FFmpeg
mxg.c
Go to the documentation of this file.
1 /*
2  * MxPEG clip file demuxer
3  * Copyright (c) 2010 Anatoly Nenashev
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 "libavutil/internal.h"
24 #include "libavutil/intreadwrite.h"
25 #include "libavcodec/mjpeg.h"
26 #include "avformat.h"
27 #include "internal.h"
28 #include "avio.h"
29 
30 #define DEFAULT_PACKET_SIZE 1024
31 #define OVERREAD_SIZE 3
32 
33 typedef struct MXGContext {
37  unsigned int buffer_size;
38  int64_t dts;
39  unsigned int cache_size;
40 } MXGContext;
41 
43 {
45  MXGContext *mxg = s->priv_data;
46 
47  /* video parameters will be extracted from the compressed bitstream */
48  video_st = avformat_new_stream(s, NULL);
49  if (!video_st)
50  return AVERROR(ENOMEM);
52  video_st->codecpar->codec_id = AV_CODEC_ID_MXPEG;
53  avpriv_set_pts_info(video_st, 64, 1, 1000000);
54 
55  audio_st = avformat_new_stream(s, NULL);
56  if (!audio_st)
57  return AVERROR(ENOMEM);
60  audio_st->codecpar->channels = 1;
62  audio_st->codecpar->sample_rate = 8000;
63  audio_st->codecpar->bits_per_coded_sample = 8;
64  audio_st->codecpar->block_align = 1;
65  avpriv_set_pts_info(audio_st, 64, 1, 1000000);
66 
67  mxg->soi_ptr = mxg->buffer_ptr = mxg->buffer = 0;
68  mxg->buffer_size = 0;
69  mxg->dts = AV_NOPTS_VALUE;
70  mxg->cache_size = 0;
71 
72  return 0;
73 }
74 
76 {
77  for (; p < end - 3; p += 4) {
78  uint32_t x = AV_RN32(p);
79 
80  if (x & (~(x+0x01010101)) & 0x80808080) {
81  if (p[0] == 0xff) {
82  return p;
83  } else if (p[1] == 0xff) {
84  return p+1;
85  } else if (p[2] == 0xff) {
86  return p+2;
87  } else if (p[3] == 0xff) {
88  return p+3;
89  }
90  }
91  }
92 
93  for (; p < end; ++p) {
94  if (*p == 0xff) return p;
95  }
96 
97  return end;
98 }
99 
100 static int mxg_update_cache(AVFormatContext *s, unsigned int cache_size)
101 {
102  MXGContext *mxg = s->priv_data;
103  unsigned int current_pos = mxg->buffer_ptr - mxg->buffer;
104  unsigned int soi_pos;
105  uint8_t *buffer;
106  int ret;
107 
108  /* reallocate internal buffer */
109  if (current_pos > current_pos + cache_size)
110  return AVERROR(ENOMEM);
111  soi_pos = mxg->soi_ptr - mxg->buffer;
112  buffer = av_fast_realloc(mxg->buffer, &mxg->buffer_size,
113  current_pos + cache_size +
115  if (!buffer)
116  return AVERROR(ENOMEM);
117  mxg->buffer = buffer;
118  mxg->buffer_ptr = mxg->buffer + current_pos;
119  if (mxg->soi_ptr) mxg->soi_ptr = mxg->buffer + soi_pos;
120 
121  /* get data */
122  ret = avio_read(s->pb, mxg->buffer_ptr + mxg->cache_size,
123  cache_size - mxg->cache_size);
124  if (ret < 0)
125  return ret;
126 
127  mxg->cache_size += ret;
128 
129  return ret;
130 }
131 
133 {
134  int ret;
135  unsigned int size;
136  uint8_t *startmarker_ptr, *end, *search_end, marker;
137  MXGContext *mxg = s->priv_data;
138 
139  while (!avio_feof(s->pb) && !s->pb->error){
140  if (mxg->cache_size <= OVERREAD_SIZE) {
141  /* update internal buffer */
143  if (ret < 0)
144  return ret;
145  }
146  end = mxg->buffer_ptr + mxg->cache_size;
147 
148  /* find start marker - 0xff */
149  if (mxg->cache_size > OVERREAD_SIZE) {
150  search_end = end - OVERREAD_SIZE;
151  startmarker_ptr = mxg_find_startmarker(mxg->buffer_ptr, search_end);
152  } else {
153  search_end = end;
154  startmarker_ptr = mxg_find_startmarker(mxg->buffer_ptr, search_end);
