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 int mpc8_probe(AVProbeData *p)
  55 {
  56     if (AV_RL32(p->buf) == TAG_MPCK)
  57         return AVPROBE_SCORE_MAX;
  58     return 0;
  59 }
  60
  61 static inline int64_t gb_get_v(GetBitContext *gb)
  62 {
  63     int64_t v = 0;
  64     int bits = 0;
  65     while(get_bits1(gb) && bits < 64-7){
  66         v <<= 7;
  67         v |= get_bits(gb, 7);
  68         bits += 7;
  69     }
  70     v <<= 7;
  71     v |= get_bits(gb, 7);
  72
  73     return v;
  74 }
  75
  76 static void mpc8_get_chunk_header(ByteIOContext *pb, int *tag, int64_t *size)
  77 {
  78     int64_t pos;
  79     pos = url_ftell(pb);
  80     *tag = get_le16(pb);
  81     *size = ff_get_v(pb);
  82     *size -= url_ftell(pb) - pos;
  83 }
  84
  85 static void mpc8_parse_seektable(AVFormatContext *s, int64_t off)
  86 {
  87     MPCContext *c = s->priv_data;
  88     int tag;
  89     int64_t size, pos, ppos[2];
  90     uint8_t *buf;
  91     int i, t, seekd;
  92     GetBitContext gb;
  93
  94     url_fseek(s->pb, off, SEEK_SET);
  95     mpc8_get_chunk_header(s->pb, &tag, &size);
  96     if(tag != TAG_SEEKTABLE){
  97         av_log(s, AV_LOG_ERROR, "No seek table at given position\n");
  98         return;
  99     }
 100     if(!(buf = av_malloc(size)))
 101         return;
 102     get_buffer(s->pb, buf, size);
 103     init_get_bits(&gb, buf, size * 8);
 104     size = gb_get_v(&gb);
 105     if(size > UINT_MAX/4 || size > c->samples/1152){
 106         av_log(s, AV_LOG_ERROR, "Seek table is too big\n");
 107         return;
 108     }
 109     seekd = get_bits(&gb, 4);
 110     for(i = 0; i < 2; i++){
 111         pos = gb_get_v(&gb) + c->header_pos;
 112         ppos[1 - i] = pos;
 113         av_add_index_entry(s->streams[0], pos, i, 0, 0, AVINDEX_KEYFRAME);
 114     }
 115     for(; i < size; i++){
 116         t = get_unary(&gb, 1, 33) << 12;
 117         t += get_bits(&gb, 12);
 118         if(t & 1)
 119             t = -(t & ~1);
 120         pos = (t >> 1) + ppos[0]*2 - ppos[1];
 121         av_add_index_entry(s->streams[0], pos, i << seekd, 0, 0, AVINDEX_KEYFRAME);
 122         ppos[1] = ppos[0];
 123         ppos[0] = pos;
 124     }
 125     av_free(buf);
 126 }
 127
 128 static void mpc8_handle_chunk(AVFormatContext *s, int tag, int64_t chunk_pos, int64_t size)
 129 {
 130     ByteIOContext *pb = s->pb;
 131     int64_t pos, off;
 132
 133     switch(tag){
 134     case TAG_SEEKTBLOFF:
 135         pos = url_ftell(pb) + size;
 136         off = ff_get_v(pb);
 137         mpc8_parse_seektable(s, chunk_pos + off);
 138         url_fseek(pb, pos, SEEK_SET);
 139         break;
 140     default:
 141         url_fskip(pb, size);
 142     }
 143 }
 144
 145 static int mpc8_read_header(AVFormatContext *s, AVFormatParameters *ap)
 146 {
 147     MPCContext *c = s->priv_data;
 148     ByteIOContext *pb = s->pb;
 149     AVStream *st;
 150     int tag = 0;
 151     int64_t size, pos;
 152
 153     c->header_pos = url_ftell(pb);
 154     if(get_le32(pb) != TAG_MPCK){
