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mpc.c
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1 /*
2  * Musepack demuxer
3  * Copyright (c) 2006 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 
23 #include "libavcodec/get_bits.h"
24 #include "avformat.h"
25 #include "internal.h"
26 #include "apetag.h"
27 #include "id3v1.h"
28 #include "libavutil/dict.h"
29 
30 #define MPC_FRAMESIZE 1152
31 #define DELAY_FRAMES 32
32 
33 static const int mpc_rate[4] = { 44100, 48000, 37800, 32000 };
34 typedef struct {
35  int64_t pos;
36  int size, skip;
37 }MPCFrame;
38 
39 typedef struct {
40  int ver;
41  uint32_t curframe, lastframe;
42  uint32_t fcount;
44  int curbits;
46 } MPCContext;
47 
48 static int mpc_probe(AVProbeData *p)
49 {
50  const uint8_t *d = p->buf;
51  if (d[0] == 'M' && d[1] == 'P' && d[2] == '+' && (d[3] == 0x17 || d[3] == 0x7))
52  return AVPROBE_SCORE_MAX;
53  return 0;
54 }
55 
57 {
58  MPCContext *c = s->priv_data;
59  AVStream *st;
60 
61  if(avio_rl24(s->pb) != MKTAG('M', 'P', '+', 0)){
62  av_log(s, AV_LOG_ERROR, "Not a Musepack file\n");
63  return AVERROR_INVALIDDATA;
64  }
65  c->ver = avio_r8(s->pb);
66  if(c->ver != 0x07 && c->ver != 0x17){
67  av_log(s, AV_LOG_ERROR, "Can demux Musepack SV7, got version %02X\n", c->ver);
68  return AVERROR_INVALIDDATA;
69  }
70  c->fcount = avio_rl32(s->pb);
71  if((int64_t)c->fcount * sizeof(MPCFrame) >= UINT_MAX){
72  av_log(s, AV_LOG_ERROR, "Too many frames, seeking is not possible\n");
73  return AVERROR_INVALIDDATA;
74  }
75  if(c->fcount){
76  c->frames = av_malloc(c->fcount * sizeof(MPCFrame));
77  if(!c->frames){
78  av_log(s, AV_LOG_ERROR, "Cannot allocate seektable\n");
79  return AVERROR(ENOMEM);
80  }
81  }else{
82  av_log(s, AV_LOG_WARNING, "Container reports no frames\n");
83  }
84  c->curframe = 0;
85  c->lastframe = -1;
86  c->curbits = 8;
87  c->frames_noted = 0;
88 
89  st = avformat_new_stream(s, NULL);
90  if (!st)
91  return AVERROR(ENOMEM);
94  st->codec->channels = 2;
96  st->codec->bits_per_coded_sample = 16;
97 
98  if (ff_alloc_extradata(st->codec, 16))
99  return AVERROR(ENOMEM);
100  avio_read(s->pb, st->codec->extradata, 16);
101  st->codec->sample_rate = mpc_rate[st->codec->extradata[2] & 3];
103  /* scan for seekpoints */
104  st->start_time = 0;
105  st->duration = c->fcount;
106 
107  /* try to read APE tags */
108  if (s->pb->seekable) {
109  int64_t pos = avio_tell(s->pb);
110  ff_ape_parse_tag(s);
111  if (!av_dict_get(s->metadata, "", NULL, AV_DICT_IGNORE_SUFFIX))
112  ff_id3v1_read(s);
113  avio_seek(s->pb, pos, SEEK_SET);
114  }
115 
116  return 0;
117 }
118 
120 {
121  MPCContext *c = s->priv_data;
122  int ret, size, size2, curbits, cur = c->curframe;
123  unsigned tmp;
124  int64_t pos;
125 
126  if (c->curframe >= c->fcount && c->fcount)
127  return AVERROR_EOF;
128 
129  if(c->curframe != c->lastframe + 1){
130  avio_seek(s->pb, c->frames[c->curframe].pos, SEEK_SET);
131  c->curbits = c->frames[c->curframe].skip;
132  }
133  c->lastframe = c->curframe;
134  c->curframe++;
135  curbits = c->curbits;
136  pos = avio_tell(s->pb);
137  tmp = avio_rl32(s->pb);
138  if(curbits <= 12){
139  size2 = (tmp >> (12 - curbits)) & 0xFFFFF;
140  }else{
141  size2 = (tmp << (curbits - 12) | avio_rl32(s->pb) >> (44 - curbits)) & 0xFFFFF;
142  }
143  curbits += 20;
144  avio_seek(s->pb, pos, SEEK_SET);
145 
146  size = ((size2 + curbits + 31) & ~31) >> 3;
147  if(cur == c->frames_noted && c->fcount){
148  c->frames[cur].pos = pos;
149  c->frames[cur].size = size;
150  c->frames[cur].skip = curbits - 20;
151  av_add_index_entry(s->streams[0], cur, cur, size, 0, AVINDEX_KEYFRAME);
152  c->frames_noted++;
153  }
154  c->curbits = (curbits + size2) & 0x1F;
155 
156  if ((ret = av_new_packet(pkt, size)) < 0)
157  return ret;
158 
159  pkt->data[0] = curbits;
160  pkt->data[1] = (c->curframe > c->fcount) && c->fcount;
161  pkt->data[2] = 0;
162  pkt->data[3] = 0;
163 
164  pkt->stream_index = 0;
165  pkt->pts = cur;
166  ret = avio_read(s->pb, pkt->data + 4, size);
167  if(c->curbits)
168  avio_seek(s->pb, -4, SEEK_CUR);
169  if(ret < size){
170  av_free_packet(pkt);
171  return ret < 0 ? ret : AVERROR(EIO);
172  }
173  pkt->size = ret + 4;
174 
175  return 0;
176 }
177 
179 {
180  MPCContext *c = s->priv_data;
181 
182  av_freep(&c->frames);
183  return 0;
184 }
185 
186 /**
187  * Seek to the given position
188  * If position is unknown but is within the limits of file
189  * then packets are skipped unless desired position is reached
190  *
191  * Also this function makes use of the fact that timestamp == frameno
192  */
193 static int mpc_read_seek(AVFormatContext *s, int stream_index, int64_t timestamp, int flags)
194 {
195  AVStream *st = s->streams[stream_index];
196  MPCContext *c = s->priv_data;
197  AVPacket pkt1, *pkt = &pkt1;
198  int ret;
199  int index = av_index_search_timestamp(st, FFMAX(timestamp - DELAY_FRAMES, 0), flags);
200  uint32_t lastframe;
201 
202  /* if found, seek there */
203  if (index >= 0 && st->index_entries[st->nb_index_entries-1].timestamp >= timestamp - DELAY_FRAMES){
204  c->curframe = st->index_entries[index].pos;
205  return 0;
206  }
207  /* if timestamp is out of bounds, return error */
208  if(timestamp < 0 || timestamp >= c->fcount)
209  return -1;
210  timestamp -= DELAY_FRAMES;
211  /* seek to the furthest known position and read packets until
212  we reach desired position */
213  lastframe = c->curframe;
214  if(c->frames_noted) c->curframe = c->frames_noted - 1;
215  while(c->curframe < timestamp){
216  ret = av_read_frame(s, pkt);
217  if (ret < 0){
218  c->curframe = lastframe;
219  return ret;
220  }
221  av_free_packet(pkt);
222  }
223  return 0;
224 }
225 
226 
228  .name = "mpc",
229  .long_name = NULL_IF_CONFIG_SMALL("Musepack"),
230  .priv_data_size = sizeof(MPCContext),
236  .extensions = "mpc",
237 };