FFmpeg: libavformat/mxg.c Source File

FFmpeg
mxg.c
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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 
22 #include "libavutil/channel_layout.h"
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 {
34   uint8_t *buffer;
35   uint8_t *buffer_ptr;
36   uint8_t *soi_ptr;
37   unsigned int buffer_size;
38   int64_t dts;
39   unsigned int cache_size;
40 } MXGContext;
41 
42  static int mxg_read_header(AVFormatContext *s)
43 {
44  AVStream *video_st, *audio_st;
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);
51  video_st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
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);
58  audio_st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
59  audio_st->codecpar->codec_id = AV_CODEC_ID_PCM_ALAW;
60  audio_st->codecpar->ch_layout = (AVChannelLayout)AV_CHANNEL_LAYOUT_MONO;
61  audio_st->codecpar->sample_rate = 8000;
62  audio_st->codecpar->bits_per_coded_sample = 8;
63  audio_st->codecpar->block_align = 1;
64  avpriv_set_pts_info(audio_st, 64, 1, 1000000);
65 
66  mxg->soi_ptr = mxg->buffer_ptr = mxg->buffer = 0;
67  mxg->buffer_size = 0;
68  mxg->dts = AV_NOPTS_VALUE;
69  mxg->cache_size = 0;
70 
71  return 0;
72 }
73 
74  static uint8_t* mxg_find_startmarker(uint8_t *p, uint8_t *end)
75 {
76  for (; p < end - 3; p += 4) {
77  uint32_t x = AV_RN32(p);
78 
79  if (x & (~(x+0x01010101)) & 0x80808080) {
80  if (p[0] == 0xff) {
81  return p;
82  } else if (p[1] == 0xff) {
83  return p+1;
84  } else if (p[2] == 0xff) {
85  return p+2;
86  } else if (p[3] == 0xff) {
87  return p+3;
88  }
89  }
90  }
91 
92  for (; p < end; ++p) {
93  if (*p == 0xff) return p;
94  }
95 
96  return end;
97 }
98 
99  static int mxg_update_cache(AVFormatContext *s, unsigned int cache_size)
100 {
101  MXGContext *mxg = s->priv_data;
102  unsigned int current_pos = mxg->buffer_ptr - mxg->buffer;
103  unsigned int soi_pos;
104  uint8_t *buffer;
105  int ret;
106 
107  /* reallocate internal buffer */
108  if (current_pos > current_pos + cache_size)
109  return AVERROR(ENOMEM);
110  soi_pos = mxg->soi_ptr - mxg->buffer;
111  buffer = av_fast_realloc(mxg->buffer, &mxg->buffer_size,
112  current_pos + cache_size +
113  AV_INPUT_BUFFER_PADDING_SIZE);
114  if (!buffer)
115  return AVERROR(ENOMEM);
116  mxg->buffer = buffer;
117  mxg->buffer_ptr = mxg->buffer + current_pos;
118  if (mxg->soi_ptr) mxg->soi_ptr = mxg->buffer + soi_pos;
119 
120  /* get data */
121  ret = avio_read(s->pb, mxg->buffer_ptr + mxg->cache_size,
122  cache_size - mxg->cache_size);
123  if (ret < 0)
124  return ret;
125 
126  mxg->cache_size += ret;
127 
128  return ret;
129 }
130 
131  static int mxg_read_packet(AVFormatContext *s, AVPacket *pkt)
132 {
133  int ret;
134  unsigned int size;
135  uint8_t *startmarker_ptr, *end, *search_end, marker;
136  MXGContext *mxg = s->priv_data;
137 
138  while (!avio_feof(s->pb) && !s->pb->error){
139  if (mxg->cache_size <= OVERREAD_SIZE) {
140  /* update internal buffer */
141  ret = mxg_update_cache(s, DEFAULT_PACKET_SIZE + OVERREAD_SIZE);
142  if (ret < 0)
143  return ret;
144  }
145  end = mxg->buffer_ptr + mxg->cache_size;
146 
147  /* find start marker - 0xff */
148  if (mxg->cache_size > OVERREAD_SIZE) {
149  search_end = end - OVERREAD_SIZE;
