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/libavformat/rtpenc_xiph.c

http://github.com/FFmpeg/FFmpeg
C | 135 lines | 76 code | 17 blank | 42 comment | 13 complexity | e3a497163577db04544f27310130003c MD5 | raw file
  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 */
 33void 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}