1 /*
2 * Copyright (c) 2007 Ian Caulfield
3 *
4 * This file is part of FFmpeg.
5 *
6 * FFmpeg is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
10 *
11 * FFmpeg is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
15 *
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with FFmpeg; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19 */
20
21 #include <stdint.h>
22
23 #include "libavutil/channel_layout.h"
24 #include "get_bits.h"
25 #include "mlp_parse.h"
26 #include "mlp.h"
27
28 static const uint8_t mlp_quants[16] = {
29 16, 20, 24, 0, 0, 0, 0, 0,
30 0, 0, 0, 0, 0, 0, 0, 0,
31 };
32
33 static const uint8_t mlp_channels[32] = {
34 1, 2, 3, 4, 3, 4, 5, 3, 4, 5, 4, 5, 6, 4, 5, 4,
35 5, 6, 5, 5, 6, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
36 };
37
38 static const uint64_t mlp_layout[32] = {
39 AV_CH_LAYOUT_MONO,
40 AV_CH_LAYOUT_STEREO,
41 AV_CH_LAYOUT_2_1,
42 AV_CH_LAYOUT_QUAD,
43 AV_CH_LAYOUT_STEREO|AV_CH_LOW_FREQUENCY,
44 AV_CH_LAYOUT_2_1|AV_CH_LOW_FREQUENCY,
45 AV_CH_LAYOUT_QUAD|AV_CH_LOW_FREQUENCY,
46 AV_CH_LAYOUT_SURROUND,
47 AV_CH_LAYOUT_4POINT0,
48 AV_CH_LAYOUT_5POINT0_BACK,
49 AV_CH_LAYOUT_SURROUND|AV_CH_LOW_FREQUENCY,
50 AV_CH_LAYOUT_4POINT0|AV_CH_LOW_FREQUENCY,
51 AV_CH_LAYOUT_5POINT1_BACK,
52 AV_CH_LAYOUT_4POINT0,
53 AV_CH_LAYOUT_5POINT0_BACK,
54 AV_CH_LAYOUT_SURROUND|AV_CH_LOW_FREQUENCY,
55 AV_CH_LAYOUT_4POINT0|AV_CH_LOW_FREQUENCY,
56 AV_CH_LAYOUT_5POINT1_BACK,
57 AV_CH_LAYOUT_QUAD|AV_CH_LOW_FREQUENCY,
58 AV_CH_LAYOUT_5POINT0_BACK,
59 AV_CH_LAYOUT_5POINT1_BACK,
60 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
61 };
62
mlp_get_major_sync_size(const uint8_t * buf,int bufsize)63 static int mlp_get_major_sync_size(const uint8_t * buf, int bufsize)
64 {
65 int has_extension, extensions = 0;
66 int size = 28;
67 if (bufsize < 28)
68 return -1;
69
70 if (AV_RB32(buf) == 0xf8726fba) {
71 has_extension = buf[25] & 1;
72 if (has_extension) {
73 extensions = buf[26] >> 4;
74 size += 2 + extensions * 2;
75 }
76 }
77 return size;
78 }
79
80 /** Read a major sync info header - contains high level information about
81 * the stream - sample rate, channel arrangement etc. Most of this
82 * information is not actually necessary for decoding, only for playback.
83 * gb must be a freshly initialized GetBitContext with no bits read.
84 */
85
ff_mlp_read_major_sync(void * log,MLPHeaderInfo * mh,GetBitContext * gb)86 int ff_mlp_read_major_sync(void *log, MLPHeaderInfo *mh, GetBitContext *gb)
87 {
88 int ratebits, channel_arrangement, header_size;
89 uint16_t checksum;
90
91 av_assert1(get_bits_count(gb) == 0);
92
93 header_size = mlp_get_major_sync_size(gb->buffer, gb->size_in_bits >> 3);
94 if (header_size < 0 || gb->size_in_bits < header_size << 3) {
95 av_log(log, AV_LOG_ERROR, "packet too short, unable to read major sync\n");
96 return -1;
97 }
98
99 checksum = ff_mlp_checksum16(gb->buffer, header_size - 2);
100 if (checksum != AV_RL16(gb->buffer+header_size-2)) {
101 av_log(log, AV_LOG_ERROR, "major sync info header checksum error\n");
102 return AVERROR_INVALIDDATA;
103 }
104
105 if (get_bits(gb, 24) != 0xf8726f) /* Sync words */
106 return AVERROR_INVALIDDATA;
107
108 mh->stream_type = get_bits(gb, 8);
109 mh->header_size = header_size;
110
111 if (mh->stream_type == 0xbb) {
112 mh->group1_bits = mlp_quants[get_bits(gb, 4)];
113 mh->group2_bits = mlp_quants[get_bits(gb, 4)];
114
115 ratebits = get_bits(gb, 4);
116 mh->group1_samplerate = mlp_samplerate(ratebits);
117 mh->group2_samplerate = mlp_samplerate(get_bits(gb, 4));
118
119 skip_bits(gb, 11);
120
121 mh->channel_arrangement=
122 channel_arrangement = get_bits(gb, 5);
123 mh->channels_mlp = mlp_channels[channel_arrangement];
124 mh->channel_layout_mlp = mlp_layout[channel_arrangement];
125 } else if (mh->stream_type == 0xba) {
126 mh->group1_bits = 24; // TODO: Is this information actually conveyed anywhere?
127 mh->group2_bits = 0;
128
129 ratebits = get_bits(gb, 4);
130 mh->group1_samplerate = mlp_samplerate(ratebits);
131 mh->group2_samplerate = 0;
132
133 skip_bits(gb, 4);
134
135 mh->channel_modifier_thd_stream0 = get_bits(gb, 2);
136 mh->channel_modifier_thd_stream1 = get_bits(gb, 2);
137
138 mh->channel_arrangement=
139 channel_arrangement = get_bits(gb, 5);
140 mh->channels_thd_stream1 = truehd_channels(channel_arrangement);
141 mh->channel_layout_thd_stream1 = truehd_layout(channel_arrangement);
142
143 mh->channel_modifier_thd_stream2 = get_bits(gb, 2);
144
145 channel_arrangement = get_bits(gb, 13);
146 mh->channels_thd_stream2 = truehd_channels(channel_arrangement);
147 mh->channel_layout_thd_stream2 = truehd_layout(channel_arrangement);
148 } else
149 return AVERROR_INVALIDDATA;
150
151 mh->access_unit_size = 40 << (ratebits & 7);
152 mh->access_unit_size_pow2 = 64 << (ratebits & 7);
153
154 skip_bits_long(gb, 48);
155
156 mh->is_vbr = get_bits1(gb);
157
158 mh->peak_bitrate = (get_bits(gb, 15) * mh->group1_samplerate + 8) >> 4;
159
160 mh->num_substreams = get_bits(gb, 4);
161
162 skip_bits_long(gb, 4 + (header_size - 17) * 8);
163
164 return 0;
165 }
166