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  1. /*
  2.  * RTP packetization for MPEG video
  3.  * Copyright (c) 2002 Fabrice Bellard
  4.  * Copyright (c) 2007 Luca Abeni
  5.  *
  6.  * This file is part of FFmpeg.
  7.  *
  8.  * FFmpeg is free software; you can redistribute it and/or
  9.  * modify it under the terms of the GNU Lesser General Public
  10.  * License as published by the Free Software Foundation; either
  11.  * version 2.1 of the License, or (at your option) any later version.
  12.  *
  13.  * FFmpeg is distributed in the hope that it will be useful,
  14.  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16.  * Lesser General Public License for more details.
  17.  *
  18.  * You should have received a copy of the GNU Lesser General Public
  19.  * License along with FFmpeg; if not, write to the Free Software
  20.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21.  */
  22.  
  23. #include "libavcodec/internal.h"
  24. #include "avformat.h"
  25. #include "rtpenc.h"
  26.  
  27. /* NOTE: a single frame must be passed with sequence header if
  28.    needed. XXX: use slices. */
  29. void ff_rtp_send_mpegvideo(AVFormatContext *s1, const uint8_t *buf1, int size)
  30. {
  31.     RTPMuxContext *s = s1->priv_data;
  32.     int len, h, max_packet_size;
  33.     uint8_t *q;
  34.     const uint8_t *end = buf1 + size;
  35.     int begin_of_slice, end_of_slice, frame_type, temporal_reference;
  36.  
  37.     max_packet_size = s->max_payload_size;
  38.     begin_of_slice = 1;
  39.     end_of_slice = 0;
  40.     frame_type = 0;
  41.     temporal_reference = 0;
  42.  
  43.     while (size > 0) {
  44.         int begin_of_sequence;
  45.  
  46.         begin_of_sequence = 0;
  47.         len = max_packet_size - 4;
  48.  
  49.         if (len >= size) {
  50.             len = size;
  51.             end_of_slice = 1;
  52.         } else {
  53.             const uint8_t *r, *r1;
  54.             int start_code;
  55.  
  56.             r1 = buf1;
  57.             while (1) {
  58.                 start_code = -1;
  59.                 r = avpriv_find_start_code(r1, end, &start_code);
  60.                 if((start_code & 0xFFFFFF00) == 0x100) {
  61.                     /* New start code found */
  62.                     if (start_code == 0x100) {
  63.                         frame_type = (r[1] & 0x38) >> 3;
  64.                         temporal_reference = (int)r[0] << 2 | r[1] >> 6;
  65.                     }
  66.                     if (start_code == 0x1B8) {
  67.                         begin_of_sequence = 1;
  68.                     }
  69.  
  70.                     if (r - buf1 - 4 <= len) {
  71.                         /* The current slice fits in the packet */
  72.                         if (begin_of_slice == 0) {
  73.                             /* no slice at the beginning of the packet... */
  74.                             end_of_slice = 1;
  75.                             len = r - buf1 - 4;
  76.                             break;
  77.                         }
  78.                         r1 = r;
  79.                     } else {
  80.                         if ((r1 - buf1 > 4) && (r - r1 < max_packet_size)) {
  81.                             len = r1 - buf1 - 4;
  82.                             end_of_slice = 1;
  83.                         }
  84.                         break;
  85.                     }
  86.                 } else {
  87.                     break;
  88.                 }
  89.             }
  90.         }
  91.  
  92.         h = 0;
  93.         h |= temporal_reference << 16;
  94.         h |= begin_of_sequence << 13;
  95.         h |= begin_of_slice << 12;
  96.         h |= end_of_slice << 11;
  97.         h |= frame_type << 8;
  98.  
  99.         q = s->buf;
  100.         *q++ = h >> 24;
  101.         *q++ = h >> 16;
  102.         *q++ = h >> 8;
  103.         *q++ = h;
  104.  
  105.         memcpy(q, buf1, len);
  106.         q += len;
  107.  
  108.         /* 90kHz time stamp */
  109.         s->timestamp = s->cur_timestamp;
  110.         ff_rtp_send_data(s1, s->buf, q - s->buf, (len == size));
  111.  
  112.         buf1 += len;
  113.         size -= len;
  114.         begin_of_slice = end_of_slice;
  115.         end_of_slice = 0;
  116.     }
  117. }
  118.