libavformat/mpc8.c

   1 /*
   2  * Musepack SV8 demuxer
   3  * Copyright (c) 2007 Konstantin Shishkov
   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 "libavcodec/get_bits.h"
  23 #include "libavcodec/unary.h"
  24 #include "avformat.h"
  25
  26 /// Two-byte MPC tag
  27 #define MKMPCTAG(a, b) (a | (b << 8))
  28
  29 #define TAG_MPCK MKTAG('M','P','C','K')
  30
  31 /// Reserved MPC tags
  32 enum MPCPacketTags{
  33     TAG_STREAMHDR   = MKMPCTAG('S','H'),
  34     TAG_STREAMEND   = MKMPCTAG('S','E'),
  35
  36     TAG_AUDIOPACKET = MKMPCTAG('A','P'),
  37
  38     TAG_SEEKTBLOFF  = MKMPCTAG('S','O'),
  39     TAG_SEEKTABLE   = MKMPCTAG('S','T'),
  40
  41     TAG_REPLAYGAIN  = MKMPCTAG('R','G'),
  42     TAG_ENCINFO     = MKMPCTAG('E','I'),
  43 };
  44
  45 static const int mpc8_rate[8] = { 44100, 48000, 37800, 32000, -1, -1, -1, -1 };
  46
  47 typedef struct {
  48     int ver;
  49     int frame;
  50     int64_t header_pos;
  51     int64_t samples;
  52 } MPCContext;
  53
  54 static inline int64_t bs_get_v(uint8_t **bs)
  55 {
  56     int64_t v = 0;
  57     int br = 0;
  58     int c;
  59
  60     do {
  61         c = **bs; (*bs)++;
  62         v <<= 7;
  63         v |= c & 0x7F;
  64         br++;
  65         if (br > 10)
  66             return -1;
  67     } while (c & 0x80);
  68
  69     return v - br;
  70 }
  71
  72 static int mpc8_probe(AVProbeData *p)
  73 {
  74     uint8_t *bs = p->buf + 4;
  75     uint8_t *bs_end = bs + p->buf_size;
  76     int64_t size;
  77
  78     if (p->buf_size < 16)
  79         return 0;
  80     if (AV_RL32(p->buf) != TAG_MPCK)
  81         return 0;
  82     while (bs < bs_end + 3) {
  83         int header_found = (bs[0] == 'S' && bs[1] == 'H');
  84         if (bs[0] < 'A' || bs[0] > 'Z' || bs[1] < 'A' || bs[1] > 'Z')
  85             return 0;
  86         bs += 2;
  87         size = bs_get_v(&bs);
  88         if (size < 2)
  89             return 0;
  90         if (bs + size - 2 >= bs_end)
  91             return AVPROBE_SCORE_MAX / 4 - 1; //seems to be valid MPC but no header yet
  92         if (header_found) {
  93             if (size < 11 || size > 28)
  94                 return 0;
  95             if (!AV_RL32(bs)) //zero CRC is invalid
  96                 return 0;
  97             return AVPROBE_SCORE_MAX;
  98         } else {
  99             bs += size - 2;
 100         }
 101     }
 102     return 0;
 103 }
 104
 105 static inline int64_t gb_get_v(GetBitContext *gb)
 106 {
 107     int64_t v = 0;
 108     int bits = 0;
 109     while(get_bits1(gb) && bits < 64-7){
 110         v <<= 7;
 111         v |= get_bits(gb, 7);
 112         bits += 7;
 113     }
 114     v <<= 7;
 115     v |= get_bits(gb, 7);
 116
 117     return v;
 118 }
 119
 120 static void mpc8_get_chunk_header(ByteIOContext *pb, int *tag, int64_t *size)
 121 {
 122     int64_t pos;
 123     pos = url_ftell(pb);
 124     *tag = get_le16(pb);
 125     *size = ff_get_v(pb);
 126     *size -= url_ftell(pb) - pos;
 127 }
 128
 129 static void mpc8_parse_seektable(AVFormatContext *s, int64_t off)
 130 {
 131     MPCContext *c = s->priv_data;
 132     int tag;
 133     int64_t size, pos, ppos[2];
 134     uint8_t *buf;
 135     int i, t, seekd;
 136     GetBitContext gb;
 137
 138     url_fseek(s->pb, off, SEEK_SET);
 139     mpc8_get_chunk_header(s->pb, &tag, &size);
 140     if(tag != TAG_SEEKTABLE){
 141         av_log(s, AV_LOG_ERROR, "No seek table at given position\n");
 142         return;
 143     }
 144     if(!(buf = av_malloc(size + FF_INPUT_BUFFER_PADDING_SIZE)))
 145         return;
 146     get_buffer(s->pb, buf, size);
 147     init_get_bits(&gb, buf, size * 8);
 148     size = gb_get_v(&gb);
 149     if(size > UINT_MAX/4 || size > c->samples/1152){
 150         av_log(s, AV_LOG_ERROR, "Seek table is too big\n");
 151         return;
 152     }
 153     seekd = get_bits(&gb, 4);
 154     for(i = 0; i < 2; i++){
 155         pos = gb_get_v(&gb) + c->header_pos;
 156         ppos[1 - i] = pos;
 157         av_add_index_entry(s->streams[0], pos, i, 0, 0, AVINDEX_KEYFRAME);
 158     }
 159     for(; i < size; i++){
 160         t = get_unary(&gb, 1, 33) << 12;
 161         t += get_bits(&gb, 12);
 162         if(t & 1)