150  startmarker_ptr = mxg_find_startmarker(mxg->buffer_ptr, search_end);
151  } else {
152  search_end = end;
153  startmarker_ptr = mxg_find_startmarker(mxg->buffer_ptr, search_end);
154  if (startmarker_ptr >= search_end - 1 ||
155  *(startmarker_ptr + 1) != EOI) break;
156  }
157 
158  if (startmarker_ptr != search_end) { /* start marker found */
159  marker = *(startmarker_ptr + 1);
160  mxg->buffer_ptr = startmarker_ptr + 2;
161  mxg->cache_size = end - mxg->buffer_ptr;
162 
163  if (marker == SOI) {
164  mxg->soi_ptr = startmarker_ptr;
165  } else if (marker == EOI) {
166  if (!mxg->soi_ptr) {
167  av_log(s, AV_LOG_WARNING, "Found EOI before SOI, skipping\n");
168  continue;
169  }
170 
171  size = mxg->buffer_ptr - mxg->soi_ptr;
172  ret = av_new_packet(pkt, size);
173  if (ret < 0)
174  return ret;
175  memcpy(pkt->data, mxg->soi_ptr, size);
176 
177  pkt->pts = pkt->dts = mxg->dts;
178  pkt->stream_index = 0;
179 
180  if (mxg->soi_ptr - mxg->buffer > mxg->cache_size) {
181  if (mxg->cache_size > 0) {
182  memmove(mxg->buffer, mxg->buffer_ptr, mxg->cache_size);
183  }
184 
185  mxg->buffer_ptr = mxg->buffer;
186  }
187  mxg->soi_ptr = 0;
188 
189  return pkt->size;
190  } else if ( (SOF0 <= marker && marker <= SOF15) ||
191  (SOS <= marker && marker <= COM) ) {
192  /* all other markers that start marker segment also contain
193  length value (see specification for JPEG Annex B.1) */
194  size = AV_RB16(mxg->buffer_ptr);
195  if (size < 2)
196  return AVERROR(EINVAL);
197 
198  if (mxg->cache_size < size) {
199  ret = mxg_update_cache(s, size);
200  if (ret < 0)
201  return ret;
202  startmarker_ptr = mxg->buffer_ptr - 2;
203  mxg->cache_size = 0;
204  } else {
205  mxg->cache_size -= size;
206  }
207 
208  mxg->buffer_ptr += size;
209 
210  if (marker == APP13 && size >= 16) { /* audio data */
211  ret = av_new_packet(pkt, size - 14);
212  if (ret < 0)
213  return ret;
214  memcpy(pkt->data, startmarker_ptr + 16, size - 14);
215 
216  /* time (GMT) of first sample in usec since 1970, little-endian */
217  pkt->pts = pkt->dts = AV_RL64(startmarker_ptr + 8);
218  pkt->stream_index = 1;
219 
220  if (startmarker_ptr - mxg->buffer > mxg->cache_size) {
221  if (mxg->cache_size > 0) {
222  memcpy(mxg->buffer, mxg->buffer_ptr, mxg->cache_size);
223  }
224  mxg->buffer_ptr = mxg->buffer;
225  }
226 
227  return pkt->size;
228  } else if (marker == COM && size >= 18 &&
229  !strncmp(startmarker_ptr + 4, "MXF", 3)) {
230  /* time (GMT) of video frame in usec since 1970, little-endian */
231  mxg->dts = AV_RL64(startmarker_ptr + 12);
232  }
233  }
234  } else {
235  /* start marker not found */
236  mxg->buffer_ptr = search_end;
237  mxg->cache_size = OVERREAD_SIZE;
238  }
239  }
240 
241  return AVERROR_EOF;
242 }
243 
244  static int mxg_close(struct AVFormatContext *s)
245 {
246  MXGContext *mxg = s->priv_data;
247  av_freep(&mxg->buffer);
248  return 0;
249 }
250 
251  const AVInputFormat ff_mxg_demuxer = {
252  .name = "mxg",
253  .long_name = NULL_IF_CONFIG_SMALL("MxPEG clip"),
254  .priv_data_size = sizeof(MXGContext),
255  .read_header = mxg_read_header,
256  .read_packet = mxg_read_packet,
257  .read_close = mxg_close,
258  .extensions = "mxg",
259 };
AV_LOG_WARNING
#define AV_LOG_WARNING
Something somehow does not look correct.
