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 "libavutil/mem.h"
26 #include "libavcodec/mjpeg.h"
27 #include "avformat.h"
28 #include "demux.h"
29 #include "internal.h"
30 #include "avio.h"
31 
32  #define DEFAULT_PACKET_SIZE 1024
33  #define OVERREAD_SIZE 3
34 
35  typedef struct MXGContext {
36   uint8_t *buffer;
37   uint8_t *buffer_ptr;
38   uint8_t *soi_ptr;
39   unsigned int buffer_size;
40   int64_t dts;
41   unsigned int cache_size;
42 } MXGContext;
43 
44  static int mxg_read_header(AVFormatContext *s)
45 {
46  AVStream *video_st, *audio_st;
47  MXGContext *mxg = s->priv_data;
48 
49  /* video parameters will be extracted from the compressed bitstream */
50  video_st = avformat_new_stream(s, NULL);
51  if (!video_st)
52  return AVERROR(ENOMEM);
53  video_st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
54  video_st->codecpar->codec_id = AV_CODEC_ID_MXPEG;
55  avpriv_set_pts_info(video_st, 64, 1, 1000000);
56 
57  audio_st = avformat_new_stream(s, NULL);
58  if (!audio_st)
59  return AVERROR(ENOMEM);
60  audio_st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
61  audio_st->codecpar->codec_id = AV_CODEC_ID_PCM_ALAW;
62  audio_st->codecpar->ch_layout = (AVChannelLayout)AV_CHANNEL_LAYOUT_MONO;
63  audio_st->codecpar->sample_rate = 8000;
64  audio_st->codecpar->bits_per_coded_sample = 8;
65  audio_st->codecpar->block_align = 1;
66  avpriv_set_pts_info(audio_st, 64, 1, 1000000);
67 
68  mxg->soi_ptr = mxg->buffer_ptr = mxg->buffer = 0;
69  mxg->buffer_size = 0;
70  mxg->dts = AV_NOPTS_VALUE;
71  mxg->cache_size = 0;
72 
73  return 0;
74 }
75 
76  static uint8_t* mxg_find_startmarker(uint8_t *p, uint8_t *end)
77 {
78  for (; p < end - 3; p += 4) {
79  uint32_t x = AV_RN32(p);
80 
81  if (x & (~(x+0x01010101)) & 0x80808080) {
82  if (p[0] == 0xff) {
83  return p;
84  } else if (p[1] == 0xff) {
85  return p+1;
86  } else if (p[2] == 0xff) {
87  return p+2;
88  } else if (p[3] == 0xff) {
89  return p+3;
90  }
91  }
92  }
93 
94  for (; p < end; ++p) {
95  if (*p == 0xff) return p;
96  }
97 
98  return end;
99 }
100 
101  static int mxg_update_cache(AVFormatContext *s, unsigned int cache_size)
102 {
103  MXGContext *mxg = s->priv_data;
104  unsigned int current_pos = mxg->buffer_ptr - mxg->buffer;
105  unsigned int soi_pos;
106  uint8_t *buffer;
107  int ret;
108 
109  /* reallocate internal buffer */
110  if (current_pos > current_pos + cache_size)
111  return AVERROR(ENOMEM);
112  soi_pos = mxg->soi_ptr - mxg->buffer;
113  buffer = av_fast_realloc(mxg->buffer, &mxg->buffer_size,
114  current_pos + cache_size +
115  AV_INPUT_BUFFER_PADDING_SIZE);
116  if (!buffer)
117  return AVERROR(ENOMEM);
118  mxg->buffer = buffer;
119  mxg->buffer_ptr = mxg->buffer + current_pos;
120  if (mxg->soi_ptr) mxg->soi_ptr = mxg->buffer + soi_pos;
121 
122  /* get data */
123  ret = avio_read(s->pb, mxg->buffer_ptr + mxg->cache_size,
124  cache_size - mxg->cache_size);
125  if (ret < 0)
126  return ret;
127 
128  mxg->cache_size += ret;
129 