 163             t = -(t & ~1);
 164         pos = (t >> 1) + ppos[0]*2 - ppos[1];
 165         av_add_index_entry(s->streams[0], pos, i << seekd, 0, 0, AVINDEX_KEYFRAME);
 166         ppos[1] = ppos[0];
 167         ppos[0] = pos;
 168     }
 169     av_free(buf);
 170 }
 171
 172 static void mpc8_handle_chunk(AVFormatContext *s, int tag, int64_t chunk_pos, int64_t size)
 173 {
 174     ByteIOContext *pb = s->pb;
 175     int64_t pos, off;
 176
 177     switch(tag){
 178     case TAG_SEEKTBLOFF:
 179         pos = url_ftell(pb) + size;
 180         off = ff_get_v(pb);
 181         mpc8_parse_seektable(s, chunk_pos + off);
 182         url_fseek(pb, pos, SEEK_SET);
 183         break;
 184     default:
 185         url_fskip(pb, size);
 186     }
 187 }
 188
 189 static int mpc8_read_header(AVFormatContext *s, AVFormatParameters *ap)
 190 {
 191     MPCContext *c = s->priv_data;
 192     ByteIOContext *pb = s->pb;
 193     AVStream *st;
 194     int tag = 0;
 195     int64_t size, pos;
 196
 197     c->header_pos = url_ftell(pb);
 198     if(get_le32(pb) != TAG_MPCK){
 199         av_log(s, AV_LOG_ERROR, "Not a Musepack8 file\n");
 200         return -1;
 201     }
 202
 203     while(!url_feof(pb)){
 204         pos = url_ftell(pb);
 205         mpc8_get_chunk_header(pb, &tag, &size);
 206         if(tag == TAG_STREAMHDR)
 207             break;
 208         mpc8_handle_chunk(s, tag, pos, size);
 209     }
 210     if(tag != TAG_STREAMHDR){
 211         av_log(s, AV_LOG_ERROR, "Stream header not found\n");
 212         return -1;
 213     }
 214     pos = url_ftell(pb);
 215     url_fskip(pb, 4); //CRC
 216     c->ver = get_byte(pb);
 217     if(c->ver != 8){
 218         av_log(s, AV_LOG_ERROR, "Unknown stream version %d\n", c->ver);
 219         return -1;
 220     }
 221     c->samples = ff_get_v(pb);
 222     ff_get_v(pb); //silence samples at the beginning
 223
 224     st = av_new_stream(s, 0);
 225     if (!st)
 226         return AVERROR(ENOMEM);
 227     st->codec->codec_type = CODEC_TYPE_AUDIO;
 228     st->codec->codec_id = CODEC_ID_MUSEPACK8;
 229     st->codec->bits_per_coded_sample = 16;
 230
 231     st->codec->extradata_size = 2;
 232     st->codec->extradata = av_mallocz(st->codec->extradata_size + FF_INPUT_BUFFER_PADDING_SIZE);
 233     get_buffer(pb, st->codec->extradata, st->codec->extradata_size);
 234
 235     st->codec->channels = (st->codec->extradata[1] >> 4) + 1;
 236     st->codec->sample_rate = mpc8_rate[st->codec->extradata[0] >> 5];
 237     av_set_pts_info(st, 32, 1152  << (st->codec->extradata[1]&3)*2, st->codec->sample_rate);
 238     st->duration = c->samples / (1152 << (st->codec->extradata[1]&3)*2);
 239     size -= url_ftell(pb) - pos;
 240
 241     return 0;
 242 }
 243
 244 static int mpc8_read_packet(AVFormatContext *s, AVPacket *pkt)
 245 {
 246     MPCContext *c = s->priv_data;
 247     int tag;
 248     int64_t pos, size;
 249
 250     while(!url_feof(s->pb)){
 251         pos = url_ftell(s->pb);
 252         mpc8_get_chunk_header(s->pb, &tag, &size);
 253         if (size < 0)
 254             return -1;
 255         if(tag == TAG_AUDIOPACKET){
 256             if(av_get_packet(s->pb, pkt, size) < 0)
 257                 return AVERROR(ENOMEM);
 258             pkt->stream_index = 0;
 259             pkt->pts = c->frame;
 260             return 0;
 261         }
 262         if(tag == TAG_STREAMEND)
 263             return AVERROR(EIO);
 264         mpc8_handle_chunk(s, tag, pos, size);
 265     }
 266     return 0;
 267 }
 268
 269 static int mpc8_read_seek(AVFormatContext *s, int stream_index, int64_t timestamp, int flags)
 270 {
 271     AVStream *st = s->streams[stream_index];
 272     MPCContext *c = s->priv_data;
 273     int index = av_index_search_timestamp(st, timestamp, flags);
 274
 275     if(index < 0) return -1;
 276     url_fseek(s->pb, st->index_entries[index].pos, SEEK_SET);
 277     c->frame = st->index_entries[index].timestamp;
 278     return 0;
 279 }
 280
 281
 282 AVInputFormat mpc8_demuxer = {
 283     "mpc8",
 284     NULL_IF_CONFIG_SMALL("Musepack SV8"),
 285     sizeof(MPCContext),
 286     mpc8_probe,
 287     mpc8_read_header,
 288     mpc8_read_packet,
 289     NULL,
 290     mpc8_read_seek,
 291 };