1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
|
/*
* MxPEG clip file demuxer
* Copyright (c) 2010 Anatoly Nenashev
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "libavutil/channel_layout.h"
#include "libavutil/internal.h"
#include "libavutil/intreadwrite.h"
#include "libavcodec/mjpeg.h"
#include "avformat.h"
#include "internal.h"
#include "avio.h"
#define DEFAULT_PACKET_SIZE 1024
#define OVERREAD_SIZE 3
typedef struct MXGContext {
uint8_t *buffer;
uint8_t *buffer_ptr;
uint8_t *soi_ptr;
unsigned int buffer_size;
int64_t dts;
unsigned int cache_size;
} MXGContext;
static int mxg_read_header(AVFormatContext *s)
{
AVStream *video_st, *audio_st;
MXGContext *mxg = s->priv_data;
/* video parameters will be extracted from the compressed bitstream */
video_st = avformat_new_stream(s, NULL);
if (!video_st)
return AVERROR(ENOMEM);
video_st->codec->codec_type = AVMEDIA_TYPE_VIDEO;
video_st->codec->codec_id = AV_CODEC_ID_MXPEG;
avpriv_set_pts_info(video_st, 64, 1, 1000000);
audio_st = avformat_new_stream(s, NULL);
if (!audio_st)
return AVERROR(ENOMEM);
audio_st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
audio_st->codec->codec_id = AV_CODEC_ID_PCM_ALAW;
audio_st->codec->channels = 1;
audio_st->codec->channel_layout = AV_CH_LAYOUT_MONO;
audio_st->codec->sample_rate = 8000;
audio_st->codec->bits_per_coded_sample = 8;
audio_st->codec->block_align = 1;
avpriv_set_pts_info(audio_st, 64, 1, 1000000);
mxg->soi_ptr = mxg->buffer_ptr = mxg->buffer = 0;
mxg->buffer_size = 0;
mxg->dts = AV_NOPTS_VALUE;
mxg->cache_size = 0;
return 0;
}
static uint8_t* mxg_find_startmarker(uint8_t *p, uint8_t *end)
{
for (; p < end - 3; p += 4) {
uint32_t x = AV_RN32(p);
if (x & (~(x+0x01010101)) & 0x80808080) {
if (p[0] == 0xff) {
return p;
} else if (p[1] == 0xff) {
return p+1;
} else if (p[2] == 0xff) {
return p+2;
} else if (p[3] == 0xff) {
return p+3;
}
}
}
for (; p < end; ++p) {
if (*p == 0xff) return p;
}
return end;
}
static int mxg_update_cache(AVFormatContext *s, unsigned int cache_size)
{
MXGContext *mxg = s->priv_data;
unsigned int current_pos = mxg->buffer_ptr - mxg->buffer;
unsigned int soi_pos;
uint8_t *buffer;
int ret;
/* reallocate internal buffer */
if (current_pos > current_pos + cache_size)
return AVERROR(ENOMEM);
soi_pos = mxg->soi_ptr - mxg->buffer;
buffer = av_fast_realloc(mxg->buffer, &mxg->buffer_size,
current_pos + cache_size +
AV_INPUT_BUFFER_PADDING_SIZE);
if (!buffer)
return AVERROR(ENOMEM);
mxg->buffer = buffer;
mxg->buffer_ptr = mxg->buffer + current_pos;
if (mxg->soi_ptr) mxg->soi_ptr = mxg->buffer + soi_pos;
/* get data */
ret = avio_read(s->pb, mxg->buffer_ptr + mxg->cache_size,
cache_size - mxg->cache_size);
if (ret < 0)
return ret;
mxg->cache_size += ret;
return ret;
}
static int mxg_read_packet(AVFormatContext *s, AVPacket *pkt)
{
int ret;
unsigned int size;
uint8_t *startmarker_ptr, *end, *search_end, marker;
MXGContext *mxg = s->priv_data;
