FFmpeg  1.2.12
mpc8.c
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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 "apetag.h"
25 #include "avformat.h"
26 #include "internal.h"
27 #include "avio_internal.h"
28 
30 #define MKMPCTAG(a, b) (a | (b << 8))
31 
32 #define TAG_MPCK MKTAG('M','P','C','K')
33 
36  TAG_STREAMHDR = MKMPCTAG('S','H'),
37  TAG_STREAMEND = MKMPCTAG('S','E'),
38 
40 
42  TAG_SEEKTABLE = MKMPCTAG('S','T'),
43 
45  TAG_ENCINFO = MKMPCTAG('E','I'),
46 };
47 
48 static const int mpc8_rate[8] = { 44100, 48000, 37800, 32000, -1, -1, -1, -1 };
49 
50 typedef struct {
51  int ver;
52  int64_t header_pos;
53  int64_t samples;
54 
55  int64_t apetag_start;
56 } MPCContext;
57 
58 static inline int64_t bs_get_v(const uint8_t **bs)
59 {
60  uint64_t v = 0;
61  int br = 0;
62  int c;
63 
64  do {
65  c = **bs; (*bs)++;
66  v <<= 7;
67  v |= c & 0x7F;
68  br++;
69  if (br > 10)
70  return -1;
71  } while (c & 0x80);
72 
73  return v - br;
74 }
75 
76 static int mpc8_probe(AVProbeData *p)
77 {
78  const uint8_t *bs = p->buf + 4;
79  const uint8_t *bs_end = bs + p->buf_size;
80  int64_t size;
81 
82  if (p->buf_size < 16)
83  return 0;
84  if (AV_RL32(p->buf) != TAG_MPCK)
85  return 0;
86  while (bs < bs_end + 3) {
87  int header_found = (bs[0] == 'S' && bs[1] == 'H');
88  if (bs[0] < 'A' || bs[0] > 'Z' || bs[1] < 'A' || bs[1] > 'Z')
89  return 0;
90  bs += 2;
91  size = bs_get_v(&bs);
92  if (size < 2)
93  return 0;
94  if (size >= bs_end - bs + 2)
95  return AVPROBE_SCORE_MAX / 4 - 1; //seems to be valid MPC but no header yet
96  if (header_found) {
97  if (size < 11 || size > 28)
98  return 0;
99  if (!AV_RL32(bs)) //zero CRC is invalid
100  return 0;
101  return AVPROBE_SCORE_MAX;
102  } else {
103  bs += size - 2;
104  }
105  }
106  return 0;
107 }
108 
109 static inline int64_t gb_get_v(GetBitContext *gb)
110 {
111  uint64_t v = 0;
112  int bits = 0;
113  while(get_bits1(gb) && bits < 64-7){
114  v <<= 7;
115  v |= get_bits(gb, 7);
116  bits += 7;
117  }
118  v <<= 7;
119  v |= get_bits(gb, 7);
120 
121  return v;
122 }
123 
124 static void mpc8_get_chunk_header(AVIOContext *pb, int *tag, int64_t *size)
125 {
126  int64_t pos;
127  pos = avio_tell(pb);
128  *tag = avio_rl16(pb);
129  *size = ffio_read_varlen(pb);
130  *size -= avio_tell(pb) - pos;
131 }
132 
133 static void mpc8_parse_seektable(AVFormatContext *s, int64_t off)
134 {
135  MPCContext *c = s->priv_data;
136  int tag;
137  int64_t size, pos, ppos[2];
138  uint8_t *buf;
139  int i, t, seekd;
140  GetBitContext gb;
141 
142  if (s->nb_streams<=0) {
143  av_log(s, AV_LOG_ERROR, "cannot parse stream table before stream header\n");
144  return;
145  }
146 
147  avio_seek(s->pb, off, SEEK_SET);
148  mpc8_get_chunk_header(s->pb, &tag, &size);
149  if(tag != TAG_SEEKTABLE){
150  av_log(s, AV_LOG_ERROR, "No seek table at given position\n");
151  return;
152  }
153  if (size > INT_MAX/10 || size<=0) {
154  av_log(s, AV_LOG_ERROR, "Seek table size is invalid\n");
155  return;
156  }
157  if(!(buf = av_malloc(size + FF_INPUT_BUFFER_PADDING_SIZE)))
158  return;
159  avio_read(s->pb, buf, size);
160  init_get_bits(&gb, buf, size * 8);
161  size = gb_get_v(&gb);
162  if(size > UINT_MAX/4 || size > c->samples/1152){
163  av_log(s, AV_LOG_ERROR, "Seek table is too big\n");
164  return;
165  }
166  seekd = get_bits(&gb, 4);
167  for(i = 0; i < 2; i++){
168  pos = gb_get_v(&gb) + c->header_pos;
169  ppos[1 - i] = pos;
170  av_add_index_entry(s->streams[0], pos, i, 0, 0, AVINDEX_KEYFRAME);
171  }
172  for(; i < size; i++){
173  t = get_unary(&gb, 1, 33) << 12;
174  t += get_bits(&gb, 12);
175  if(t & 1)
176  t = -(t & ~1);
177  pos = (t >> 1) + ppos[0]*2 - ppos[1];
