Libav
rtpenc_xiph.c
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1 /*
2  * RTP packetization for Xiph audio and video
3  * Copyright (c) 2010 Josh Allmann
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 
22 #include "libavutil/intreadwrite.h"
23 
24 #include "avformat.h"
25 #include "rtpenc.h"
26 
32 void ff_rtp_send_xiph(AVFormatContext *s1, const uint8_t *buff, int size)
33 {
34  RTPMuxContext *s = s1->priv_data;
35  AVStream *st = s1->streams[0];
36  int max_pkt_size, xdt, frag;
37  uint8_t *q;
38 
39  max_pkt_size = s->max_payload_size - 6; // ident+frag+tdt/vdt+pkt_num+pkt_length
40 
41  // set xiph data type
42  switch (*buff) {
43  case 0x01: // vorbis id
44  case 0x05: // vorbis setup
45  case 0x80: // theora header
46  case 0x82: // theora tables
47  xdt = 1; // packed config payload
48  break;
49  case 0x03: // vorbis comments
50  case 0x81: // theora comments
51  xdt = 2; // comment payload
52  break;
53  default:
54  xdt = 0; // raw data payload
55  break;
56  }
57 
58  // Set ident.
59  // Probably need a non-fixed way of generating
60  // this, but it has to be done in SDP and passed in from there.
61  q = s->buf;
62  *q++ = (RTP_XIPH_IDENT >> 16) & 0xff;
63  *q++ = (RTP_XIPH_IDENT >> 8) & 0xff;
64  *q++ = (RTP_XIPH_IDENT ) & 0xff;
65 
66  // set fragment
67  // 0 - whole frame (possibly multiple frames)
68  // 1 - first fragment
69  // 2 - fragment continuation
70  // 3 - last fragment
71  frag = size <= max_pkt_size ? 0 : 1;
72 
73  if (!frag && !xdt) { // do we have a whole frame of raw data?
74  uint8_t *end_ptr = s->buf + 6 + max_pkt_size; // what we're allowed to write
75  uint8_t *ptr = s->buf_ptr + 2 + size; // what we're going to write
76  int remaining = end_ptr - ptr;
77 
78  assert(s->num_frames <= s->max_frames_per_packet);
79  if (s->num_frames > 0 &&
80  (remaining < 0 ||
83  s1->max_delay, AV_TIME_BASE_Q) >= 0)) {
84  // send previous packets now; no room for new data, or too much delay
85  ff_rtp_send_data(s1, s->buf, s->buf_ptr - s->buf, 0);
86  s->num_frames = 0;
87  }
88 
89  // buffer current frame to send later
90  if (0 == s->num_frames)
91  s->timestamp = s->cur_timestamp;
92  s->num_frames++;
93 
94  // Set packet header. Normally, this is OR'd with frag and xdt,
95  // but those are zero, so omitted here
96  *q++ = s->num_frames;
97 
98  if (s->num_frames > 1)
99  q = s->buf_ptr; // jump ahead if needed
100  AV_WB16(q, size);
101  q += 2;
102  memcpy(q, buff, size);
103  q += size;
104  s->buf_ptr = q;
105 
106  return;
107  } else if (s->num_frames) {
108  // immediately send buffered frames if buffer is not raw data,
109  // or if current frame is fragmented.
110  ff_rtp_send_data(s1, s->buf, s->buf_ptr - s->buf, 0);
111  }
112 
113  s->timestamp = s->cur_timestamp;
114  s->num_frames = 0;
115  s->buf_ptr = q;
116  while (size > 0) {
117  int len = (!frag || frag == 3) ? size : max_pkt_size;
118  q = s->buf_ptr;
119 
120  // set packet headers
121  *q++ = (frag << 6) | (xdt << 4); // num_frames = 0
122  AV_WB16(q, len);
123  q += 2;
124  // set packet body
125  memcpy(q, buff, len);
126  q += len;
127  buff += len;
128  size -= len;
129 
130  ff_rtp_send_data(s1, s->buf, q - s->buf, 0);
131 
132  frag = size <= max_pkt_size ? 3 : 2;
133  }
134 }
int size
int max_payload_size
Definition: rtpenc.h:38
Format I/O context.
Definition: avformat.h:940
uint8_t
int max_frames_per_packet
Definition: rtpenc.h:52
AVStream ** streams
A list of all streams in the file.
Definition: avformat.h:1008
uint8_t * buf
Definition: rtpenc.h:49
int av_compare_ts(int64_t ts_a, AVRational tb_a, int64_t ts_b, AVRational tb_b)
Compare 2 timestamps each in its own timebases.
Definition: mathematics.c:104
void ff_rtp_send_data(AVFormatContext *s1, const uint8_t *buf1, int len, int m)
Definition: rtpenc.c:303
Stream structure.
Definition: avformat.h:705
uint32_t cur_timestamp
Definition: rtpenc.h:37
#define AV_TIME_BASE_Q
Internal time base represented as fractional value.
Definition: avutil.h:247
int num_frames
Definition: rtpenc.h:39
uint8_t * buf_ptr
Definition: rtpenc.h:50
#define RTP_XIPH_IDENT
Definition: rtp.h:89
Main libavformat public API header.
void ff_rtp_send_xiph(AVFormatContext *s1, const uint8_t *buff, int size)
Packetize Xiph frames into RTP according to RFC 5215 (Vorbis) and the Theora RFC draft.
Definition: rtpenc_xiph.c:32
uint32_t timestamp
Definition: rtpenc.h:35
int len
void * priv_data
Format private data.
Definition: avformat.h:968
AVRational time_base
This is the fundamental unit of time (in seconds) in terms of which frame timestamps are represented...
Definition: avformat.h:742
#define AV_WB16(p, val)
Definition: intreadwrite.h:218