1 /*
2 * MCA demuxer
3 * Copyright (c) 2020 Zixing Liu
4 *
5 * This file is part of FFmpeg.
6 *
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22 #include "libavutil/intreadwrite.h"
23 #include "avformat.h"
24 #include "avio_internal.h"
25 #include "demux.h"
26 #include "internal.h"
27
28 typedef struct MCADemuxContext {
29 uint32_t block_count;
30 uint16_t block_size;
31 uint32_t current_block;
32 uint32_t data_start;
33 uint32_t samples_per_block;
34 } MCADemuxContext;
35
probe(const AVProbeData * p)36 static int probe(const AVProbeData *p)
37 {
38 if (AV_RL32(p->buf) == MKTAG('M', 'A', 'D', 'P') &&
39 AV_RL16(p->buf + 4) <= 0x5)
40 return AVPROBE_SCORE_MAX / 3 * 2;
41 return 0;
42 }
43
read_header(AVFormatContext * s)44 static int read_header(AVFormatContext *s)
45 {
46 AVStream *st;
47 MCADemuxContext *m = s->priv_data;
48 AVCodecParameters *par;
49 int64_t file_size = avio_size(s->pb);
50 uint16_t version = 0;
51 uint32_t header_size, data_size, data_offset, loop_start, loop_end,
52 nb_samples, nb_metadata, coef_offset = 0;
53 int ch, ret;
54 int64_t ret_size;
55
56 st = avformat_new_stream(s, NULL);
57 if (!st)
58 return AVERROR(ENOMEM);
59 par = st->codecpar;
60 par->codec_type = AVMEDIA_TYPE_AUDIO;
61
62 // parse file headers
63 avio_skip(s->pb, 0x4); // skip the file magic
64 version = avio_rl16(s->pb);
65 avio_skip(s->pb, 0x2); // padding
66 par->ch_layout.nb_channels = avio_r8(s->pb);
67 avio_skip(s->pb, 0x1); // padding
68 m->block_size = avio_rl16(s->pb);
69 nb_samples = avio_rl32(s->pb);
70 par->sample_rate = avio_rl32(s->pb);
71 loop_start = avio_rl32(s->pb);
72 loop_end = avio_rl32(s->pb);
73 header_size = avio_rl32(s->pb);
74 data_size = avio_rl32(s->pb);
75 avio_skip(s->pb, 0x4);
76 nb_metadata = avio_rl16(s->pb);
77 avio_skip(s->pb, 0x2); // unknown u16 field
78
79 // samples per frame = 14; frame size = 8 (2^3)
80 m->samples_per_block = (m->block_size * 14) >> 3;
81
82 if (m->samples_per_block < 1)
83 return AVERROR_INVALIDDATA;
84
85 m->block_count = nb_samples / m->samples_per_block;
86 st->duration = nb_samples;
87
88 // sanity checks
89 if (!par->ch_layout.nb_channels || par->sample_rate <= 0
90 || loop_start > loop_end || m->block_count < 1)
91 return AVERROR_INVALIDDATA;
92 if ((ret = av_dict_set_int(&s->metadata, "loop_start",
93 av_rescale(loop_start, AV_TIME_BASE,
94 par->sample_rate), 0)) < 0)
95 return ret;
96 if ((ret = av_dict_set_int(&s->metadata, "loop_end",
97 av_rescale(loop_end, AV_TIME_BASE,
98 par->sample_rate), 0)) < 0)
99 return ret;
100 if ((32 + 4 + m->block_size) > (INT_MAX / par->ch_layout.nb_channels) ||
101 (32 + 4 + m->block_size) * par->ch_layout.nb_channels > INT_MAX - 8)
102 return AVERROR_INVALIDDATA;
103 avpriv_set_pts_info(st, 64, 1, par->sample_rate);
104
105 if (version <= 4) {
106 // version <= 4 needs to use the file size to calculate the offsets
107 if (file_size < 0) {
108 return AVERROR(EIO);
109 }
110 if (file_size - data_size > UINT32_MAX)
111 return AVERROR_INVALIDDATA;
112 m->data_start = file_size - data_size;
113 if (version <= 3) {
114 nb_metadata = 0;
115 // header_size is not available or incorrect in older versions
116 header_size = m->data_start;
117 }
118 } else if (version == 5) {
119 // read data_start location from the header
120 if (0x30 * par->ch_layout.nb_channels + 0x4 > header_size)
121 return AVERROR_INVALIDDATA;
122 data_offset = header_size - 0x30 * par->ch_layout.nb_channels - 0x4;
123 if ((ret_size = avio_seek(s->pb, data_offset, SEEK_SET)) < 0)
124 return ret_size;
