mpc8.c
Go to the documentation of this file.
1 /*
2  * Musepack SV8 demuxer
3  * Copyright (c) 2007 Konstantin Shishkov
4  *
5  * This file is part of Libav.
6  *
7  * Libav 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  * Libav 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 Libav; 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 #include "internal.h"
26 #include "avio_internal.h"
27 
29 #define MKMPCTAG(a, b) (a | (b << 8))
30 
31 #define TAG_MPCK MKTAG('M','P','C','K')
32 
35  TAG_STREAMHDR = MKMPCTAG('S','H'),
36  TAG_STREAMEND = MKMPCTAG('S','E'),
37 
39 
41  TAG_SEEKTABLE = MKMPCTAG('S','T'),
42 
44  TAG_ENCINFO = MKMPCTAG('E','I'),
45 };
46 
47 static const int mpc8_rate[8] = { 44100, 48000, 37800, 32000, -1, -1, -1, -1 };
48 
49 typedef struct {
50  int ver;
51  int frame;
52  int64_t header_pos;
53  int64_t samples;
54 } MPCContext;
55 
56 static inline int64_t bs_get_v(uint8_t **bs)
57 {
58  int64_t v = 0;
59  int br = 0;
60  int c;
61 
62  do {
63  c = **bs; (*bs)++;
64  v <<= 7;
65  v |= c & 0x7F;
66  br++;
67  if (br > 10)
68  return -1;
69  } while (c & 0x80);
70 
71  return v - br;
72 }
73 
74 static int mpc8_probe(AVProbeData *p)
75 {
76  uint8_t *bs = p->buf + 4;
77  uint8_t *bs_end = bs + p->buf_size;
78  int64_t size;
79 
80  if (p->buf_size < 16)
81  return 0;
82  if (AV_RL32(p->buf) != TAG_MPCK)
83  return 0;
84  while (bs < bs_end + 3) {
85  int header_found = (bs[0] == 'S' && bs[1] == 'H');
86  if (bs[0] < 'A' || bs[0] > 'Z' || bs[1] < 'A' || bs[1] > 'Z')
87  return 0;
88  bs += 2;
89  size = bs_get_v(&bs);
90  if (size < 2)
91  return 0;
92  if (bs + size - 2 >= bs_end)
93  return AVPROBE_SCORE_MAX / 4 - 1; //seems to be valid MPC but no header yet
94  if (header_found) {
95  if (size < 11 || size > 28)
96  return 0;
97  if (!AV_RL32(bs)) //zero CRC is invalid
98  return 0;
99  return AVPROBE_SCORE_MAX;
100  } else {
101  bs += size - 2;
102  }
103  }
104  return 0;
105 }
106 
107 static inline int64_t gb_get_v(GetBitContext *gb)
108 {
109  int64_t v = 0;
110  int bits = 0;
111  while(get_bits1(gb) && bits < 64-7){
112  v <<= 7;
113  v |= get_bits(gb, 7);
114  bits += 7;
115  }
116  v <<= 7;
117  v |= get_bits(gb, 7);
118 
119  return v;
120 }
121 
122 static void mpc8_get_chunk_header(AVIOContext *pb, int *tag, int64_t *size)
123 {
124  int64_t pos;
125  pos = avio_tell(pb);
126  *tag = avio_rl16(pb);
127  *size = ffio_read_varlen(pb);
128  *size -= avio_tell(pb) - pos;
129 }
130 
131 static void mpc8_parse_seektable(AVFormatContext *s, int64_t off)
132 {
133  MPCContext *c = s->priv_data;
134  int tag;
135  int64_t size, pos, ppos[2];
136  uint8_t *buf;
137  int i, t, seekd;
138  GetBitContext gb;
139 
140  avio_seek(s->pb, off, SEEK_SET);
141  mpc8_get_chunk_header(s->pb, &tag, &size);
142  if(tag != TAG_SEEKTABLE){
143  av_log(s, AV_LOG_ERROR, "No seek table at given position\n");
144  return;
145  }
146  if(!(buf = av_malloc(size + FF_INPUT_BUFFER_PADDING_SIZE)))
147  return;
148  avio_read(s->pb, buf, size);
149  init_get_bits(&gb, buf, size * 8);
150  size = gb_get_v(&gb);
151  if(size > UINT_MAX/4 || size > c->samples/1152){
152  av_log(s, AV_LOG_ERROR, "Seek table is too big\n");
153  return;
154  }
155  seekd = get_bits(&gb, 4);
156  for(i = 0; i < 2; i++){
157  pos = gb_get_v(&gb) + c->header_pos;
158  ppos[1 - i] = pos;
159  av_add_index_entry(s->streams[0], pos, i, 0, 0, AVINDEX_KEYFRAME);