Definition: log.h:186
mjpeg.h
AVERROR
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
avformat_new_stream
AVStream * avformat_new_stream(AVFormatContext *s, const AVCodec *c)
Add a new stream to a media file.
Definition: options.c:237
AVCodecParameters::codec_type
enum AVMediaType codec_type
General type of the encoded data.
Definition: codec_par.h:57
MXGContext::buffer_size
unsigned int buffer_size
Definition: mxg.c:37
SOS
@ SOS
Definition: mjpeg.h:72
AV_RL64
uint64_t_TMPL AV_RL64
Definition: bytestream.h:91
AVERROR_EOF
#define AVERROR_EOF
End of file.
Definition: error.h:57
SOF0
@ SOF0
Definition: mjpeg.h:39
AVPacket::data
uint8_t * data
Definition: packet.h:374
mxg_read_header
static int mxg_read_header(AVFormatContext *s)
Definition: mxg.c:42
AV_CHANNEL_LAYOUT_MONO
#define AV_CHANNEL_LAYOUT_MONO
Definition: channel_layout.h:353
AV_CODEC_ID_MXPEG
@ AV_CODEC_ID_MXPEG
Definition: codec_id.h:196
MXGContext::buffer
uint8_t * buffer
Definition: mxg.c:34
mxg_update_cache
static int mxg_update_cache(AVFormatContext *s, unsigned int cache_size)
Definition: mxg.c:99
avpriv_set_pts_info
void avpriv_set_pts_info(AVStream *st, int pts_wrap_bits, unsigned int pts_num, unsigned int pts_den)
Set the time base and wrapping info for a given stream.
Definition: avformat.c:697
mxg_find_startmarker
static uint8_t * mxg_find_startmarker(uint8_t *p, uint8_t *end)
Definition: mxg.c:74
read_close
static av_cold int read_close(AVFormatContext *ctx)
Definition: libcdio.c:143
APP13
@ APP13
Definition: mjpeg.h:92
pkt
AVPacket * pkt
Definition: movenc.c:59
AVInputFormat
Definition: avformat.h:656
COM
@ COM
Definition: mjpeg.h:111
av_fast_realloc
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:505
intreadwrite.h
s
#define s(width, name)
Definition: cbs_vp9.c:256
av_new_packet
int av_new_packet(AVPacket *pkt, int size)
Allocate the payload of a packet and initialize its fields with default values.
Definition: avpacket.c:97
AVInputFormat::name
const char * name
A comma separated list of short names for the format.
Definition: avformat.h:661
AVMEDIA_TYPE_AUDIO
@ AVMEDIA_TYPE_AUDIO
Definition: avutil.h:202
MXGContext::cache_size
unsigned int cache_size
Definition: mxg.c:39
MXGContext::buffer_ptr
uint8_t * buffer_ptr
Definition: mxg.c:35
OVERREAD_SIZE
#define OVERREAD_SIZE
Definition: mxg.c:31
MXGContext::dts
int64_t dts
Definition: mxg.c:38
AVFormatContext
Format I/O context.
Definition: avformat.h:1213
AV_CODEC_ID_PCM_ALAW
@ AV_CODEC_ID_PCM_ALAW
Definition: codec_id.h:325
internal.h
AVStream::codecpar
AVCodecParameters * codecpar
Codec parameters associated with this stream.
