FFmpeg: libavformat/srtenc.c Source File

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libavformat

srtenc.c

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1 /*

2 * SubRip subtitle muxer

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 "avformat.h"

23 #include "internal.h"

24 #include "libavutil/log.h"

25 #include "libavutil/intreadwrite.h"

27 /* TODO: add options for:

28 - character encoding;

29 - LF / CRLF;

30 - byte order mark.

31 */

33 typedef struct SRTContext{

34 unsigned index;

35 } SRTContext;

37 static int srt_write_header(AVFormatContext *avf)

38 {

39 SRTContext *srt = avf->priv_data;

41 if (avf->nb_streams != 1 ||

42 avf->streams[0]->codec->codec_type != AVMEDIA_TYPE_SUBTITLE) {

43 av_log(avf, AV_LOG_ERROR,

44 "SRT supports only a single subtitles stream.\n");

45 return AVERROR(EINVAL);

46 }

47 if (avf->streams[0]->codec->codec_id != AV_CODEC_ID_TEXT &&

48 avf->streams[0]->codec->codec_id != AV_CODEC_ID_SUBRIP &&

49 avf->streams[0]->codec->codec_id != AV_CODEC_ID_SRT) {

50 av_log(avf, AV_LOG_ERROR,

51 "Unsupported subtitles codec: %s\n",

52 avcodec_get_name(avf->streams[0]->codec->codec_id));

53 return AVERROR(EINVAL);

54 }

55 avpriv_set_pts_info(avf->streams[0], 64, 1, 1000);

56 srt->index = 1;

57 return 0;

58 }

60 static int srt_write_packet(AVFormatContext *avf, AVPacket *pkt)

61 {

62 SRTContext *srt = avf->priv_data;

63 int write_ts = avf->streams[0]->codec->codec_id != AV_CODEC_ID_SRT;

65 if (write_ts) {

66 int64_t s = pkt->pts, e, d = pkt->duration;

67 int size, x1 = -1, y1 = -1, x2 = -1, y2 = -1;

68 const uint8_t *p;

70 p = av_packet_get_side_data(pkt, AV_PKT_DATA_SUBTITLE_POSITION, &size);

71 if (p && size == 16) {

72 x1 = AV_RL32(p );

73 y1 = AV_RL32(p + 4);

74 x2 = AV_RL32(p + 8);

75 y2 = AV_RL32(p + 12);

76 }

78 if (d <= 0)

79 /* For backward compatibility, fallback to convergence_duration. */

80 d = pkt->convergence_duration;

81 if (s == AV_NOPTS_VALUE || d < 0) {

82 av_log(avf, AV_LOG_WARNING,

83 "Insufficient timestamps in event number %d.\n", srt->index);

84 return 0;

85 }

86 e = s + d;

87 avio_printf(avf->pb, "%d\n%02d:%02d:%02d,%03d --> %02d:%02d:%02d,%03d",

88 srt->index,

89 (int)(s / 3600000), (int)(s / 60000) % 60,

90 (int)(s / 1000) % 60, (int)(s % 1000),

91 (int)(e / 3600000), (int)(e / 60000) % 60,

92 (int)(e / 1000) % 60, (int)(e % 1000));

93 if (p)

94 avio_printf(avf->pb, " X1:%03d X2:%03d Y1:%03d Y2:%03d",

95 x1, x2, y1, y2);

96 avio_printf(avf->pb, "\n");

97 }

98 avio_write(avf->pb, pkt->data, pkt->size);

99 if (write_ts)

100 avio_write(avf->pb, "\n\n", 2);

101 srt->index++;

102 return 0;

103 }

104

105 AVOutputFormat ff_srt_muxer = {

106 .name = "srt",

107 .long_name = NULL_IF_CONFIG_SMALL("SubRip subtitle"),

108 .mime_type = "application/x-subrip",

109 .extensions = "srt",

110 .priv_data_size = sizeof(SRTContext),

111 .write_header = srt_write_header,

112 .write_packet = srt_write_packet,

113 .flags = AVFMT_VARIABLE_FPS | AVFMT_TS_NONSTRICT,

114 .subtitle_codec = AV_CODEC_ID_SUBRIP,

115 };

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