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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 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 "libavutil/avassert.h"
23 #include "libavutil/intreadwrite.h"
24 
25 #include "avformat.h"
26 #include "rtpenc.h"
27 
28 /**
29  * Packetize Xiph frames into RTP according to
30  * RFC 5215 (Vorbis) and the Theora RFC draft.
31  * (http://svn.xiph.org/trunk/theora/doc/draft-ietf-avt-rtp-theora-00.txt)
32  */
34 {
35  RTPMuxContext *s = s1->priv_data;
36  AVStream *st = s1->streams[0];
37  int max_pkt_size, xdt, frag;
38  uint8_t *q;
39 
40  max_pkt_size = s->max_payload_size - 6; // ident+frag+tdt/vdt+pkt_num+pkt_length
41 
42  // set xiph data type
43  switch (*buff) {
44  case 0x01: // vorbis id
45  case 0x05: // vorbis setup
46  case 0x80: // theora header
47  case 0x82: // theora tables
48  xdt = 1; // packed config payload
49  break;
50  case 0x03: // vorbis comments
51  case 0x81: // theora comments
52  xdt = 2; // comment payload
53  break;
54  default:
55  xdt = 0; // raw data payload
56  break;
57  }
58 
59  // Set ident.
60  // Probably need a non-fixed way of generating
61  // this, but it has to be done in SDP and passed in from there.
62  q = s->buf;
63  *q++ = (RTP_XIPH_IDENT >> 16) & 0xff;
64  *q++ = (RTP_XIPH_IDENT >> 8) & 0xff;
65  *q++ = (RTP_XIPH_IDENT ) & 0xff;
66 
67  // set fragment
68  // 0 - whole frame (possibly multiple frames)
69  // 1 - first fragment
70  // 2 - fragment continuation
71  // 3 - last fragmement
72  frag = size <= max_pkt_size ? 0 : 1;
73 
74  if (!frag && !xdt) { // do we have a whole frame of raw data?
75  uint8_t *end_ptr = s->buf + 6 + max_pkt_size; // what we're allowed to write
76  uint8_t *ptr = s->buf_ptr + 2 + size; // what we're going to write
77  int remaining = end_ptr - ptr;
78 
80  if (s->num_frames > 0 &&
81  (remaining < 0 ||
84  s1->max_delay, AV_TIME_BASE_Q) >= 0)) {
85  // send previous packets now; no room for new data, or too much delay
86  ff_rtp_send_data(s1, s->buf, s->buf_ptr - s->buf, 0);
87  s->num_frames = 0;
88  }
89 
90  // buffer current frame to send later
91  if (0 == s->num_frames)
92  s->timestamp = s->cur_timestamp;
93  s->num_frames++;
94 
95  // Set packet header. Normally, this is OR'd with frag and xdt,
96  // but those are zero, so omitted here
97  *q++ = s->num_frames;
98 
99  if (s->num_frames > 1)
100  q = s->buf_ptr; // jump ahead if needed
101  AV_WB16(q, size);
102  q += 2;
103  memcpy(q, buff, size);
104  q += size;
105  s->buf_ptr = q;
106 
107  return;
108  } else if (s->num_frames) {
109  // immediately send buffered frames if buffer is not raw data,
110  // or if current frame is fragmented.
111  ff_rtp_send_data(s1, s->buf, s->buf_ptr - s->buf, 0);
112  }
113 
114  s->timestamp = s->cur_timestamp;
115  s->num_frames = 0;
116  s->buf_ptr = q;
117  while (size > 0) {
118  int len = (!frag || frag == 3) ? size : max_pkt_size;
119  q = s->buf_ptr;
120 
121  // set packet headers
122  *q++ = (frag << 6) | (xdt << 4); // num_frames = 0
123  AV_WB16(q, len);
124  q += 2;
125  // set packet body
126  memcpy(q, buff, len);
127  q += len;
128  buff += len;
129  size -= len;
130 
131  ff_rtp_send_data(s1, s->buf, q - s->buf, 0);
132 
133  frag = size <= max_pkt_size ? 3 : 2;
134  }
135 }
const char * s
Definition: avisynth_c.h:631
int max_payload_size
Definition: rtpenc.h:38
Format I/O context.
Definition: avformat.h:1319
uint8_t
int max_frames_per_packet
Definition: rtpenc.h:52
AVStream ** streams
A list of all streams in the file.
Definition: avformat.h:1387
uint8_t * buf
Definition: rtpenc.h:49
ptrdiff_t size
Definition: opengl_enc.c:101
#define AV_WB16(p, v)
Definition: intreadwrite.h:405
simple assert() macros that are a bit more flexible than ISO C assert().
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:147
#define av_assert1(cond)
assert() equivalent, that does not lie in speed critical code.
Definition: avassert.h:53
void ff_rtp_send_data(AVFormatContext *s1, const uint8_t *buf1, int len, int m)
Definition: rtpenc.c:319
Stream structure.
Definition: avformat.h:876
uint32_t cur_timestamp
Definition: rtpenc.h:37
#define AV_TIME_BASE_Q
Internal time base represented as fractional value.
Definition: avutil.h:252
#define s1
Definition: regdef.h:38
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:33
uint32_t timestamp
Definition: rtpenc.h:35
int len
void * priv_data
Format private data.
Definition: avformat.h:1347
AVRational time_base
This is the fundamental unit of time (in seconds) in terms of which frame timestamps are represented...
Definition: avformat.h:913