FFmpeg: libavformat/rtpenc_xiph.c Source File

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libavformat

rtpenc_xiph.c

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1 /*

2 * RTP packetization for Xiph audio and video

4 *

5 * This file is part of FFmpeg.

6 *

7 * FFmpeg is free software; you can redistribute it and/or

8 * modify it under the terms of the GNU Lesser General Public

9 * License as published by the Free Software Foundation; either

10 * version 2.1 of the License, or (at your option) any later version.

11 *

12 * FFmpeg is distributed in the hope that it will be useful,

13 * but WITHOUT ANY WARRANTY; without even the implied warranty of

14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU

15 * Lesser General Public License for more details.

16 *

17 * You should have received a copy of the GNU Lesser General Public

18 * License along with FFmpeg; if not, write to the Free Software

19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

20 */

22 #include "libavutil/avassert.h"

23 #include "avformat.h"

24 #include "rtpenc.h"

26 /**

27 * Packetize Xiph frames into RTP according to

28 * RFC 5215 (Vorbis) and the Theora RFC draft.

29 * (http://svn.xiph.org/trunk/theora/doc/draft-ietf-avt-rtp-theora-00.txt)

30 */

31 void ff_rtp_send_xiph(AVFormatContext *s1, const uint8_t *buff, int size)

32 {

33 RTPMuxContext *s = s1->priv_data;

34 int max_pkt_size, xdt, frag;

35 uint8_t *q;

37 max_pkt_size = s->max_payload_size;

39 // set xiph data type

40 switch (*buff) {

41 case 0x01: // vorbis id

42 case 0x05: // vorbis setup

43 case 0x80: // theora header

44 case 0x82: // theora tables

45 xdt = 1; // packed config payload

46 break;

47 case 0x03: // vorbis comments

48 case 0x81: // theora comments

49 xdt = 2; // comment payload

50 break;

51 default:

52 xdt = 0; // raw data payload

53 break;

54 }

56 // Set ident.

57 // Probably need a non-fixed way of generating

58 // this, but it has to be done in SDP and passed in from there.

59 q = s->buf;

60 *q++ = (RTP_XIPH_IDENT >> 16) & 0xff;

61 *q++ = (RTP_XIPH_IDENT >> 8) & 0xff;

62 *q++ = (RTP_XIPH_IDENT ) & 0xff;

64 // set fragment

65 // 0 - whole frame (possibly multiple frames)

66 // 1 - first fragment

67 // 2 - fragment continuation

68 // 3 - last fragmement

69 frag = size <= max_pkt_size ? 0 : 1;

71 if (!frag && !xdt) { // do we have a whole frame of raw data?

72 uint8_t *end_ptr = s->buf + 6 + max_pkt_size; // what we're allowed to write

73 uint8_t *ptr = s->buf_ptr + 2 + size; // what we're going to write

74 int remaining = end_ptr - ptr;

76 av_assert1(s->num_frames <= s->max_frames_per_packet);

77 if ((s->num_frames > 0 && remaining < 0) ||

78 s->num_frames == s->max_frames_per_packet) {

79 // send previous packets now; no room for new data

80 ff_rtp_send_data(s1, s->buf, s->buf_ptr - s->buf, 0);

81 s->num_frames = 0;

82 }

84 // buffer current frame to send later

85 if (0 == s->num_frames) s->timestamp = s->cur_timestamp;

86 s->num_frames++;

88 // Set packet header. Normally, this is OR'd with frag and xdt,

89 // but those are zero, so omitted here

90 *q++ = s->num_frames;

92 if (s->num_frames > 1) q = s->buf_ptr; // jump ahead if needed

93 *q++ = (size >> 8) & 0xff;

94 *q++ = size & 0xff;

95 memcpy(q, buff, size);

96 q += size;

97 s->buf_ptr = q;

99 return;

100 } else if (s->num_frames) {

101 // immediately send buffered frames if buffer is not raw data,

102 // or if current frame is fragmented.

103 ff_rtp_send_data(s1, s->buf, s->buf_ptr - s->buf, 0);

104 }

105

106 s->timestamp = s->cur_timestamp;

107 s->num_frames = 0;

108 s->buf_ptr = q;

109 while (size > 0) {

110 int len = (!frag || frag == 3) ? size : max_pkt_size;

111 q = s->buf_ptr;

112

113 // set packet headers

114 *q++ = (frag << 6) | (xdt << 4); // num_frames = 0

115 *q++ = (len >> 8) & 0xff;

116 *q++ = len & 0xff;

117 // set packet body

118 memcpy(q, buff, len);

119 q += len;

120 buff += len;

121 size -= len;

122

123 ff_rtp_send_data(s1, s->buf, q - s->buf, 0);

124

125 frag = size <= max_pkt_size ? 3 : 2;

126 }

127 }

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