178  av_add_index_entry(s->streams[0], pos, i << seekd, 0, 0, AVINDEX_KEYFRAME);
179  ppos[1] = ppos[0];
180  ppos[0] = pos;
181  }
182  av_free(buf);
183 }
184 
185 static void mpc8_handle_chunk(AVFormatContext *s, int tag, int64_t chunk_pos, int64_t size)
186 {
187  AVIOContext *pb = s->pb;
188  int64_t pos, off;
189 
190  switch(tag){
191  case TAG_SEEKTBLOFF:
192  pos = avio_tell(pb) + size;
193  off = ffio_read_varlen(pb);
194  mpc8_parse_seektable(s, chunk_pos + off);
195  avio_seek(pb, pos, SEEK_SET);
196  break;
197  default:
198  avio_skip(pb, size);
199  }
200 }
201 
203 {
204  MPCContext *c = s->priv_data;
205  AVIOContext *pb = s->pb;
206  AVStream *st;
207  int tag = 0;
208  int64_t size, pos;
209 
210  c->header_pos = avio_tell(pb);
211  if(avio_rl32(pb) != TAG_MPCK){
212  av_log(s, AV_LOG_ERROR, "Not a Musepack8 file\n");
213  return AVERROR_INVALIDDATA;
214  }
215 
216  while(!url_feof(pb)){
217  pos = avio_tell(pb);
218  mpc8_get_chunk_header(pb, &tag, &size);
219  if (size < 0) {
220  av_log(s, AV_LOG_ERROR, "Invalid chunk length\n");
221  return AVERROR_INVALIDDATA;
222  }
223  if(tag == TAG_STREAMHDR)
224  break;
225  mpc8_handle_chunk(s, tag, pos, size);
226  }
227  if(tag != TAG_STREAMHDR){
228  av_log(s, AV_LOG_ERROR, "Stream header not found\n");
229  return AVERROR_INVALIDDATA;
230  }
231  pos = avio_tell(pb);
232  avio_skip(pb, 4); //CRC
233  c->ver = avio_r8(pb);
234  if(c->ver != 8){
235  av_log(s, AV_LOG_ERROR, "Unknown stream version %d\n", c->ver);
236  return AVERROR_PATCHWELCOME;
237  }
238  c->samples = ffio_read_varlen(pb);
239  ffio_read_varlen(pb); //silence samples at the beginning
240 
241  st = avformat_new_stream(s, NULL);
242  if (!st)
243  return AVERROR(ENOMEM);
246  st->codec->bits_per_coded_sample = 16;
247 
248  st->codec->extradata_size = 2;
250  avio_read(pb, st->codec->extradata, st->codec->extradata_size);
251 
252  st->codec->channels = (st->codec->extradata[1] >> 4) + 1;
253  st->codec->sample_rate = mpc8_rate[st->codec->extradata[0] >> 5];
254  avpriv_set_pts_info(st, 32, 1152 << (st->codec->extradata[1]&3)*2, st->codec->sample_rate);
255  st->start_time = 0;
256  st->duration = c->samples / (1152 << (st->codec->extradata[1]&3)*2);
257  size -= avio_tell(pb) - pos;
258  if (size > 0)
259  avio_skip(pb, size);
260 
261  if (pb->seekable) {
262  int64_t pos = avio_tell(s->pb);
264  avio_seek(s->pb, pos, SEEK_SET);
265  }
266 
267  return 0;
268 }
269 
271 {
272  MPCContext *c = s->priv_data;
273  int tag;
274  int64_t pos, size;
275 
276  while(!url_feof(s->pb)){
277  pos = avio_tell(s->pb);
278 
279  /* don't return bogus packets with the ape tag data */
280  if (c->apetag_start && pos >= c->apetag_start)
281  return AVERROR_EOF;
282 
283  mpc8_get_chunk_header(s->pb, &tag, &size);
284  if (size < 0)
285  return -1;
286  if(tag == TAG_AUDIOPACKET){
287  if(av_get_packet(s->pb, pkt, size) < 0)
288  return AVERROR(ENOMEM);
289  pkt->stream_index = 0;
290  pkt->duration = 1;
291  return 0;
292  }
293  if(tag == TAG_STREAMEND)
294  return AVERROR(EIO);
295  mpc8_handle_chunk(s, tag, pos, size);
296  }
297  return AVERROR_EOF;
298 }
299 
300 static int mpc8_read_seek(AVFormatContext *s, int stream_index, int64_t timestamp, int flags)
301 {
302  AVStream *st = s->streams[stream_index];
303  int index = av_index_search_timestamp(st, timestamp, flags);
304 
305  if(index < 0) return -1;
306  if (avio_seek(s->pb, st->index_entries[index].pos, SEEK_SET) < 0)
307  return -1;
308  ff_update_cur_dts(s, st, st->index_entries[index].timestamp);
309  return 0;
310 }
311 
312 
314  .name = "mpc8",
315  .long_name = NULL_IF_CONFIG_SMALL("Musepack SV8"),
316  .priv_data_size = sizeof(MPCContext),
321 };