/*
  * RTP packetization for H.263 video
  * Copyright (c) 2009 Luca Abeni

  * Copyright (c) 2009 Martin Storsjo

  *
  * 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 "avformat.h"
 #include "rtpenc.h"
 

 const uint8_t *ff_h263_find_resync_marker_reverse(const uint8_t *restrict start,
                                                   const uint8_t *restrict end)

 {
     const uint8_t *p = end - 1;
     start += 1; /* Make sure we never return the original start. */
     for (; p > start; p -= 2) {
         if (!*p) {
             if      (!p[ 1] && p[2]) return p;
             else if (!p[-1] && p[1]) return p - 1;
         }
     }
     return end;
 }
 
 /**
  * Packetize H.263 frames into RTP packets according to RFC 4629
  */
 void ff_rtp_send_h263(AVFormatContext *s1, const uint8_t *buf1, int size)
 {
     RTPMuxContext *s = s1->priv_data;
     int len, max_packet_size;
     uint8_t *q;
 
     max_packet_size = s->max_payload_size;
 
     while (size > 0) {
         q = s->buf;

         if (size >= 2 && (buf1[0] == 0) && (buf1[1] == 0)) {

             *q++ = 0x04;
             buf1 += 2;
             size -= 2;
         } else {
             *q++ = 0;
         }
         *q++ = 0;
 
         len = FFMIN(max_packet_size - 2, size);
 
         /* Look for a better place to split the frame into packets. */
         if (len < size) {

             const uint8_t *end = ff_h263_find_resync_marker_reverse(buf1,
                                                                     buf1 + len);

             len = end - buf1;
         }
 
         memcpy(q, buf1, len);
         q += len;
 
         /* 90 KHz time stamp */
         s->timestamp = s->cur_timestamp;
         ff_rtp_send_data(s1, s->buf, q - s->buf, (len == size));
 
         buf1 += len;
         size -= len;
     }
 }