155  if (startmarker_ptr >= search_end - 1 ||
156  *(startmarker_ptr + 1) != EOI) break;
157  }
158 
159  if (startmarker_ptr != search_end) { /* start marker found */
160  marker = *(startmarker_ptr + 1);
161  mxg->buffer_ptr = startmarker_ptr + 2;
162  mxg->cache_size = end - mxg->buffer_ptr;
163 
164  if (marker == SOI) {
165  mxg->soi_ptr = startmarker_ptr;
166  } else if (marker == EOI) {
167  if (!mxg->soi_ptr) {
168  av_log(s, AV_LOG_WARNING, "Found EOI before SOI, skipping\n");
169  continue;
170  }
171 
172  size = mxg->buffer_ptr - mxg->soi_ptr;
173  ret = av_new_packet(pkt, size);
174  if (ret < 0)
175  return ret;
176  memcpy(pkt->data, mxg->soi_ptr, size);
177 
178  pkt->pts = pkt->dts = mxg->dts;
179  pkt->stream_index = 0;
180 
181  if (mxg->soi_ptr - mxg->buffer > mxg->cache_size) {
182  if (mxg->cache_size > 0) {
183  memmove(mxg->buffer, mxg->buffer_ptr, mxg->cache_size);
184  }
185 
186  mxg->buffer_ptr = mxg->buffer;
187  }
188  mxg->soi_ptr = 0;
189 
190  return pkt->size;
191  } else if ( (SOF0 <= marker && marker <= SOF15) ||
192  (SOS <= marker && marker <= COM) ) {
193  /* all other markers that start marker segment also contain
194  length value (see specification for JPEG Annex B.1) */
195  size = AV_RB16(mxg->buffer_ptr);
196  if (size < 2)
197  return AVERROR(EINVAL);
198 
199  if (mxg->cache_size < size) {
200  ret = mxg_update_cache(s, size);
201  if (ret < 0)
202  return ret;
203  startmarker_ptr = mxg->buffer_ptr - 2;
204  mxg->cache_size = 0;
205  } else {
206  mxg->cache_size -= size;
207  }
208 
209  mxg->buffer_ptr += size;
210 
211  if (marker == APP13 && size >= 16) { /* audio data */
212  ret = av_new_packet(pkt, size - 14);
213  if (ret < 0)
214  return ret;
215  memcpy(pkt->data, startmarker_ptr + 16, size - 14);
216 
217  /* time (GMT) of first sample in usec since 1970, little-endian */
218  pkt->pts = pkt->dts = AV_RL64(startmarker_ptr + 8);
219  pkt->stream_index = 1;
220 
221  if (startmarker_ptr - mxg->buffer > mxg->cache_size) {
222  if (mxg->cache_size > 0) {
223  memcpy(mxg->buffer, mxg->buffer_ptr, mxg->cache_size);
224  }
225  mxg->buffer_ptr = mxg->buffer;
226  }
227 
228  return pkt->size;
229  } else if (marker == COM && size >= 18 &&
230  !strncmp(startmarker_ptr + 4, "MXF", 3)) {
231  /* time (GMT) of video frame in usec since 1970, little-endian */
232  mxg->dts = AV_RL64(startmarker_ptr + 12);
233  }
234  }
235  } else {
236  /* start marker not found */
237  mxg->buffer_ptr = search_end;
238  mxg->cache_size = OVERREAD_SIZE;
239  }
240  }
241 
242  return AVERROR_EOF;
243 }
244 
245 static int mxg_close(struct AVFormatContext *s)
246 {
247  MXGContext *mxg = s->priv_data;
248  av_freep(&mxg->buffer);
249  return 0;
250 }
251 
253  .name = "mxg",
254  .long_name = NULL_IF_CONFIG_SMALL("MxPEG clip"),
255  .priv_data_size = sizeof(MXGContext),
259  .extensions = "mxg",
260 };
#define NULL
Definition: coverity.c:32
Buffered I/O operations.
Definition: mjpeg.h:71
Definition: mjpeg.h:111
#define AV_LOG_WARNING
Something somehow does not look correct.
Definition: log.h:182
static uint8_t * mxg_find_startmarker(uint8_t *p, uint8_t *end)
Definition: mxg.c:75
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:4892
enum AVCodecID codec_id
Specific type of the encoded data (the codec used).
