FFmpeg
mpc.c
Go to the documentation of this file.
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 
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 MPCFrame {
35  int64_t pos;
36  int size, skip;
37 }MPCFrame;
38 
39 typedef struct MPCContext {
40  int ver;
41  uint32_t curframe, lastframe;
42  uint32_t fcount;
44  int curbits;
46 } MPCContext;
47 
48 static int mpc_probe(const 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  goto mem_error;
94  st->codecpar->channels = 2;
97 
98  if (ff_get_extradata(s, st->codecpar, s->pb, 16) < 0)
99  goto mem_error;
100  st->codecpar->sample_rate = mpc_rate[st->codecpar->extradata[2] & 3];
102  /* scan for seekpoints */
103  st->start_time = 0;
104  st->duration = c->fcount;
105 
106  /* try to read APE tags */
107  if (s->pb->seekable & AVIO_SEEKABLE_NORMAL) {
108  int64_t pos = avio_tell(s->pb);
109  ff_ape_parse_tag(s);
111  ff_id3v1_read(s);
112  avio_seek(s->pb, pos, SEEK_SET);
113  }
114 
115  return 0;
116 mem_error:
117  av_freep(&c->frames);
118  return AVERROR(ENOMEM);
119 }
120 
122 {
123  MPCContext *c = s->priv_data;
124  int ret, size, size2, curbits, cur = c->curframe;
125  unsigned tmp;
126  int64_t pos;
127 
128  if (c->curframe >= c->fcount && c->fcount)
129  return AVERROR_EOF;
130 
131  if(c->curframe != c->lastframe + 1){
132  avio_seek(s->pb, c->frames[c->curframe].pos, SEEK_SET);
133  c->curbits = c->frames[c->curframe].skip;
134  }
135  c->lastframe = c->curframe;
136  c->curframe++;
137  curbits = c->curbits;
138  pos = avio_tell(s->pb);
139  tmp = avio_rl32(s->pb);
140  if(curbits <= 12){
141  size2 = (tmp >> (12 - curbits)) & 0xFFFFF;
142  }else{
143  size2 = (tmp << (curbits - 12) | avio_rl32(s->pb) >> (44 - curbits)) & 0xFFFFF;
144  }
145  curbits += 20;
146  avio_seek(s->pb, pos, SEEK_SET);
147 
148  size = ((size2 + curbits + 31) & ~31) >> 3;
149  if(cur == c->frames_noted && c->fcount){
150  c->frames[cur].pos = pos;
151  c->frames[cur].size = size;
152  c->frames[cur].skip = curbits - 20;
153  av_add_index_entry(s->streams[0], cur, cur, size, 0, AVINDEX_KEYFRAME);
154  c->frames_noted++;
155  }
156  c->curbits = (curbits + size2) & 0x1F;
157 
158  if ((ret = av_new_packet(pkt, size + 4)) < 0)
159  return ret;
160 
161  pkt->data[0] = curbits;
162  pkt->data[1] = (c->curframe > c->fcount) && c->fcount;
163  pkt->data[2] = 0;
164  pkt->data[3] = 0;
165 
166  pkt->stream_index = 0;
167  pkt->pts = cur;
168  ret = avio_read(s->pb, pkt->data + 4, size);
169  if(c->curbits)
170  avio_seek(s->pb, -4, SEEK_CUR);
171  if(ret < size){
172  av_packet_unref(pkt);
173  return ret < 0 ? ret : AVERROR(EIO);
174  }
175  pkt->size = ret + 4;
176 
177  return 0;
178 }
179 
181 {
182  MPCContext *c = s->priv_data;
183 
184  av_freep(&c->frames);
185  return 0;
186 }
187 
188 /**
189  * Seek to the given position
190  * If position is unknown but is within the limits of file
191  * then packets are skipped unless desired position is reached
192  *
193  * Also this function makes use of the fact that timestamp == frameno
194  */
195 static int mpc_read_seek(AVFormatContext *s, int stream_index, int64_t timestamp, int flags)
196 {
197  AVStream *st = s->streams[stream_index];
198  MPCContext *c = s->priv_data;
199  AVPacket pkt1, *pkt = &pkt1;
200  int ret;
201  int index = av_index_search_timestamp(st, FFMAX(timestamp - DELAY_FRAMES, 0), flags);
202  uint32_t lastframe;
203 
204  /* if found, seek there */
205  if (index >= 0 && st->index_entries[st->nb_index_entries-1].timestamp >= timestamp - DELAY_FRAMES){
206  c->curframe = st->index_entries[index].pos;
207  return 0;
208  }
209  /* if timestamp is out of bounds, return error */
210  if(timestamp < 0 || timestamp >= c->fcount)
211  return -1;
212  timestamp -= DELAY_FRAMES;
213  /* seek to the furthest known position and read packets until
214  we reach desired position */
215  lastframe = c->curframe;
216  if(c->frames_noted) c->curframe = c->frames_noted - 1;
217  while(c->curframe < timestamp){
218  ret = av_read_frame(s, pkt);
219  if (ret < 0){
220  c->curframe = lastframe;
221  return ret;
222  }
223  av_packet_unref(pkt);
224  }
225  return 0;
226 }
227 
228 
230  .name = "mpc",
231  .long_name = NULL_IF_CONFIG_SMALL("Musepack"),
232  .priv_data_size = sizeof(MPCContext),
238  .extensions = "mpc",
239 };
#define NULL
Definition: coverity.c:32
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:59
int av_add_index_entry(AVStream *st, int64_t pos, int64_t timestamp, int size, int distance, int flags)
Add an index entry into a sorted list.
