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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. }
  66.