Definition: avcodec.h:3957
int size
Definition: avcodec.h:1478
uint64_t_TMPL AV_RL64
Definition: bytestream.h:87
static AVPacket pkt
uint64_t_TMPL AV_WL64 unsigned int_TMPL AV_WL32 unsigned int_TMPL AV_WL24 unsigned int_TMPL AV_WL16 uint64_t_TMPL AV_WB64 unsigned int_TMPL AV_WB32 unsigned int_TMPL AV_WB24 unsigned int_TMPL AV_RB16
Definition: bytestream.h:87
MJPEG encoder and decoder.
Format I/O context.
Definition: avformat.h:1358
Definition: mjpeg.h:72
uint8_t
static av_cold int end(AVCodecContext *avctx)
Definition: avrndec.c:90
AVStream * avformat_new_stream(AVFormatContext *s, const AVCodec *c)
Add a new stream to a media file.
Definition: utils.c:4465
Definition: mjpeg.h:54
uint8_t * data
Definition: avcodec.h:1477
#define AVERROR_EOF
End of file.
Definition: error.h:55
static av_cold int read_close(AVFormatContext *ctx)
Definition: libcdio.c:145
unsigned int cache_size
Definition: mxg.c:39
ptrdiff_t size
Definition: opengl_enc.c:100
uint64_t channel_layout
Audio only.
Definition: avcodec.h:4059
#define av_log(a,...)
uint8_t * buffer
Definition: mxg.c:34
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 NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:186
AVStream * video_st
Definition: movenc.c:59
enum AVMediaType codec_type
General type of the encoded data.
Definition: avcodec.h:3953
uint8_t * soi_ptr
Definition: mxg.c:36
Definition: mjpeg.h:39
Definition: mjpeg.h:70
static int mxg_read_packet(AVFormatContext *s, AVPacket *pkt)
Definition: mxg.c:132
common internal API header
int block_align
Audio only.
Definition: avcodec.h:4074
audio channel layout utility functions
int64_t dts
Definition: mxg.c:38
#define s(width, name)
Definition: cbs_vp9.c:257
uint8_t * buffer_ptr
Definition: mxg.c:35
#define DEFAULT_PACKET_SIZE
Definition: mxg.c:30
AVInputFormat ff_mxg_demuxer
Definition: mxg.c:252
void * av_fast_realloc(void *ptr, unsigned int *size, size_t min_size)
Reallocate the given buffer if it is not large enough, otherwise do nothing.
Definition: mem.c:476
static int mxg_update_cache(AVFormatContext *s, unsigned int cache_size)
Definition: mxg.c:100
Definition: mxg.c:33
#define OVERREAD_SIZE
Definition: mxg.c:31
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
AVIOContext * pb
I/O context.
Definition: avformat.h:1400
AVStream * audio_st
Definition: movenc.c:59
int error
contains the error code or 0 if no error happened
Definition: avio.h:245
#define AV_RN32(p)
Definition: intreadwrite.h:364
int sample_rate
Audio only.
Definition: avcodec.h:4067
Main libavformat public API header.
static int mxg_close(struct AVFormatContext *s)
Definition: mxg.c:245
Definition: mjpeg.h:92
#define AV_INPUT_BUFFER_PADDING_SIZE
Required number of additionally allocated bytes at the end of the input bitstream for decoding...
Definition: avcodec.h:790
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:3999
int channels
Audio only.
Definition: avcodec.h:4063
int64_t dts
Decompression timestamp in AVStream->time_base units; the time at which the packet is decompressed...
Definition: avcodec.h:1476
#define av_freep(p)
const char * name
A comma separated list of short names for the format.
Definition: avformat.h:654
unsigned int buffer_size
Definition: mxg.c:37
AVCodecParameters * codecpar
Codec parameters associated with this stream.
Definition: avformat.h:1028
int avio_feof(AVIOContext *s)
Similar to feof() but also returns nonzero on read errors.
Definition: aviobuf.c:361
int stream_index
Definition: avcodec.h:1479
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 AV_CH_LAYOUT_MONO
This structure stores compressed data.
Definition: avcodec.h:1454
int64_t pts
Presentation timestamp in AVStream->time_base units; the time at which the decompressed packet will b...
Definition: avcodec.h:1470
#define AV_NOPTS_VALUE
Undefined timestamp value.
Definition: avutil.h:248
static int mxg_read_header(AVFormatContext *s)
Definition: mxg.c:42