125 m->data_start = avio_rl32(s->pb);
126 // check if the metadata is reasonable
127 if (file_size > 0 && (int64_t)m->data_start + data_size > file_size) {
128 // the header is broken beyond repair
129 if ((int64_t)header_size + data_size > file_size) {
130 av_log(s, AV_LOG_ERROR,
131 "MCA metadata corrupted, unable to determine the data offset.\n");
132 return AVERROR_INVALIDDATA;
133 }
134 // recover the data_start information from the data size
135 av_log(s, AV_LOG_WARNING,
136 "Incorrect header size found in metadata, "
137 "header size approximated from the data size\n");
138 if (file_size - data_offset > UINT32_MAX)
139 return AVERROR_INVALIDDATA;
140 m->data_start = file_size - data_size;
141 }
142 } else {
143 avpriv_request_sample(s, "version %d", version);
144 return AVERROR_PATCHWELCOME;
145 }
146
147 // coefficient alignment = 0x30; metadata size = 0x14
148 if (0x30 * par->ch_layout.nb_channels + nb_metadata * 0x14 > header_size)
149 return AVERROR_INVALIDDATA;
150 coef_offset =
151 header_size - 0x30 * par->ch_layout.nb_channels + nb_metadata * 0x14;
152
153 st->start_time = 0;
154 par->codec_id = AV_CODEC_ID_ADPCM_THP_LE;
155
156 ret = ff_alloc_extradata(st->codecpar, 32 * par->ch_layout.nb_channels);
157 if (ret < 0)
158 return ret;
159
160 if ((ret_size = avio_seek(s->pb, coef_offset, SEEK_SET)) < 0)
161 return ret_size;
162 for (ch = 0; ch < par->ch_layout.nb_channels; ch++) {
163 if ((ret = ffio_read_size(s->pb, par->extradata + ch * 32, 32)) < 0)
164 return ret;
165 // 0x30 (alignment) - 0x20 (actual size, 32) = 0x10 (padding)
166 avio_skip(s->pb, 0x10);
167 }
168
169 // seek to the beginning of the adpcm data
170 // there are some files where the adpcm audio data is not immediately after the header
171 if ((ret_size = avio_seek(s->pb, m->data_start, SEEK_SET)) < 0)
172 return ret_size;
173
174 return 0;
175 }
176
read_packet(AVFormatContext * s,AVPacket * pkt)177 static int read_packet(AVFormatContext *s, AVPacket *pkt)
178 {
179 AVCodecParameters *par = s->streams[0]->codecpar;
180 MCADemuxContext *m = s->priv_data;
181 uint16_t size = m->block_size;
182 uint32_t samples = m->samples_per_block;
183 int ret = 0;
184
185 if (avio_feof(s->pb))
186 return AVERROR_EOF;
187 m->current_block++;
188 if (m->current_block > m->block_count)
189 return AVERROR_EOF;
190
191 if ((ret = av_get_packet(s->pb, pkt, size * par->ch_layout.nb_channels)) < 0)
192 return ret;
193 pkt->duration = samples;
194 pkt->stream_index = 0;
195
196 return 0;
197 }
198
read_seek(AVFormatContext * s,int stream_index,int64_t timestamp,int flags)199 static int read_seek(AVFormatContext *s, int stream_index,
200 int64_t timestamp, int flags)
201 {
202 AVStream *st = s->streams[stream_index];
203 MCADemuxContext *m = s->priv_data;
204 int64_t ret = 0;
205
206 if (timestamp < 0)
207 timestamp = 0;
208 timestamp /= m->samples_per_block;
209 if (timestamp >= m->block_count)
210 timestamp = m->block_count - 1;
211 ret = avio_seek(s->pb, m->data_start + timestamp * m->block_size *
212 st->codecpar->ch_layout.nb_channels, SEEK_SET);
213 if (ret < 0)
214 return ret;
215
216 m->current_block = timestamp;
217 avpriv_update_cur_dts(s, st, timestamp * m->samples_per_block);
218 return 0;
219 }
220
221 const AVInputFormat ff_mca_demuxer = {
222 .name = "mca",
223 .long_name = NULL_IF_CONFIG_SMALL("MCA Audio Format"),
224 .priv_data_size = sizeof(MCADemuxContext),
225 .read_probe = probe,
226 .read_header = read_header,
227 .read_packet = read_packet,
228 .read_seek = read_seek,
229 .extensions = "mca",
230 };
231