rtpenc_h264.c
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1 /*
2  * RTP packetization for H.264 (RFC3984)
3  * Copyright (c) 2008 Luca Abeni
4  *
5  * This file is part of Libav.
6  *
7  * Libav 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  * Libav 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 Libav; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
28 #include "avformat.h"
29 #include "avc.h"
30 #include "rtpenc.h"
31 
32 static const uint8_t *avc_mp4_find_startcode(const uint8_t *start, const uint8_t *end, int nal_length_size)
33 {
34  int res = 0;
35 
36  if (end - start < nal_length_size)
37  return NULL;
38  while (nal_length_size--)
39  res = (res << 8) | *start++;
40 
41  if (start + res > end || res < 0 || start + res < start)
42  return NULL;
43 
44  return start + res;
45 }
46 
47 static void nal_send(AVFormatContext *s1, const uint8_t *buf, int size, int last)
48 {
49  RTPMuxContext *s = s1->priv_data;
50 
51  av_log(s1, AV_LOG_DEBUG, "Sending NAL %x of len %d M=%d\n", buf[0] & 0x1F, size, last);
52  if (size <= s->max_payload_size) {
53  ff_rtp_send_data(s1, buf, size, last);
54  } else {
55  uint8_t type = buf[0] & 0x1F;
56  uint8_t nri = buf[0] & 0x60;
57 
58  av_log(s1, AV_LOG_DEBUG, "NAL size %d > %d\n", size, s->max_payload_size);
59  s->buf[0] = 28; /* FU Indicator; Type = 28 ---> FU-A */
60  s->buf[0] |= nri;
61  s->buf[1] = type;
62  s->buf[1] |= 1 << 7;
63  buf += 1;
64  size -= 1;
65  while (size + 2 > s->max_payload_size) {
66  memcpy(&s->buf[2], buf, s->max_payload_size - 2);
67  ff_rtp_send_data(s1, s->buf, s->max_payload_size, 0);
68  buf += s->max_payload_size - 2;
69  size -= s->max_payload_size - 2;
70  s->buf[1] &= ~(1 << 7);
71  }
72  s->buf[1] |= 1 << 6;
73  memcpy(&s->buf[2], buf, size);
74  ff_rtp_send_data(s1, s->buf, size + 2, last);
75  }
76 }
77 
78 void ff_rtp_send_h264(AVFormatContext *s1, const uint8_t *buf1, int size)
79 {
80  const uint8_t *r, *end = buf1 + size;
81  RTPMuxContext *s = s1->priv_data;
82 
83  s->timestamp = s->cur_timestamp;
84  if (s->nal_length_size)
85  r = avc_mp4_find_startcode(buf1, end, s->nal_length_size) ? buf1 : end;
86  else
87  r = ff_avc_find_startcode(buf1, end);
88  while (r < end) {
89  const uint8_t *r1;
90 
91  if (s->nal_length_size) {
92  r1 = avc_mp4_find_startcode(r, end, s->nal_length_size);
93  if (!r1)
94  r1 = end;
95  r += s->nal_length_size;
96  } else {
97  while (!*(r++));
98  r1 = ff_avc_find_startcode(r, end);
99  }
100  nal_send(s1, r, r1 - r, r1 == end);
101  r = r1;
102  }
103 }