while (!avio_feof(s->pb) && !s->pb->error){
if (mxg->cache_size <= OVERREAD_SIZE) {
/* update internal buffer */
ret = mxg_update_cache(s, DEFAULT_PACKET_SIZE + OVERREAD_SIZE);
if (ret < 0)
return ret;
}
end = mxg->buffer_ptr + mxg->cache_size;
/* find start marker - 0xff */
if (mxg->cache_size > OVERREAD_SIZE) {
search_end = end - OVERREAD_SIZE;
startmarker_ptr = mxg_find_startmarker(mxg->buffer_ptr, search_end);
} else {
search_end = end;
startmarker_ptr = mxg_find_startmarker(mxg->buffer_ptr, search_end);
if (startmarker_ptr >= search_end - 1 ||
*(startmarker_ptr + 1) != EOI) break;
}
if (startmarker_ptr != search_end) { /* start marker found */
marker = *(startmarker_ptr + 1);
mxg->buffer_ptr = startmarker_ptr + 2;
mxg->cache_size = end - mxg->buffer_ptr;
if (marker == SOI) {
mxg->soi_ptr = startmarker_ptr;
} else if (marker == EOI) {
if (!mxg->soi_ptr) {
av_log(s, AV_LOG_WARNING, "Found EOI before SOI, skipping\n");
continue;
}
pkt->pts = pkt->dts = mxg->dts;
pkt->stream_index = 0;
pkt->buf = NULL;
pkt->size = mxg->buffer_ptr - mxg->soi_ptr;
pkt->data = mxg->soi_ptr;
if (mxg->soi_ptr - mxg->buffer > mxg->cache_size) {
if (mxg->cache_size > 0) {
memmove(mxg->buffer, mxg->buffer_ptr, mxg->cache_size);
}
mxg->buffer_ptr = mxg->buffer;
}
mxg->soi_ptr = 0;
return pkt->size;
} else if ( (SOF0 <= marker && marker <= SOF15) ||
(SOS <= marker && marker <= COM) ) {
/* all other markers that start marker segment also contain
length value (see specification for JPEG Annex B.1) */
size = AV_RB16(mxg->buffer_ptr);
if (size < 2)
return AVERROR(EINVAL);
if (mxg->cache_size < size) {
ret = mxg_update_cache(s, size);
if (ret < 0)
return ret;
startmarker_ptr = mxg->buffer_ptr - 2;
mxg->cache_size = 0;
} else {
mxg->cache_size -= size;
}
mxg->buffer_ptr += size;
if (marker == APP13 && size >= 16) { /* audio data */
/* time (GMT) of first sample in usec since 1970, little-endian */
pkt->pts = pkt->dts = AV_RL64(startmarker_ptr + 8);
pkt->stream_index = 1;
pkt->buf = NULL;
pkt->size = size - 14;
pkt->data = startmarker_ptr + 16;
if (startmarker_ptr - mxg->buffer > mxg->cache_size) {
if (mxg->cache_size > 0) {
memcpy(mxg->buffer, mxg->buffer_ptr, mxg->cache_size);
}
mxg->buffer_ptr = mxg->buffer;
}
return pkt->size;
} else if (marker == COM && size >= 18 &&
!strncmp(startmarker_ptr + 4, "MXF", 3)) {
/* time (GMT) of video frame in usec since 1970, little-endian */
mxg->dts = AV_RL64(startmarker_ptr + 12);
}
}
} else {
/* start marker not found */
mxg->buffer_ptr = search_end;
mxg->cache_size = OVERREAD_SIZE;
}
}
return AVERROR_EOF;
}
static int mxg_close(struct AVFormatContext *s)
{
MXGContext *mxg = s->priv_data;
av_freep(&mxg->buffer);
return 0;
}
AVInputFormat ff_mxg_demuxer = {
.name = "mxg",
.long_name = NULL_IF_CONFIG_SMALL("MxPEG clip"),
.priv_data_size = sizeof(MXGContext),
.read_header = mxg_read_header,
.read_packet = mxg_read_packet,
.read_close = mxg_close,
.extensions = "mxg",
};
|
