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rtpenc_amr.c
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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 }