libavformat/mca.c

   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
  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
  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
 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
 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 FFInputFormat ff_mca_demuxer = {
 222     .p.name         = "mca",
 223     .p.long_name    = NULL_IF_CONFIG_SMALL("MCA Audio Format"),
 224     .p.extensions   = "mca",
 225     .priv_data_size = sizeof(MCADemuxContext),
 226     .read_probe     = probe,
 227     .read_header    = read_header,
 228     .read_packet    = read_packet,
 229     .read_seek      = read_seek,
 230 };