/*
  * RTP packetization for Xiph audio and video
  * Copyright (c) 2010 Josh Allmann
  *
  * This file is part of FFmpeg.
  *
  * FFmpeg is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
  * FFmpeg is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
  * License along with FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 

 #include "libavutil/avassert.h"

 #include "avformat.h"
 #include "rtpenc.h"
 
 /**
  * Packetize Xiph frames into RTP according to
  * RFC 5215 (Vorbis) and the Theora RFC draft.
  * (http://svn.xiph.org/trunk/theora/doc/draft-ietf-avt-rtp-theora-00.txt)
  */
 void ff_rtp_send_xiph(AVFormatContext *s1, const uint8_t *buff, int size)
 {
     RTPMuxContext *s = s1->priv_data;
     int max_pkt_size, xdt, frag;
     uint8_t *q;
 
     max_pkt_size = s->max_payload_size;
 
     // set xiph data type
     switch (*buff) {
     case 0x01:   // vorbis id
     case 0x05:   // vorbis setup
     case 0x80:   // theora header
     case 0x82:   // theora tables
         xdt = 1; // packed config payload
         break;
     case 0x03:   // vorbis comments
     case 0x81:   // theora comments
         xdt = 2; // comment payload
         break;
     default:
         xdt = 0; // raw data payload
         break;
     }
 

     // Set ident.

     // Probably need a non-fixed way of generating
     // this, but it has to be done in SDP and passed in from there.
     q = s->buf;

     *q++ = (RTP_XIPH_IDENT >> 16) & 0xff;
     *q++ = (RTP_XIPH_IDENT >>  8) & 0xff;
     *q++ = (RTP_XIPH_IDENT      ) & 0xff;

 
     // set fragment
     // 0 - whole frame (possibly multiple frames)
     // 1 - first fragment
     // 2 - fragment continuation
     // 3 - last fragmement
     frag = size <= max_pkt_size ? 0 : 1;
 
     if (!frag && !xdt) { // do we have a whole frame of raw data?

         uint8_t *end_ptr = s->buf + 6 + max_pkt_size; // what we're allowed to write
         uint8_t *ptr     = s->buf_ptr + 2 + size; // what we're going to write

         int remaining    = end_ptr - ptr;
 

         av_assert1(s->num_frames <= s->max_frames_per_packet);

         if ((s->num_frames > 0 && remaining < 0) ||

             s->num_frames == s->max_frames_per_packet) {

             // send previous packets now; no room for new data
             ff_rtp_send_data(s1, s->buf, s->buf_ptr - s->buf, 0);
             s->num_frames = 0;
         }
 
         // buffer current frame to send later
         if (0 == s->num_frames) s->timestamp = s->cur_timestamp;
         s->num_frames++;
 
         // Set packet header. Normally, this is OR'd with frag and xdt,
         // but those are zero, so omitted here
         *q++ = s->num_frames;
 
         if (s->num_frames > 1) q = s->buf_ptr; // jump ahead if needed
         *q++ = (size >> 8) & 0xff;
         *q++ = size & 0xff;
         memcpy(q, buff, size);
         q += size;
         s->buf_ptr = q;
 
         return;
     } else if (s->num_frames) {
         // immediately send buffered frames if buffer is not raw data,
         // or if current frame is fragmented.
         ff_rtp_send_data(s1, s->buf, s->buf_ptr - s->buf, 0);
     }
 
     s->timestamp = s->cur_timestamp;
     s->num_frames = 0;
     s->buf_ptr = q;
     while (size > 0) {
         int len = (!frag || frag == 3) ? size : max_pkt_size;
         q = s->buf_ptr;
 
         // set packet headers
         *q++ = (frag << 6) | (xdt << 4); // num_frames = 0
         *q++ = (len >> 8) & 0xff;
         *q++ = len & 0xff;
         // set packet body
         memcpy(q, buff, len);
         q += len;
         buff += len;
         size -= len;
 
         ff_rtp_send_data(s1, s->buf, q - s->buf, 0);
 
         frag = size <= max_pkt_size ? 3 : 2;
     }
 }