)
157        c->ps = 0;
158    //Limit implicit PS to the HE-AACv2 Profile
159    if ((c->ps == -1 && c->object_type != AOT_AAC_LC) || c->channels & ~0x01)
160        c->ps = 0;
161
162    return specific_config_bitindex - start_bit_index;
163}
164
165int avpriv_mpeg4audio_get_config2(MPEG4AudioConfig *c, const uint8_t *buf,
166                                  int size, int sync_extension, void *logctx)
167{
168    GetBitContext gb;
169    int ret;
170
171    if (size <= 0)
172        return AVERROR_INVALIDDATA;
173
174    ret = init_get_bits8(&gb, buf, size);
175    if (ret < 0)
176        return ret;
177
178    return ff_mpeg4audio_get_config_gb(c, &gb, sync_extension, logctx);
179}
180