130  memset(mxg->buffer_ptr + mxg->cache_size, 0, AV_INPUT_BUFFER_PADDING_SIZE);
131 
132  return ret;
133 }
134 
135  static int mxg_read_packet(AVFormatContext *s, AVPacket *pkt)
136 {
137  int ret;
138  unsigned int size;
139  uint8_t *startmarker_ptr, *end, *search_end, marker;
140  MXGContext *mxg = s->priv_data;
141 
142  while (!avio_feof(s->pb) && !s->pb->error){
143  if (mxg->cache_size <= OVERREAD_SIZE) {
144  /* update internal buffer */
145  ret = mxg_update_cache(s, DEFAULT_PACKET_SIZE + OVERREAD_SIZE);
146  if (ret < 0)
147  return ret;
148  }
149  end = mxg->buffer_ptr + mxg->cache_size;
150 
151  /* find start marker - 0xff */
152  if (mxg->cache_size > OVERREAD_SIZE) {
153  search_end = end - OVERREAD_SIZE;
154  startmarker_ptr = mxg_find_startmarker(mxg->buffer_ptr, search_end);
155  } else {
156  search_end = end;
157  startmarker_ptr = mxg_find_startmarker(mxg->buffer_ptr, search_end);
158  if (startmarker_ptr >= search_end - 1 ||
159  *(startmarker_ptr + 1) != EOI) break;
160  }
161 
162  if (startmarker_ptr != search_end) { /* start marker found */
163  marker = *(startmarker_ptr + 1);
164  mxg->buffer_ptr = startmarker_ptr + 2;
165  mxg->cache_size = end - mxg->buffer_ptr;
166 
167  if (marker == SOI) {
168  mxg->soi_ptr = startmarker_ptr;
169  } else if (marker == EOI) {
170  if (!mxg->soi_ptr) {
171  av_log(s, AV_LOG_WARNING, "Found EOI before SOI, skipping\n");
172  continue;
173  }
174 
175  size = mxg->buffer_ptr - mxg->soi_ptr;
176  ret = av_new_packet(pkt, size);
177  if (ret < 0)
178  return ret;
179  memcpy(pkt->data, mxg->soi_ptr, size);
180 
181  pkt->pts = pkt->dts = mxg->dts;
182  pkt->stream_index = 0;
183 
184  if (mxg->soi_ptr - mxg->buffer > mxg->cache_size) {
185  if (mxg->cache_size > 0) {
186  memmove(mxg->buffer, mxg->buffer_ptr, mxg->cache_size);
187  }
188 
189  mxg->buffer_ptr = mxg->buffer;
190  }
191  mxg->soi_ptr = 0;
192 
193  return pkt->size;
194  } else if ( (SOF0 <= marker && marker <= SOF15) ||
195  (SOS <= marker && marker <= COM) ) {
196  /* all other markers that start marker segment also contain
197  length value (see specification for JPEG Annex B.1) */
198  size = AV_RB16(mxg->buffer_ptr);
199  if (size < 2)
200  return AVERROR(EINVAL);
201 
202  if (mxg->cache_size < size) {
203  ret = mxg_update_cache(s, size);
204  if (ret < 0)
205  return ret;
206  startmarker_ptr = mxg->buffer_ptr - 2;
207  mxg->cache_size = 0;
208  } else {
209  mxg->cache_size -= size;
210  }
211 
212  mxg->buffer_ptr += size;
213 
214  if (marker == APP13 && size >= 16) { /* audio data */
215  ret = av_new_packet(pkt, size - 14);
216  if (ret < 0)
217  return ret;
218  memcpy(pkt->data, startmarker_ptr + 16, size - 14);
219 
220  /* time (GMT) of first sample in usec since 1970, little-endian */
221  pkt->pts = pkt->dts = AV_RL64(startmarker_ptr + 8);
222  pkt->stream_index = 1;
223 
224  if (startmarker_ptr - mxg->buffer > mxg->cache_size) {
225  if (mxg->cache_size > 0) {
226  memcpy(mxg->buffer, mxg->buffer_ptr, mxg->cache_size);
