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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 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 /**
23  * @file
24  * @brief H.264 packetization
25  * @author Luca Abeni <lucabe72@email.it>
26  */
27 
28 #include "libavutil/intreadwrite.h"
29 
30 #include "avformat.h"
31 #include "avc.h"
32 #include "rtpenc.h"
33 
34 static void flush_buffered(AVFormatContext *s1, int last)
35 {
36  RTPMuxContext *s = s1->priv_data;
37  if (s->buf_ptr != s->buf) {
38  // If we're only sending one single NAL unit, send it as such, skip
39  // the STAP-A framing
40  if (s->buffered_nals == 1)
41  ff_rtp_send_data(s1, s->buf + 3, s->buf_ptr - s->buf - 3, last);
42  else
43  ff_rtp_send_data(s1, s->buf, s->buf_ptr - s->buf, last);
44  }
45  s->buf_ptr = s->buf;
46  s->buffered_nals = 0;
47 }
48 
49 static void nal_send(AVFormatContext *s1, const uint8_t *buf, int size, int last)
50 {
51  RTPMuxContext *s = s1->priv_data;
52 
53  av_log(s1, AV_LOG_DEBUG, "Sending NAL %x of len %d M=%d\n", buf[0] & 0x1F, size, last);
54  if (size <= s->max_payload_size) {
55  int buffered_size = s->buf_ptr - s->buf;
56  // Flush buffered NAL units if the current unit doesn't fit
57  if (buffered_size + 2 + size > s->max_payload_size) {
58  flush_buffered(s1, 0);
59  buffered_size = 0;
60  }
61  // If we aren't using mode 0, and the NAL unit fits including the
62  // framing (2 bytes length, plus 1 byte for the STAP-A marker),
63  // write the unit to the buffer as a STAP-A packet, otherwise flush
64  // and send as single NAL.
65  if (buffered_size + 3 + size <= s->max_payload_size &&
66  !(s->flags & FF_RTP_FLAG_H264_MODE0)) {
67  if (buffered_size == 0)
68  *s->buf_ptr++ = 24;
69  AV_WB16(s->buf_ptr, size);
70  s->buf_ptr += 2;
71  memcpy(s->buf_ptr, buf, size);
72  s->buf_ptr += size;
73  s->buffered_nals++;
74  } else {
75  flush_buffered(s1, 0);
76  ff_rtp_send_data(s1, buf, size, last);
77  }
78  } else {
79  uint8_t type = buf[0] & 0x1F;
80  uint8_t nri = buf[0] & 0x60;
81 
82  flush_buffered(s1, 0);
83  if (s->flags & FF_RTP_FLAG_H264_MODE0) {
84  av_log(s1, AV_LOG_ERROR,
85  "NAL size %d > %d, try -slice-max-size %d\n", size,
87  return;
88  }
89  av_log(s1, AV_LOG_DEBUG, "NAL size %d > %d\n", size, s->max_payload_size);
90  s->buf[0] = 28; /* FU Indicator; Type = 28 ---> FU-A */
91  s->buf[0] |= nri;
92  s->buf[1] = type;
93  s->buf[1] |= 1 << 7;
94  buf += 1;
95  size -= 1;
96  while (size + 2 > s->max_payload_size) {
97  memcpy(&s->buf[2], buf, s->max_payload_size - 2);
98  ff_rtp_send_data(s1, s->buf, s->max_payload_size, 0);
99  buf += s->max_payload_size - 2;
100  size -= s->max_payload_size - 2;
101  s->buf[1] &= ~(1 << 7);
102  }
103  s->buf[1] |= 1 << 6;
104  memcpy(&s->buf[2], buf, size);
105  ff_rtp_send_data(s1, s->buf, size + 2, last);
106  }
107 }
108 
110 {
111  const uint8_t *r, *end = buf1 + size;
112  RTPMuxContext *s = s1->priv_data;
113 
114  s->timestamp = s->cur_timestamp;
115  s->buf_ptr = s->buf;
116  if (s->nal_length_size)
117  r = ff_avc_mp4_find_startcode(buf1, end, s->nal_length_size) ? buf1 : end;
118  else
119  r = ff_avc_find_startcode(buf1, end);
120  while (r < end) {
121  const uint8_t *r1;
122 
123  if (s->nal_length_size) {
125  if (!r1)
126  r1 = end;
127  r += s->nal_length_size;
128  } else {
129  while (!*(r++));
130  r1 = ff_avc_find_startcode(r, end);
131  }
132  nal_send(s1, r, r1 - r, r1 == end);
133  r = r1;
134  }
135  flush_buffered(s1, 1);
136 }