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 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  */
  33 void ff_rtp_send_xiph(AVFormatContext *s1, const uint8_t *buff, int size)
  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 fragment
  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
  79         av_assert1(s->num_frames <= s->max_frames_per_packet);
  80         if (s->num_frames > 0 &&
  81             (remaining < 0 ||
  82              s->num_frames == s->max_frames_per_packet ||
  83              av_compare_ts(s->cur_timestamp - s->timestamp, st->time_base,
  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 }