Definition: utils.c:2049
#define AV_LOG_WARNING
Something somehow does not look correct.
Definition: log.h:182
void avpriv_set_pts_info(AVStream *s, int pts_wrap_bits, unsigned int pts_num, unsigned int pts_den)
Set the time base and wrapping info for a given stream.
Definition: utils.c:4929
int64_t pos
Definition: avformat.h:810
uint32_t fcount
Definition: mpc.c:42
static int read_seek(AVFormatContext *ctx, int stream_index, int64_t timestamp, int flags)
Definition: libcdio.c:153
enum AVCodecID codec_id
Specific type of the encoded data (the codec used).
Definition: avcodec.h:3968
void ff_id3v1_read(AVFormatContext *s)
Read an ID3v1 tag.
Definition: id3v1.c:235
int size
Definition: avcodec.h:1481
int64_t avio_seek(AVIOContext *s, int64_t offset, int whence)
fseek() equivalent for AVIOContext.
Definition: aviobuf.c:246
AVIndexEntry * index_entries
Only used if the format does not support seeking natively.
Definition: avformat.h:1110
static AVPacket pkt
#define AV_CH_LAYOUT_STEREO
Format I/O context.
Definition: avformat.h:1358
Public dictionary API.
static int mpc_read_packet(AVFormatContext *s, AVPacket *pkt)
Definition: mpc.c:121
uint8_t
#define av_malloc(s)
static int mpc_read_seek(AVFormatContext *s, int stream_index, int64_t timestamp, int flags)
Seek to the given position If position is unknown but is within the limits of file then packets are s...
Definition: mpc.c:195
Undefined Behavior In the C some operations are like signed integer dereferencing freed accessing outside allocated Undefined Behavior must not occur in a C it is not safe even if the output of undefined operations is unused The unsafety may seem nit picking but Optimizing compilers have in fact optimized code on the assumption that no undefined Behavior occurs Optimizing code based on wrong assumptions can and has in some cases lead to effects beyond the output of computations The signed integer overflow problem in speed critical code Code which is highly optimized and works with signed integers sometimes has the problem that often the output of the computation does not c
Definition: undefined.txt:32
static int mpc_read_close(AVFormatContext *s)
Definition: mpc.c:180
AVStream * avformat_new_stream(AVFormatContext *s, const AVCodec *c)
Add a new stream to a media file.
Definition: utils.c:4502
AVStream ** streams
A list of all streams in the file.
Definition: avformat.h:1426
AVDictionaryEntry * av_dict_get(const AVDictionary *m, const char *key, const AVDictionaryEntry *prev, int flags)
Get a dictionary entry with matching key.
Definition: dict.c:40
uint8_t * data
Definition: avcodec.h:1480
#define AVERROR_EOF
End of file.
Definition: error.h:55
static av_cold int read_close(AVFormatContext *ctx)
Definition: libcdio.c:145
static av_always_inline int64_t avio_tell(AVIOContext *s)
ftell() equivalent for AVIOContext.
Definition: avio.h:557
uint32_t lastframe
Definition: mpc.c:41
static const int mpc_rate[4]
Definition: mpc.c:33
MPCFrame * frames
Definition: mpc.c:43
uint64_t channel_layout
Audio only.
Definition: avcodec.h:4070
#define av_log(a,...)
int avio_read(AVIOContext *s, unsigned char *buf, int size)
Read size bytes from AVIOContext into buf.
Definition: aviobuf.c:650
int av_new_packet(AVPacket *pkt, int size)
Allocate the payload of a packet and initialize its fields with default values.
Definition: avpacket.c:86
#define AVINDEX_KEYFRAME
Definition: avformat.h:817
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:176
AVDictionary * metadata
Metadata that applies to the whole file.
Definition: avformat.h:1598
int frames_noted
Definition: mpc.c:45
int av_index_search_timestamp(AVStream *st, int64_t timestamp, int flags)
Get the index for a specific timestamp.
Definition: utils.c:2164
int size
Definition: mpc.c:36
unsigned int avio_rl32(AVIOContext *s)
Definition: aviobuf.c:772
int64_t timestamp
Timestamp in AVStream.time_base units, preferably the time from which on correctly decoded frames are...
