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rtpenc_jpeg.c
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1 /*
2  * RTP JPEG-compressed video Packetizer, RFC 2435
3  * Copyright (c) 2012 Samuel Pitoiset
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 "libavcodec/bytestream.h"
23 #include "libavcodec/mjpeg.h"
24 #include "libavutil/intreadwrite.h"
25 #include "rtpenc.h"
26 
28 {
29  RTPMuxContext *s = s1->priv_data;
30  const uint8_t *qtables = NULL;
31  int nb_qtables = 0;
32  uint8_t type = 1; /* default pixel format is AV_PIX_FMT_YUVJ420P */
33  uint8_t w, h;
34  uint8_t *p;
35  int off = 0; /* fragment offset of the current JPEG frame */
36  int len;
37  int i;
38 
39  s->buf_ptr = s->buf;
40  s->timestamp = s->cur_timestamp;
41 
42  /* convert video pixel dimensions from pixels to blocks */
43  w = s1->streams[0]->codec->width >> 3;
44  h = s1->streams[0]->codec->height >> 3;
45 
46  /* check if pixel format is not the normal 420 case */
47  if (s1->streams[0]->codec->pix_fmt == AV_PIX_FMT_YUVJ422P) {
48  type = 0;
49  } else if (s1->streams[0]->codec->pix_fmt == AV_PIX_FMT_YUVJ420P) {
50  type = 1;
51  } else {
52  av_log(s1, AV_LOG_ERROR, "Unsupported pixel format\n");
53  return;
54  }
55 
56  /* preparse the header for getting some infos */
57  for (i = 0; i < size; i++) {
58  if (buf[i] != 0xff)
59  continue;
60 
61  if (buf[i + 1] == DQT) {
62  if (buf[i + 4])
64  "Only 8-bit precision is supported.\n");
65 
66  /* a quantization table is 64 bytes long */
67  nb_qtables = AV_RB16(&buf[i + 2]) / 65;
68  if (i + 4 + nb_qtables * 65 > size) {
69  av_log(s1, AV_LOG_ERROR, "Too short JPEG header. Aborted!\n");
70  return;
71  }
72 
73  qtables = &buf[i + 4];
74  } else if (buf[i + 1] == SOF0) {
75  if (buf[i + 14] != 17 || buf[i + 17] != 17) {
76  av_log(s1, AV_LOG_ERROR,
77  "Only 1x1 chroma blocks are supported. Aborted!\n");
78  return;
79  }
80  } else if (buf[i + 1] == SOS) {
81  /* SOS is last marker in the header */
82  i += AV_RB16(&buf[i + 2]) + 2;
83  break;
84  }
85  }
86 
87  /* skip JPEG header */
88  buf += i;
89  size -= i;
90 
91  for (i = size - 2; i >= 0; i--) {
92  if (buf[i] == 0xff && buf[i + 1] == EOI) {
93  /* Remove the EOI marker */
94  size = i;
95  break;
96  }
97  }
98 
99  p = s->buf_ptr;
100  while (size > 0) {
101  int hdr_size = 8;
102 
103  if (off == 0 && nb_qtables)
104  hdr_size += 4 + 64 * nb_qtables;
105 
106  /* payload max in one packet */
107  len = FFMIN(size, s->max_payload_size - hdr_size);
108 
109  /* set main header */
110  bytestream_put_byte(&p, 0);
111  bytestream_put_be24(&p, off);
112  bytestream_put_byte(&p, type);
113  bytestream_put_byte(&p, 255);
114  bytestream_put_byte(&p, w);
115  bytestream_put_byte(&p, h);
116 
117  if (off == 0 && nb_qtables) {
118  /* set quantization tables header */
119  bytestream_put_byte(&p, 0);
120  bytestream_put_byte(&p, 0);
121  bytestream_put_be16(&p, 64 * nb_qtables);
122 
123  for (i = 0; i < nb_qtables; i++)
124  bytestream_put_buffer(&p, &qtables[65 * i + 1], 64);
125  }
126 
127  /* copy payload data */
128  memcpy(p, buf, len);
129 
130  /* marker bit is last packet in frame */
131  ff_rtp_send_data(s1, s->buf, len + hdr_size, size == len);
132 
133  buf += len;
134  size -= len;
135  off += len;
136  p = s->buf;
137  }
138 }