227  }
228  mxg->buffer_ptr = mxg->buffer;
229  }
230 
231  return pkt->size;
232  } else if (marker == COM && size >= 18 &&
233  !strncmp(startmarker_ptr + 4, "MXF", 3)) {
234  /* time (GMT) of video frame in usec since 1970, little-endian */
235  mxg->dts = AV_RL64(startmarker_ptr + 12);
236  }
237  }
238  } else {
239  /* start marker not found */
240  mxg->buffer_ptr = search_end;
241  mxg->cache_size = OVERREAD_SIZE;
242  }
243  }
244 
245  return AVERROR_EOF;
246 }
247 
248  static int mxg_close(struct AVFormatContext *s)
249 {
250  MXGContext *mxg = s->priv_data;
251  av_freep(&mxg->buffer);
252  return 0;
253 }
254 
255  const FFInputFormat ff_mxg_demuxer = {
256  .p.name = "mxg",
257  .p.long_name = NULL_IF_CONFIG_SMALL("MxPEG clip"),
258  .p.extensions = "mxg",
259  .priv_data_size = sizeof(MXGContext),
260  .read_header = mxg_read_header,
261  .read_packet = mxg_read_packet,
262  .read_close = mxg_close,
263 };
ff_mxg_demuxer
const FFInputFormat ff_mxg_demuxer
Definition: mxg.c:255
AV_LOG_WARNING
#define AV_LOG_WARNING
Something somehow does not look correct.
Definition: log.h:216
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
AVCodecParameters::codec_type
enum AVMediaType codec_type
General type of the encoded data.
Definition: codec_par.h:51
MXGContext::buffer_size
unsigned int buffer_size
Definition: mxg.c:39
SOS
@ SOS
Definition: mjpeg.h:72
avformat_new_stream
AVStream * avformat_new_stream(AVFormatContext *s, const struct AVCodec *c)
Add a new stream to a media file.
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
int64_t
long long int64_t
Definition: coverity.c:34
AVPacket::data
uint8_t * data
Definition: packet.h:558
mxg_read_header
static int mxg_read_header(AVFormatContext *s)
Definition: mxg.c:44
AV_CODEC_ID_MXPEG
@ AV_CODEC_ID_MXPEG
Definition: codec_id.h:198
MXGContext::buffer
uint8_t * buffer
Definition: mxg.c:36
mxg_update_cache
static int mxg_update_cache(AVFormatContext *s, unsigned int cache_size)
Definition: mxg.c:101
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:777
mxg_find_startmarker
static uint8_t * mxg_find_startmarker(uint8_t *p, uint8_t *end)
Definition: mxg.c:76
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:60
COM
@ COM
Definition: mjpeg.h:111
read_packet
static int read_packet(void *opaque, uint8_t *buf, int buf_size)
Definition: avio_read_callback.c:42
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:497
intreadwrite.h
s
#define s(width, name)
Definition: cbs_vp9.c:198
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: packet.c:99
AVInputFormat::name
const char * name
A comma separated list of short names for the format.
Definition: avformat.h:549
AVMEDIA_TYPE_AUDIO
@ AVMEDIA_TYPE_AUDIO
Definition: avutil.h:201
MXGContext::cache_size
unsigned int cache_size
Definition: mxg.c:41
MXGContext::buffer_ptr
uint8_t * buffer_ptr
Definition: mxg.c:37
OVERREAD_SIZE
#define OVERREAD_SIZE
Definition: mxg.c:33
MXGContext::dts
int64_t dts
Definition: mxg.c:40
AVFormatContext
Format I/O context.
