FFmpeg: libavformat/rtpenc_amr.c Source File

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libavformat

rtpenc_amr.c

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1 /*

2 * RTP packetization for AMR audio

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 */

23 #include "avformat.h"

24 #include "rtpenc.h"

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;

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);

45 ff_rtp_send_data(s1, p, s->buf_ptr - p, 1);

47 s->num_frames = 0;

48 }

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 }

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 }

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