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/libavformat/rtpenc_amr.c

http://github.com/FFmpeg/FFmpeg
C | 70 lines | 35 code | 7 blank | 28 comment | 6 complexity | bb95f315ca56e829df71e701926d7e5f MD5 | raw file
 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 */
30void ff_rtp_send_amr(AVFormatContext *s1, const uint8_t *buff, int size)
31{
32    RTPMuxContext *s          = s1->priv_data;
33    AVStream *st              = s1->streams[0];
34    int max_header_toc_size   = 1 + s->max_frames_per_packet;
35    uint8_t *p;
36    int len;
37
38    /* Test if the packet must be sent. */
39    len = s->buf_ptr - s->buf;
40    if (s->num_frames &&
41        (s->num_frames == s->max_frames_per_packet ||
42         len + size - 1 > s->max_payload_size ||
43         av_compare_ts(s->cur_timestamp - s->timestamp, st->time_base,
44                       s1->max_delay, AV_TIME_BASE_Q) >= 0)) {
45        int header_size = s->num_frames + 1;
46        p = s->buf + max_header_toc_size - header_size;
47        if (p != s->buf)
48            memmove(p, s->buf, header_size);
49
50        ff_rtp_send_data(s1, p, s->buf_ptr - p, 1);
51
52        s->num_frames = 0;
53    }
54
55    if (!s->num_frames) {
56        s->buf[0]    = 0xf0;
57        s->buf_ptr   = s->buf + max_header_toc_size;
58        s->timestamp = s->cur_timestamp;
59    } else {
60        /* Mark the previous TOC entry as having more entries following. */
61        s->buf[1 + s->num_frames - 1] |= 0x80;
62    }
63
64    /* Copy the frame type and quality bits. */
65    s->buf[1 + s->num_frames++] = buff[0] & 0x7C;
66    buff++;
67    size--;
68    memcpy(s->buf_ptr, buff, size);
69    s->buf_ptr += size;
70}