Definition: avformat.h:1108
read_header
static int read_header(FFV1Context *f)
Definition: ffv1dec.c:532
NULL
#define NULL
Definition: coverity.c:32
AV_RN32
#define AV_RN32(p)
Definition: intreadwrite.h:364
AVCodecParameters::ch_layout
AVChannelLayout ch_layout
Audio only.
Definition: codec_par.h:212
audio_st
AVStream * audio_st
Definition: movenc.c:60
AVCodecParameters::sample_rate
int sample_rate
Audio only.
Definition: codec_par.h:177
AVPacket::size
int size
Definition: packet.h:375
NULL_IF_CONFIG_SMALL
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification.
Definition: internal.h:117
AVChannelLayout
An AVChannelLayout holds information about the channel layout of audio data.
Definition: channel_layout.h:290
MXGContext::soi_ptr
uint8_t * soi_ptr
Definition: mxg.c:36
size
int size
Definition: twinvq_data.h:10344
avio.h
video_st
AVStream * video_st
Definition: movenc.c:60
AV_NOPTS_VALUE
#define AV_NOPTS_VALUE
Undefined timestamp value.
Definition: avutil.h:248
SOF15
@ SOF15
Definition: mjpeg.h:54
AVPacket::dts
int64_t dts
Decompression timestamp in AVStream->time_base units; the time at which the packet is decompressed.
Definition: packet.h:373
AVPacket::pts
int64_t pts
Presentation timestamp in AVStream->time_base units; the time at which the decompressed packet will b...
Definition: packet.h:367
EOI
@ EOI
Definition: mjpeg.h:71
internal.h
AVCodecParameters::block_align
int block_align
Audio only.
Definition: codec_par.h:184
mxg_read_packet
static int mxg_read_packet(AVFormatContext *s, AVPacket *pkt)
Definition: mxg.c:131
MXGContext
Definition: mxg.c:33
ret
ret
Definition: filter_design.txt:187
read_packet
static int read_packet(void *opaque, uint8_t *buf, int buf_size)
Definition: avio_reading.c:42
AVStream
Stream structure.
Definition: avformat.h:948
mxg_close
static int mxg_close(struct AVFormatContext *s)
Definition: mxg.c:244
avformat.h
AV_INPUT_BUFFER_PADDING_SIZE
#define AV_INPUT_BUFFER_PADDING_SIZE
Definition: defs.h:40
ff_mxg_demuxer
const AVInputFormat ff_mxg_demuxer
Definition: mxg.c:251
channel_layout.h
buffer
the frame and frame reference mechanism is intended to as much as expensive copies of that data while still allowing the filters to produce correct results The data is stored in buffers represented by AVFrame structures Several references can point to the same frame buffer
Definition: filter_design.txt:49
avio_read
int avio_read(AVIOContext *s, unsigned char *buf, int size)
Read size bytes from AVIOContext into buf.
Definition: aviobuf.c:641
AVPacket::stream_index
int stream_index
Definition: packet.h:376
AVMEDIA_TYPE_VIDEO
@ AVMEDIA_TYPE_VIDEO
Definition: avutil.h:201
AVCodecParameters::bits_per_coded_sample
int bits_per_coded_sample
The number of bits per sample in the codedwords.
Definition: codec_par.h:103
SOI
@ SOI
Definition: mjpeg.h:70
DEFAULT_PACKET_SIZE
#define DEFAULT_PACKET_SIZE
Definition: mxg.c:30
AVCodecParameters::codec_id
enum AVCodecID codec_id
Specific type of the encoded data (the codec used).
Definition: codec_par.h:61
AVPacket
This structure stores compressed data.
Definition: packet.h:351
av_freep
#define av_freep(p)
Definition: tableprint_vlc.h:34
av_log
#define av_log(a,...)
Definition: tableprint_vlc.h:27
AV_RB16
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:98
avio_feof
int avio_feof(AVIOContext *s)
Similar to feof() but also returns nonzero on read errors.
Definition: aviobuf.c:375
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