Definition: avformat.h:811
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:186
enum AVMediaType codec_type
General type of the encoded data.
Definition: avcodec.h:3964
#define DELAY_FRAMES
Definition: mpc.c:31
#define FFMAX(a, b)
Definition: common.h:94
int64_t ff_ape_parse_tag(AVFormatContext *s)
Read and parse an APE tag.
Definition: apetag.c:118
int avio_r8(AVIOContext *s)
Definition: aviobuf.c:641
unsigned char * buf
Buffer must have AVPROBE_PADDING_SIZE of extra allocated bytes filled with zero.
Definition: avformat.h:448
int seekable
A combination of AVIO_SEEKABLE_ flags or 0 when the stream is not seekable.
Definition: avio.h:260
audio channel layout utility functions
uint32_t curframe
Definition: mpc.c:41
#define s(width, name)
Definition: cbs_vp9.c:257
int skip
Definition: mpc.c:36
AVInputFormat ff_mpc_demuxer
Definition: mpc.c:229
#define MPC_FRAMESIZE
Definition: mpc.c:30
static int read_header(FFV1Context *f)
Definition: ffv1dec.c:530
Stream structure.
Definition: avformat.h:881
static int read_packet(void *opaque, uint8_t *buf, int buf_size)
Definition: avio_reading.c:42
#define AVIO_SEEKABLE_NORMAL
Seeking works like for a local file.
Definition: avio.h:40
int64_t pos
Definition: mpc.c:35
AVIOContext * pb
I/O context.
Definition: avformat.h:1400
void av_packet_unref(AVPacket *pkt)
Wipe the packet.
Definition: avpacket.c:599
int nb_index_entries
Definition: avformat.h:1112
int index
Definition: gxfenc.c:89
Definition: mpc.c:34
This structure contains the data a format has to probe a file.
Definition: avformat.h:446
int av_read_frame(AVFormatContext *s, AVPacket *pkt)
Return the next frame of a stream.
Definition: utils.c:1777
#define flags(name, subs,...)
Definition: cbs_av1.c:561
static int read_probe(const AVProbeData *pd)
Definition: jvdec.c:55
int64_t duration
Decoding: duration of the stream, in stream time base.
Definition: avformat.h:930
int sample_rate
Audio only.
Definition: avcodec.h:4078
#define AVPROBE_SCORE_MAX
maximum score
Definition: avformat.h:458
Main libavformat public API header.
static int mpc_read_header(AVFormatContext *s)
Definition: mpc.c:56
int curbits
Definition: mpc.c:44
int64_t start_time
Decoding: pts of the first frame of the stream in presentation order, in stream time base...
Definition: avformat.h:920
int ff_get_extradata(AVFormatContext *s, AVCodecParameters *par, AVIOContext *pb, int size)
Allocate extradata with additional AV_INPUT_BUFFER_PADDING_SIZE at end which is always set to 0 and f...
Definition: utils.c:3339
int frames
Definition: mpc.h:62
void * priv_data
Format private data.
Definition: avformat.h:1386
int bits_per_coded_sample
The number of bits per sample in the codedwords.
Definition: avcodec.h:4010
uint8_t * extradata
Extra binary data needed for initializing the decoder, codec-dependent.
Definition: avcodec.h:3982
int channels
Audio only.
Definition: avcodec.h:4074
#define av_freep(p)
const char * name
A comma separated list of short names for the format.
Definition: avformat.h:654
#define AV_DICT_IGNORE_SUFFIX
Return first entry in a dictionary whose first part corresponds to the search key, ignoring the suffix of the found key string.
Definition: dict.h:70
AVCodecParameters * codecpar
Codec parameters associated with this stream.
Definition: avformat.h:1028
unsigned int avio_rl24(AVIOContext *s)
Definition: aviobuf.c:764
int stream_index
Definition: avcodec.h:1482
Filter the word “frame” indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a all references to both lists are replaced with a reference to the intersection And when a single format is eventually chosen for a link amongst the remaining all references to the list are updated That means that if a filter requires that its input and output have the same format amongst a supported all it has to do is use a reference to the same list of formats query_formats can leave some formats unset and return AVERROR(EAGAIN) to cause the negotiation mechanism toagain later.That can be used by filters with complex requirements to use the format negotiated on one link to set the formats supported on another.Frame references ownership and permissions
#define MKTAG(a, b, c, d)
Definition: common.h:366
static int mpc_probe(const AVProbeData *p)
Definition: mpc.c:48
This structure stores compressed data.
Definition: avcodec.h:1457
int64_t pts
Presentation timestamp in AVStream->time_base units; the time at which the decompressed packet will b...
Definition: avcodec.h:1473
Definition: mpc.h:52
int ver
Definition: mpc.c:40
static uint8_t tmp[11]
Definition: aes_ctr.c:26