libavformat/rtpenc_xiph.c

   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 "avformat.h"
  23 #include "rtpenc.h"
  24
  25 /**
  26  * Packetize Xiph frames into RTP according to
  27  * RFC 5215 (Vorbis) and the Theora RFC draft.
  28  * (http://svn.xiph.org/trunk/theora/doc/draft-ietf-avt-rtp-theora-00.txt)
  29  */
  30 void ff_rtp_send_xiph(AVFormatContext *s1, const uint8_t *buff, int size)
  31 {
  32     RTPMuxContext *s = s1->priv_data;
  33     int max_pkt_size, xdt, frag;
  34     uint8_t *q;
  35
  36     max_pkt_size = s->max_payload_size;
  37
  38     // set xiph data type
  39     switch (*buff) {
  40     case 0x01:   // vorbis id
  41     case 0x05:   // vorbis setup
  42     case 0x80:   // theora header
  43     case 0x82:   // theora tables
  44         xdt = 1; // packed config payload
  45         break;
  46     case 0x03:   // vorbis comments
  47     case 0x81:   // theora comments
  48         xdt = 2; // comment payload
  49         break;
  50     default:
  51         xdt = 0; // raw data payload
  52         break;
  53     }
  54
  55     // Set ident.
  56     // Probably need a non-fixed way of generating
  57     // this, but it has to be done in SDP and passed in from there.
  58     q = s->buf;
  59     *q++ = (RTP_XIPH_IDENT >> 16) & 0xff;
  60     *q++ = (RTP_XIPH_IDENT >>  8) & 0xff;
  61     *q++ = (RTP_XIPH_IDENT      ) & 0xff;
  62
  63     // set fragment
  64     // 0 - whole frame (possibly multiple frames)
  65     // 1 - first fragment
  66     // 2 - fragment continuation
  67     // 3 - last fragmement
  68     frag = size <= max_pkt_size ? 0 : 1;
  69
  70     if (!frag && !xdt) { // do we have a whole frame of raw data?
  71         uint8_t *end_ptr = s->buf + 6 + max_pkt_size; // what we're allowed to write
  72         uint8_t *ptr     = s->buf_ptr + 2 + size; // what we're going to write
  73         int remaining    = end_ptr - ptr;
  74
  75         assert(s->num_frames <= s->max_frames_per_packet);
  76         if ((s->num_frames > 0 && remaining < 0) ||
  77             s->num_frames == s->max_frames_per_packet) {
  78             // send previous packets now; no room for new data
  79             ff_rtp_send_data(s1, s->buf, s->buf_ptr - s->buf, 0);
  80             s->num_frames = 0;
  81         }
  82
  83         // buffer current frame to send later
  84         if (0 == s->num_frames) s->timestamp = s->cur_timestamp;
  85         s->num_frames++;
  86
  87         // Set packet header. Normally, this is OR'd with frag and xdt,
  88         // but those are zero, so omitted here
  89         *q++ = s->num_frames;
  90
  91         if (s->num_frames > 1) q = s->buf_ptr; // jump ahead if needed
  92         *q++ = (size >> 8) & 0xff;
  93         *q++ = size & 0xff;
  94         memcpy(q, buff, size);
  95         q += size;
  96         s->buf_ptr = q;
  97
  98         return;
  99     } else if (s->num_frames) {
 100         // immediately send buffered frames if buffer is not raw data,
 101         // or if current frame is fragmented.
 102         ff_rtp_send_data(s1, s->buf, s->buf_ptr - s->buf, 0);
 103     }
 104
 105     s->timestamp = s->cur_timestamp;
 106     s->num_frames = 0;
 107     s->buf_ptr = q;
 108     while (size > 0) {
 109         int len = (!frag || frag == 3) ? size : max_pkt_size;
 110         q = s->buf_ptr;
 111
 112         // set packet headers
 113         *q++ = (frag << 6) | (xdt << 4); // num_frames = 0
 114         *q++ = (len >> 8) & 0xff;
 115         *q++ = len & 0xff;
 116         // set packet body
 117         memcpy(q, buff, len);
 118         q += len;
 119         buff += len;
 120         size -= len;
 121
 122         ff_rtp_send_data(s1, s->buf, q - s->buf, 0);
 123
 124         frag = size <= max_pkt_size ? 3 : 2;
 125     }
 126 }