libavformat/rtp_aac.c

   1 /*
   2  * copyright (c) 2007 Luca Abeni
   3  *
   4  * This file is part of FFmpeg.
   5  *
   6  * FFmpeg is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2.1 of the License, or (at your option) any later version.
  10  *
  11  * FFmpeg is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with FFmpeg; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  19  */
  20
  21 #include "avformat.h"
  22 #include "rtpenc.h"
  23
  24
  25 void ff_rtp_send_aac(AVFormatContext *s1, const uint8_t *buff, int size)
  26 {
  27     RTPMuxContext *s = s1->priv_data;
  28     int len, max_packet_size;
  29     uint8_t *p;
  30     const int max_frames_per_packet = s->max_frames_per_packet ? s->max_frames_per_packet : 5;
  31     const int max_au_headers_size = 2 + 2 * max_frames_per_packet;
  32
  33     /* skip ADTS header, if present */
  34     if ((s1->streams[0]->codec->extradata_size) == 0) {
  35         size -= 7;
  36         buff += 7;
  37     }
  38     max_packet_size = s->max_payload_size - max_au_headers_size;
  39
  40     /* test if the packet must be sent */
  41     len = (s->buf_ptr - s->buf);
  42     if ((s->num_frames == max_frames_per_packet) || (len && (len + size) > s->max_payload_size)) {
  43         int au_size = s->num_frames * 2;
  44
  45         p = s->buf + max_au_headers_size - au_size - 2;
  46         if (p != s->buf) {
  47             memmove(p + 2, s->buf + 2, au_size);
  48         }
  49         /* Write the AU header size */
  50         p[0] = ((au_size * 8) & 0xFF) >> 8;
  51         p[1] = (au_size * 8) & 0xFF;
  52
  53         ff_rtp_send_data(s1, p, s->buf_ptr - p, 1);
  54
  55         s->num_frames = 0;
  56     }
  57     if (s->num_frames == 0) {
  58         s->buf_ptr = s->buf + max_au_headers_size;
  59         s->timestamp = s->cur_timestamp;
  60     }
  61
  62     if (size <= max_packet_size) {
  63         p = s->buf + s->num_frames++ * 2 + 2;
  64         *p++ = size >> 5;
  65         *p = (size & 0x1F) << 3;
  66         memcpy(s->buf_ptr, buff, size);
  67         s->buf_ptr += size;
  68     } else {
  69         int au_size = size;
  70
  71         max_packet_size = s->max_payload_size - 4;
  72         p = s->buf;
  73         p[0] = 0;
  74         p[1] = 16;
  75         while (size > 0) {
  76             len = FFMIN(size, max_packet_size);
  77             p[2] = au_size >> 5;
  78             p[3] = (au_size & 0x1F) << 3;
  79             memcpy(p + 4, buff, len);
  80             ff_rtp_send_data(s1, p, len + 4, len == size);
  81             size -= len;
  82             buff += len;
  83         }
  84     }
  85 }