160  }
161  for(; i < size; i++){
162  t = get_unary(&gb, 1, 33) << 12;
163  t += get_bits(&gb, 12);
164  if(t & 1)
165  t = -(t & ~1);
166  pos = (t >> 1) + ppos[0]*2 - ppos[1];
167  av_add_index_entry(s->streams[0], pos, i << seekd, 0, 0, AVINDEX_KEYFRAME);
168  ppos[1] = ppos[0];
169  ppos[0] = pos;
170  }
171  av_free(buf);
172 }
173 
174 static void mpc8_handle_chunk(AVFormatContext *s, int tag, int64_t chunk_pos, int64_t size)
175 {
176  AVIOContext *pb = s->pb;
177  int64_t pos, off;
178 
179  switch(tag){
180  case TAG_SEEKTBLOFF:
181  pos = avio_tell(pb) + size;
182  off = ffio_read_varlen(pb);
183  mpc8_parse_seektable(s, chunk_pos + off);
184  avio_seek(pb, pos, SEEK_SET);
185  break;
186  default:
187  avio_skip(pb, size);
188  }
189 }
190 
192 {
193  MPCContext *c = s->priv_data;
194  AVIOContext *pb = s->pb;
195  AVStream *st;
196  int tag = 0;
197  int64_t size, pos;
198 
199  c->header_pos = avio_tell(pb);
200  if(avio_rl32(pb) != TAG_MPCK){
201  av_log(s, AV_LOG_ERROR, "Not a Musepack8 file\n");
202  return -1;
203  }
204 
205  while(!pb->eof_reached){
206  pos = avio_tell(pb);
207  mpc8_get_chunk_header(pb, &tag, &size);
208  if(tag == TAG_STREAMHDR)
209  break;
210  mpc8_handle_chunk(s, tag, pos, size);
211  }
212  if(tag != TAG_STREAMHDR){
213  av_log(s, AV_LOG_ERROR, "Stream header not found\n");
214  return -1;
215  }
216  pos = avio_tell(pb);
217  avio_skip(pb, 4); //CRC
218  c->ver = avio_r8(pb);
219  if(c->ver != 8){
220  av_log(s, AV_LOG_ERROR, "Unknown stream version %d\n", c->ver);
221  return -1;
222  }
223  c->samples = ffio_read_varlen(pb);
224  ffio_read_varlen(pb); //silence samples at the beginning
225 
226  st = avformat_new_stream(s, NULL);
227  if (!st)
228  return AVERROR(ENOMEM);
231  st->codec->bits_per_coded_sample = 16;
232 
233  st->codec->extradata_size = 2;
235  avio_read(pb, st->codec->extradata, st->codec->extradata_size);
236 
237  st->codec->channels = (st->codec->extradata[1] >> 4) + 1;
238  st->codec->sample_rate = mpc8_rate[st->codec->extradata[0] >> 5];
239  avpriv_set_pts_info(st, 32, 1152 << (st->codec->extradata[1]&3)*2, st->codec->sample_rate);
240  st->duration = c->samples / (1152 << (st->codec->extradata[1]&3)*2);
241  size -= avio_tell(pb) - pos;
242 
243  return 0;
244 }
245 
247 {
248  MPCContext *c = s->priv_data;
249  int tag;
250  int64_t pos, size;
251 
252  while(!s->pb->eof_reached){
253  pos = avio_tell(s->pb);
254  mpc8_get_chunk_header(s->pb, &tag, &size);
255  if (size < 0)
256  return -1;
257  if(tag == TAG_AUDIOPACKET){
258  if(av_get_packet(s->pb, pkt, size) < 0)
259  return AVERROR(ENOMEM);
260  pkt->stream_index = 0;
261  pkt->pts = c->frame;
262  return 0;
263  }
264  if(tag == TAG_STREAMEND)
265  return AVERROR(EIO);
266  mpc8_handle_chunk(s, tag, pos, size);
267  }
268  return AVERROR_EOF;
269 }
270 
271 static int mpc8_read_seek(AVFormatContext *s, int stream_index, int64_t timestamp, int flags)
272 {
273  AVStream *st = s->streams[stream_index];
274  MPCContext *c = s->priv_data;
275  int index = av_index_search_timestamp(st, timestamp, flags);
276 
277  if(index < 0) return -1;
278  avio_seek(s->pb, st->index_entries[index].pos, SEEK_SET);
280  return 0;
281 }
282 
283 
285  .name = "mpc8",
286  .long_name = NULL_IF_CONFIG_SMALL("Musepack SV8"),
287  .priv_data_size = sizeof(MPCContext),
292 };