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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 
29 /// Two-byte MPC tag
30 #define MKMPCTAG(a, b) (a | (b << 8))
31 
32 #define TAG_MPCK MKTAG('M','P','C','K')
33 
34 /// Reserved MPC tags
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  int64_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 (bs + size - 2 >= bs_end)
95  return AVPROBE_SCORE_EXTENSION - 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  int64_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, ret;
140  GetBitContext gb;
141 
142  if (s->nb_streams == 0) {
143  av_log(s, AV_LOG_ERROR, "No stream added before parsing seek table\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, "Bad seek table size\n");
155  return;
156  }
157  if(!(buf = av_malloc(size + FF_INPUT_BUFFER_PADDING_SIZE)))
158  return;
159  ret = avio_read(s->pb, buf, size);
160  if (ret != size) {
161  av_log(s, AV_LOG_ERROR, "seek table truncated\n");
162  av_free(buf);
163  return;
164  }
165  memset(buf+size, 0, FF_INPUT_BUFFER_PADDING_SIZE);
166 
167  init_get_bits(&gb, buf, size * 8);
168  size = gb_get_v(&gb);
169  if(size > UINT_MAX/4 || size > c->samples/1152){
170  av_log(s, AV_LOG_ERROR, "Seek table is too big\n");
171  return;
172  }
173  seekd = get_bits(&gb, 4);
174  for(i = 0; i < 2; i++){
175  pos = gb_get_v(&gb) + c->header_pos;
176  ppos[1 - i] = pos;
177  av_add_index_entry(s->streams[0], pos, i, 0, 0, AVINDEX_KEYFRAME);
178  }
179  for(; i < size; i++){
180  t = get_unary(&gb, 1, 33) << 12;
181  t += get_bits(&gb, 12);
182  if(t & 1)
183  t = -(t & ~1);
184  pos = (t >> 1) + ppos[0]*2 - ppos[1];
185  av_add_index_entry(s->streams[0], pos, i << seekd, 0, 0, AVINDEX_KEYFRAME);
186  ppos[1] = ppos[0];
187  ppos[0] = pos;
188  }
189  av_free(buf);
190 }
191 
192 static void mpc8_handle_chunk(AVFormatContext *s, int tag, int64_t chunk_pos, int64_t size)
193 {
194  AVIOContext *pb = s->pb;
195  int64_t pos, off;
196 
197  switch(tag){
198  case TAG_SEEKTBLOFF:
199  pos = avio_tell(pb) + size;
200  off = ffio_read_varlen(pb);
201  mpc8_parse_seektable(s, chunk_pos + off);
202  avio_seek(pb, pos, SEEK_SET);
203  break;
204  default:
205  avio_skip(pb, size);
206  }
207 }
208 
210 {
211  MPCContext *c = s->priv_data;
212  AVIOContext *pb = s->pb;
213  AVStream *st;
214  int tag = 0;
215  int64_t size, pos;
216 
217  c->header_pos = avio_tell(pb);
218  if(avio_rl32(pb) != TAG_MPCK){
219  av_log(s, AV_LOG_ERROR, "Not a Musepack8 file\n");
220  return AVERROR_INVALIDDATA;
221  }
222 
223  while(!url_feof(pb)){
224  pos = avio_tell(pb);
225  mpc8_get_chunk_header(pb, &tag, &size);
226  if(tag == TAG_STREAMHDR)
227  break;
228  mpc8_handle_chunk(s, tag, pos, size);
229  }
230  if(tag != TAG_STREAMHDR){
231  av_log(s, AV_LOG_ERROR, "Stream header not found\n");
232  return AVERROR_INVALIDDATA;
233  }
234  pos = avio_tell(pb);
235  avio_skip(pb, 4); //CRC
236  c->ver = avio_r8(pb);
237  if(c->ver != 8){
238  av_log(s, AV_LOG_ERROR, "Unknown stream version %d\n", c->ver);
239  return AVERROR_PATCHWELCOME;
240  }
241  c->samples = ffio_read_varlen(pb);
242  ffio_read_varlen(pb); //silence samples at the beginning
243 
244  st = avformat_new_stream(s, NULL);
245  if (!st)
246  return AVERROR(ENOMEM);
249  st->codec->bits_per_coded_sample = 16;
250 
251  if (ff_get_extradata(st->codec, pb, 2) < 0)
252  return AVERROR(ENOMEM);
253 
254  st->codec->channels = (st->codec->extradata[1] >> 4) + 1;
255  st->codec->sample_rate = mpc8_rate[st->codec->extradata[0] >> 5];
256  avpriv_set_pts_info(st, 32, 1152 << (st->codec->extradata[1]&3)*2, st->codec->sample_rate);
257  st->start_time = 0;
258  st->duration = c->samples / (1152 << (st->codec->extradata[1]&3)*2);
259  size -= avio_tell(pb) - pos;
260  if (size > 0)
261  avio_skip(pb, size);
262 
263  if (pb->seekable) {
264  int64_t pos = avio_tell(s->pb);
266  avio_seek(s->pb, pos, SEEK_SET);
267  }
268 
269  return 0;
270 }
271 
273 {
274  MPCContext *c = s->priv_data;
275  int tag;
276  int64_t pos, size;
277 
278  while(!url_feof(s->pb)){
279  pos = avio_tell(s->pb);
280 
281  /* don't return bogus packets with the ape tag data */
282  if (c->apetag_start && pos >= c->apetag_start)
283  return AVERROR_EOF;
284 
285  mpc8_get_chunk_header(s->pb, &tag, &size);
286  if (size < 0)
287  return -1;
288  if(tag == TAG_AUDIOPACKET){
289  if(av_get_packet(s->pb, pkt, size) < 0)
290  return AVERROR(ENOMEM);
291  pkt->stream_index = 0;
292  pkt->duration = 1;
293  return 0;
294  }
295  if(tag == TAG_STREAMEND)
296  return AVERROR(EIO);
297  mpc8_handle_chunk(s, tag, pos, size);
298  }
299  return AVERROR_EOF;
300 }
301 
302 static int mpc8_read_seek(AVFormatContext *s, int stream_index, int64_t timestamp, int flags)
303 {
304  AVStream *st = s->streams[stream_index];
305  int index = av_index_search_timestamp(st, timestamp, flags);
306 
307  if(index < 0) return -1;
308  if (avio_seek(s->pb, st->index_entries[index].pos, SEEK_SET) < 0)
309  return -1;
310  ff_update_cur_dts(s, st, st->index_entries[index].timestamp);
311  return 0;
312 }
313 
314 
316  .name = "mpc8",
317  .long_name = NULL_IF_CONFIG_SMALL("Musepack SV8"),
318  .priv_data_size = sizeof(MPCContext),
323 };