mpc.c
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1 /*
2  * Musepack demuxer
3  * Copyright (c) 2006 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 "avformat.h"
24 #include "internal.h"
25 #include "apetag.h"
26 #include "id3v1.h"
27 #include "libavutil/dict.h"
28 
29 #define MPC_FRAMESIZE 1152
30 #define DELAY_FRAMES 32
31 
32 static const int mpc_rate[4] = { 44100, 48000, 37800, 32000 };
33 typedef struct {
34  int64_t pos;
35  int size, skip;
36 }MPCFrame;
37 
38 typedef struct {
39  int ver;
40  uint32_t curframe, lastframe;
41  uint32_t fcount;
43  int curbits;
45 } MPCContext;
46 
47 static int mpc_probe(AVProbeData *p)
48 {
49  const uint8_t *d = p->buf;
50  if (d[0] == 'M' && d[1] == 'P' && d[2] == '+' && (d[3] == 0x17 || d[3] == 0x7))
51  return AVPROBE_SCORE_MAX;
52  return 0;
53 }
54 
56 {
57  MPCContext *c = s->priv_data;
58  AVStream *st;
59 
60  if(avio_rl24(s->pb) != MKTAG('M', 'P', '+', 0)){
61  av_log(s, AV_LOG_ERROR, "Not a Musepack file\n");
62  return -1;
63  }
64  c->ver = avio_r8(s->pb);
65  if(c->ver != 0x07 && c->ver != 0x17){
66  av_log(s, AV_LOG_ERROR, "Can demux Musepack SV7, got version %02X\n", c->ver);
67  return -1;
68  }
69  c->fcount = avio_rl32(s->pb);
70  if((int64_t)c->fcount * sizeof(MPCFrame) >= UINT_MAX){
71  av_log(s, AV_LOG_ERROR, "Too many frames, seeking is not possible\n");
72  return -1;
73  }
74  if(c->fcount){
75  c->frames = av_malloc(c->fcount * sizeof(MPCFrame));
76  if(!c->frames){
77  av_log(s, AV_LOG_ERROR, "Cannot allocate seektable\n");
78  return AVERROR(ENOMEM);
79  }
80  }else{
81  av_log(s, AV_LOG_WARNING, "Container reports no frames\n");
82  }
83  c->curframe = 0;
84  c->lastframe = -1;
85  c->curbits = 8;
86  c->frames_noted = 0;
87 
88  st = avformat_new_stream(s, NULL);
89  if (!st)
90  return AVERROR(ENOMEM);
93  st->codec->channels = 2;
94  st->codec->bits_per_coded_sample = 16;
95 
96  st->codec->extradata_size = 16;
98  avio_read(s->pb, st->codec->extradata, 16);
99  st->codec->sample_rate = mpc_rate[st->codec->extradata[2] & 3];
101  /* scan for seekpoints */
102  st->start_time = 0;
103  st->duration = c->fcount;
104 
105  /* try to read APE tags */
106  if (s->pb->seekable) {
107  int64_t pos = avio_tell(s->pb);
108  ff_ape_parse_tag(s);
110  ff_id3v1_read(s);
111  avio_seek(s->pb, pos, SEEK_SET);
112  }
113 
114  return 0;
115 }
116 
118 {
119  MPCContext *c = s->priv_data;
120  int ret, size, size2, curbits, cur = c->curframe;
121  unsigned tmp;
122  int64_t pos;
123 
124  if (c->curframe >= c->fcount && c->fcount)
125  return -1;
126 
127  if(c->curframe != c->lastframe + 1){
128  avio_seek(s->pb, c->frames[c->curframe].pos, SEEK_SET);
129  c->curbits = c->frames[c->curframe].skip;
130  }
131  c->lastframe = c->curframe;
132  c->curframe++;
133  curbits = c->curbits;
134  pos = avio_tell(s->pb);
135  tmp = avio_rl32(s->pb);
136  if(curbits <= 12){
137  size2 = (tmp >> (12 - curbits)) & 0xFFFFF;
138  }else{
139  size2 = (tmp << (curbits - 12) | avio_rl32(s->pb) >> (44 - curbits)) & 0xFFFFF;
140  }
141  curbits += 20;
142  avio_seek(s->pb, pos, SEEK_SET);
143 
144  size = ((size2 + curbits + 31) & ~31) >> 3;
145  if(cur == c->frames_noted && c->fcount){
146  c->frames[cur].pos = pos;
147  c->frames[cur].size = size;
148  c->frames[cur].skip = curbits - 20;
149  av_add_index_entry(s->streams[0], cur, cur, size, 0, AVINDEX_KEYFRAME);
150  c->frames_noted++;
151  }
152  c->curbits = (curbits + size2) & 0x1F;
153 
154  if (av_new_packet(pkt, size) < 0)
155  return AVERROR(EIO);
156 
157  pkt->data[0] = curbits;
158  pkt->data[1] = (c->curframe > c->fcount) && c->fcount;
159  pkt->data[2] = 0;
160  pkt->data[3] = 0;
161 
162  pkt->stream_index = 0;
163  pkt->pts = cur;
164  ret = avio_read(s->pb, pkt->data + 4, size);
165  if(c->curbits)
166  avio_seek(s->pb, -4, SEEK_CUR);
167  if(ret < size){
168  av_free_packet(pkt);
169  return AVERROR(EIO);
170  }
171  pkt->size = ret + 4;
172 
173  return 0;
174 }
175 
177 {
178  MPCContext *c = s->priv_data;
179 
180  av_freep(&c->frames);
181  return 0;
182 }
183 
191 static int mpc_read_seek(AVFormatContext *s, int stream_index, int64_t timestamp, int flags)
192 {
193  AVStream *st = s->streams[stream_index];
194  MPCContext *c = s->priv_data;
195  AVPacket pkt1, *pkt = &pkt1;
196  int ret;
197  int index = av_index_search_timestamp(st, timestamp - DELAY_FRAMES, flags);
198  uint32_t lastframe;
199 
200  /* if found, seek there */
201  if (index >= 0){
202  c->curframe = st->index_entries[index].pos;
203  return 0;
204  }
205  /* if timestamp is out of bounds, return error */
206  if(timestamp < 0 || timestamp >= c->fcount)
207  return -1;
208  timestamp -= DELAY_FRAMES;
209  /* seek to the furthest known position and read packets until
210  we reach desired position */
211  lastframe = c->curframe;
212  if(c->frames_noted) c->curframe = c->frames_noted - 1;
213  while(c->curframe < timestamp){
214  ret = av_read_frame(s, pkt);
215  if (ret < 0){
216  c->curframe = lastframe;
217  return -1;
218  }
219  av_free_packet(pkt);
220  }
221  return 0;
222 }
223 
224 
226  .name = "mpc",
227  .long_name = NULL_IF_CONFIG_SMALL("Musepack"),
228  .priv_data_size = sizeof(MPCContext),
234  .extensions = "mpc",
235 };