libavformat/rtp_amr.c

   1 /*
   2  * RTP packetization for AMR audio
   3  * Copyright (c) 2007 Luca Abeni
   4  * Copyright (c) 2009 Martin Storsjo
   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 "avformat.h"
  24 #include "rtpenc.h"
  25
  26 /**
  27  * Packetize AMR frames into RTP packets according to RFC 3267,
  28  * in octet-aligned mode.
  29  */
  30 void ff_rtp_send_amr(AVFormatContext *s1, const uint8_t *buff, int size)
  31 {
  32     RTPMuxContext *s          = s1->priv_data;
  33     int max_header_toc_size   = 1 + s->max_frames_per_packet;
  34     uint8_t *p;
  35     int len;
  36
  37     /* Test if the packet must be sent. */
  38     len = s->buf_ptr - s->buf;
  39     if (s->num_frames == s->max_frames_per_packet || (len && len + size - 1 > s->max_payload_size)) {
  40         int header_size = s->num_frames + 1;
  41         p = s->buf + max_header_toc_size - header_size;
  42         if (p != s->buf)
  43             memmove(p, s->buf, header_size);
  44
  45         ff_rtp_send_data(s1, p, s->buf_ptr - p, 1);
  46
  47         s->num_frames = 0;
  48     }
  49
  50     if (!s->num_frames) {
  51         s->buf[0]    = 0xf0;
  52         s->buf_ptr   = s->buf + max_header_toc_size;
  53         s->timestamp = s->cur_timestamp;
  54     } else {
  55         /* Mark the previous TOC entry as having more entries following. */
  56         s->buf[1 + s->num_frames - 1] |= 0x80;
  57     }
  58
  59     /* Copy the frame type and quality bits. */
  60     s->buf[1 + s->num_frames++] = buff[0] & 0x7C;
  61     buff++;
  62     size--;
  63     memcpy(s->buf_ptr, buff, size);
  64     s->buf_ptr += size;
  65 }
  66