 155         av_log(s, AV_LOG_ERROR, "Not a Musepack8 file\n");
 156         return -1;
 157     }
 158
 159     while(!url_feof(pb)){
 160         pos = url_ftell(pb);
 161         mpc8_get_chunk_header(pb, &tag, &size);
 162         if(tag == TAG_STREAMHDR)
 163             break;
 164         mpc8_handle_chunk(s, tag, pos, size);
 165     }
 166     if(tag != TAG_STREAMHDR){
 167         av_log(s, AV_LOG_ERROR, "Stream header not found\n");
 168         return -1;
 169     }
 170     pos = url_ftell(pb);
 171     url_fskip(pb, 4); //CRC
 172     c->ver = get_byte(pb);
 173     if(c->ver != 8){
 174         av_log(s, AV_LOG_ERROR, "Unknown stream version %d\n", c->ver);
 175         return -1;
 176     }
 177     c->samples = ff_get_v(pb);
 178     ff_get_v(pb); //silence samples at the beginning
 179
 180     st = av_new_stream(s, 0);
 181     if (!st)
 182         return AVERROR(ENOMEM);
 183     st->codec->codec_type = CODEC_TYPE_AUDIO;
 184     st->codec->codec_id = CODEC_ID_MUSEPACK8;
 185     st->codec->bits_per_coded_sample = 16;
 186
 187     st->codec->extradata_size = 2;
 188     st->codec->extradata = av_mallocz(st->codec->extradata_size + FF_INPUT_BUFFER_PADDING_SIZE);
 189     get_buffer(pb, st->codec->extradata, st->codec->extradata_size);
 190
 191     st->codec->channels = (st->codec->extradata[1] >> 4) + 1;
 192     st->codec->sample_rate = mpc8_rate[st->codec->extradata[0] >> 5];
 193     av_set_pts_info(st, 32, 1152  << (st->codec->extradata[1]&3)*2, st->codec->sample_rate);
 194     st->duration = c->samples / (1152 << (st->codec->extradata[1]&3)*2);
 195     size -= url_ftell(pb) - pos;
 196
 197     return 0;
 198 }
 199
 200 static int mpc8_read_packet(AVFormatContext *s, AVPacket *pkt)
 201 {
 202     MPCContext *c = s->priv_data;
 203     int tag;
 204     int64_t pos, size;
 205
 206     while(!url_feof(s->pb)){
 207         pos = url_ftell(s->pb);
 208         mpc8_get_chunk_header(s->pb, &tag, &size);
 209         if(tag == TAG_AUDIOPACKET){
 210             if(av_get_packet(s->pb, pkt, size) < 0)
 211                 return AVERROR(ENOMEM);
 212             pkt->stream_index = 0;
 213             pkt->pts = c->frame;
 214             return 0;
 215         }
 216         if(tag == TAG_STREAMEND)
 217             return AVERROR(EIO);
 218         mpc8_handle_chunk(s, tag, pos, size);
 219     }
 220     return 0;
 221 }
 222
 223 static int mpc8_read_seek(AVFormatContext *s, int stream_index, int64_t timestamp, int flags)
 224 {
 225     AVStream *st = s->streams[stream_index];
 226     MPCContext *c = s->priv_data;
 227     int index = av_index_search_timestamp(st, timestamp, flags);
 228
 229     if(index < 0) return -1;
 230     url_fseek(s->pb, st->index_entries[index].pos, SEEK_SET);
 231     c->frame = st->index_entries[index].timestamp;
 232     return 0;
 233 }
 234
 235
 236 AVInputFormat mpc8_demuxer = {
 237     "mpc8",
 238     NULL_IF_CONFIG_SMALL("Musepack SV8"),
 239     sizeof(MPCContext),
 240     mpc8_probe,
 241     mpc8_read_header,
 242     mpc8_read_packet,
 243     NULL,
 244     mpc8_read_seek,
 245 };