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 "libavutil/intreadwrite.h"

25 #include "avformat.h"

26 #include "rtpenc.h"

28 /**

29 * Packetize Xiph frames into RTP according to

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

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

32 */

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

34 {

35 RTPMuxContext *s = s1->priv_data;

36 AVStream *st = s1->streams[0];

37 int max_pkt_size, xdt, frag;

38 uint8_t *q;

40 max_pkt_size = s->max_payload_size - 6; // ident+frag+tdt/vdt+pkt_num+pkt_length

42 // set xiph data type

43 switch (*buff) {

44 case 0x01: // vorbis id

45 case 0x05: // vorbis setup

46 case 0x80: // theora header

47 case 0x82: // theora tables

48 xdt = 1; // packed config payload

49 break;

50 case 0x03: // vorbis comments

51 case 0x81: // theora comments

52 xdt = 2; // comment payload

53 break;

54 default:

55 xdt = 0; // raw data payload

56 break;

57 }

59 // Set ident.

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

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

62 q = s->buf;

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

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

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

67 // set fragment

68 // 0 - whole frame (possibly multiple frames)

69 // 1 - first fragment

70 // 2 - fragment continuation

71 // 3 - last fragmement

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

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

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

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

77 int remaining = end_ptr - ptr;

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

80 if (s->num_frames > 0 &&

81 (remaining < 0 ||

82 s->num_frames == s->max_frames_per_packet ||

83 av_compare_ts(s->cur_timestamp - s->timestamp, st->time_base,

84 s1->max_delay, AV_TIME_BASE_Q) >= 0)) {

85 // send previous packets now; no room for new data, or too much delay

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

87 s->num_frames = 0;

88 }

90 // buffer current frame to send later

91 if (0 == s->num_frames)

92 s->timestamp = s->cur_timestamp;

93 s->num_frames++;

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

96 // but those are zero, so omitted here

97 *q++ = s->num_frames;

99 if (s->num_frames > 1)

100 q = s->buf_ptr; // jump ahead if needed

101 AV_WB16(q, size);

102 q += 2;

103 memcpy(q, buff, size);

104 q += size;

105 s->buf_ptr = q;

106

107 return;

108 } else if (s->num_frames) {

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

110 // or if current frame is fragmented.

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

112 }

113

114 s->timestamp = s->cur_timestamp;

115 s->num_frames = 0;

116 s->buf_ptr = q;

117 while (size > 0) {

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

119 q = s->buf_ptr;

120

121 // set packet headers

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

123 AV_WB16(q, len);

124 q += 2;

125 // set packet body

126 memcpy(q, buff, len);

127 q += len;

128 buff += len;

129 size -= len;

130

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

132

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

134 }

135 }

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