libavformat/rtp_mpv.c

   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/mpegvideo.h"
  24 #include "avformat.h"
  25 #include "rtp_internal.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     RTPDemuxContext *s = s1->priv_data;
  32     int len, h, max_packet_size;
  33     uint8_t *q;
  34     int begin_of_slice, end_of_slice, frame_type, temporal_reference;
  35
  36     max_packet_size = s->max_payload_size;
  37     begin_of_slice = 1;
  38     end_of_slice = 0;
  39     frame_type = 0;
  40     temporal_reference = 0;
  41
  42     while (size > 0) {
  43         int begin_of_sequence;
  44
  45         begin_of_sequence = 0;
  46         len = max_packet_size - 4;
  47
  48         if (len >= size) {
  49             len = size;
  50             end_of_slice = 1;
  51         } else {
  52             const uint8_t *r, *r1;
  53             int start_code;
  54
  55             r1 = buf1;
  56             while (1) {
  57                 start_code = -1;
  58                 r = ff_find_start_code(r1, buf1 + size, &start_code);
  59                 if((start_code & 0xFFFFFF00) == 0x100) {
  60                     /* New start code found */
  61                     if (start_code == 0x100) {
  62                         frame_type = (r[1] & 0x38) >> 3;
  63                         temporal_reference = (int)r[0] << 2 | r[1] >> 6;
  64                     }
  65                     if (start_code == 0x1B8) {
  66                         begin_of_sequence = 1;
  67                     }
  68
  69                     if (r - buf1 - 4 <= len) {
  70                         /* The current slice fits in the packet */
  71                         if (begin_of_slice == 0) {
  72                             /* no slice at the beginning of the packet... */
  73                             end_of_slice = 1;
  74                             len = r - buf1 - 4;
  75                             break;
  76                         }
  77                         r1 = r;
  78                     } else {
  79                         if ((r1 - buf1 > 4) && (r - r1 < max_packet_size)) {
  80                             len = r1 - buf1 - 4;
  81                             end_of_slice = 1;
  82                         }
  83                         break;
  84                     }
  85                 } else {
  86                     break;
  87                 }
  88             }
  89         }
  90
  91         h = 0;
  92         h |= temporal_reference << 16;
  93         h |= begin_of_sequence << 13;
  94         h |= begin_of_slice << 12;
  95         h |= end_of_slice << 11;
  96         h |= frame_type << 8;
  97
  98         q = s->buf;
  99         *q++ = h >> 24;
 100         *q++ = h >> 16;
 101         *q++ = h >> 8;
 102         *q++ = h;
 103
 104         memcpy(q, buf1, len);
 105         q += len;
 106
 107         /* 90 KHz time stamp */
 108         s->timestamp = s->cur_timestamp;
 109         ff_rtp_send_data(s1, s->buf, q - s->buf, (len == size));
 110
 111         buf1 += len;
 112         size -= len;
 113         begin_of_slice = end_of_slice;
 114         end_of_slice = 0;
 115     }
 116 }
 117
 118