Definition: avformat.h:1264
AV_CODEC_ID_PCM_ALAW
@ AV_CODEC_ID_PCM_ALAW
Definition: codec_id.h:344
internal.h
AVStream::codecpar
AVCodecParameters * codecpar
Codec parameters associated with this stream.
Definition: avformat.h:767
NULL
#define NULL
Definition: coverity.c:32
AV_RN32
#define AV_RN32(p)
Definition: intreadwrite.h:360
AVCodecParameters::ch_layout
AVChannelLayout ch_layout
Audio only.
Definition: codec_par.h:180
audio_st
AVStream * audio_st
Definition: movenc.c:61
AVCodecParameters::sample_rate
int sample_rate
Audio only.
Definition: codec_par.h:184
AVPacket::size
int size
Definition: packet.h:559
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:94
AVChannelLayout
An AVChannelLayout holds information about the channel layout of audio data.
Definition: channel_layout.h:319
MXGContext::soi_ptr
uint8_t * soi_ptr
Definition: mxg.c:38
size
int size
Definition: twinvq_data.h:10344
avio.h
video_st
AVStream * video_st
Definition: movenc.c:61
AV_NOPTS_VALUE
#define AV_NOPTS_VALUE
Undefined timestamp value.
Definition: avutil.h:247
SOF15
@ SOF15
Definition: mjpeg.h:54
FFInputFormat::p
AVInputFormat p
The public AVInputFormat.
Definition: demux.h:51
AVPacket::dts
int64_t dts
Decompression timestamp in AVStream->time_base units; the time at which the packet is decompressed.
Definition: packet.h:557
read_header
static int read_header(FFV1Context *f, RangeCoder *c)
Definition: ffv1dec.c:498
AVPacket::pts
int64_t pts
Presentation timestamp in AVStream->time_base units; the time at which the decompressed packet will b...
Definition: packet.h:551
EOI
@ EOI
Definition: mjpeg.h:71
internal.h
AVCodecParameters::block_align
int block_align
Audio only.
Definition: codec_par.h:191
mxg_read_packet
static int mxg_read_packet(AVFormatContext *s, AVPacket *pkt)
Definition: mxg.c:135
demux.h
MXGContext
Definition: mxg.c:35
ret
ret
Definition: filter_design.txt:187
AVStream
Stream structure.
Definition: avformat.h:744
mxg_close
static int mxg_close(struct AVFormatContext *s)
Definition: mxg.c:248
avformat.h
AV_INPUT_BUFFER_PADDING_SIZE
#define AV_INPUT_BUFFER_PADDING_SIZE
Definition: defs.h:40
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:615
Windows::Graphics::DirectX::Direct3D11::p
IDirect3DDxgiInterfaceAccess _COM_Outptr_ void ** p
Definition: vsrc_gfxcapture_winrt.hpp:53
AVPacket::stream_index
int stream_index
Definition: packet.h:560
AVMEDIA_TYPE_VIDEO
@ AVMEDIA_TYPE_VIDEO
Definition: avutil.h:200
AVCodecParameters::bits_per_coded_sample
int bits_per_coded_sample
The number of bits per sample in the codedwords.
Definition: codec_par.h:110
mem.h
SOI
@ SOI
Definition: mjpeg.h:70
AV_CHANNEL_LAYOUT_MONO
#define AV_CHANNEL_LAYOUT_MONO
Definition: channel_layout.h:394
DEFAULT_PACKET_SIZE
#define DEFAULT_PACKET_SIZE
Definition: mxg.c:32
AVCodecParameters::codec_id
enum AVCodecID codec_id
Specific type of the encoded data (the codec used).
Definition: codec_par.h:55
AVPacket
This structure stores compressed data.
Definition: packet.h:535
av_freep
#define av_freep(p)
Definition: tableprint_vlc.h:35
FFInputFormat
Definition: demux.h:47
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:349
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