FFmpeg: libavformat/srtdec.c Source File

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libavformat

srtdec.c

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1 /*

2 * SubRip subtitle demuxer

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 "subtitles.h"

25 #include "libavutil/bprint.h"

26 #include "libavutil/intreadwrite.h"

28 typedef struct {

29 FFDemuxSubtitlesQueue q;

30 } SRTContext;

32 static int srt_probe(AVProbeData *p)

33 {

34 const unsigned char *ptr = p->buf;

35 int i, v, num = 0;

37 if (AV_RB24(ptr) == 0xEFBBBF)

38 ptr += 3; /* skip UTF-8 BOM */

40 for (i=0; i<2; i++) {

41 if ((num == i || num + 1 == i)

42 && sscanf(ptr, "%*d:%*2d:%*2d%*1[,.]%*3d --> %*d:%*2d:%*2d%*1[,.]%3d", &v) == 1)

43 return AVPROBE_SCORE_MAX;

44 num = atoi(ptr);

45 ptr += strcspn(ptr, "\n") + 1;

46 }

47 return 0;

48 }

50 static int64_t get_pts(const char **buf, int *duration,

51 int32_t *x1, int32_t *y1, int32_t *x2, int32_t *y2)

52 {

53 int i;

55 for (i=0; i<2; i++) {

56 int hh1, mm1, ss1, ms1;

57 int hh2, mm2, ss2, ms2;

58 if (sscanf(*buf, "%d:%2d:%2d%*1[,.]%3d --> %d:%2d:%2d%*1[,.]%3d"

59 "%*[ ]X1:%u X2:%u Y1:%u Y2:%u",

60 &hh1, &mm1, &ss1, &ms1,

61 &hh2, &mm2, &ss2, &ms2,

62 x1, x2, y1, y2) >= 8) {

63 int64_t start = (hh1*3600LL + mm1*60LL + ss1) * 1000LL + ms1;

64 int64_t end = (hh2*3600LL + mm2*60LL + ss2) * 1000LL + ms2;

65 *duration = end - start;

66 *buf += strcspn(*buf, "\n");

67 *buf += !!**buf;

68 return start;

69 }

70 *buf += strcspn(*buf, "\n");

71 *buf += !!**buf;

72 }

73 return AV_NOPTS_VALUE;

74 }

76 static int srt_read_header(AVFormatContext *s)

77 {

78 SRTContext *srt = s->priv_data;

79 AVBPrint buf;

80 AVStream *st = avformat_new_stream(s, NULL);

81 int res = 0;

83 if (!st)

84 return AVERROR(ENOMEM);

85 avpriv_set_pts_info(st, 64, 1, 1000);

86 st->codec->codec_type = AVMEDIA_TYPE_SUBTITLE;

87 st->codec->codec_id = AV_CODEC_ID_SUBRIP;

89 av_bprint_init(&buf, 0, AV_BPRINT_SIZE_UNLIMITED);

91 while (!url_feof(s->pb)) {

92 ff_subtitles_read_chunk(s->pb, &buf);

94 if (buf.len) {

95 int64_t pos = avio_tell(s->pb);

96 int64_t pts;

97 int duration;

98 const char *ptr = buf.str;

99 int32_t x1 = -1, y1 = -1, x2 = -1, y2 = -1;

100 AVPacket *sub;

101

102 pts = get_pts(&ptr, &duration, &x1, &y1, &x2, &y2);

103 if (pts != AV_NOPTS_VALUE) {

104 int len = buf.len - (ptr - buf.str);

105 if (len <= 0)

106 continue;

107 sub = ff_subtitles_queue_insert(&srt->q, ptr, len, 0);

108 if (!sub) {

109 res = AVERROR(ENOMEM);

110 goto end;

111 }

112 sub->pos = pos;

113 sub->pts = pts;

114 sub->duration = duration;

115 if (x1 != -1) {

116 uint8_t *p = av_packet_new_side_data(sub, AV_PKT_DATA_SUBTITLE_POSITION, 16);

117 if (p) {

118 AV_WL32(p, x1);

119 AV_WL32(p + 4, y1);

120 AV_WL32(p + 8, x2);

121 AV_WL32(p + 12, y2);

122 }

123 }

124 }

125 }

126 }

127

128 ff_subtitles_queue_finalize(&srt->q);

129

130 end:

131 av_bprint_finalize(&buf, NULL);

132 return res;

133 }

134

135 static int srt_read_packet(AVFormatContext *s, AVPacket *pkt)

136 {

137 SRTContext *srt = s->priv_data;

138 return ff_subtitles_queue_read_packet(&srt->q, pkt);

139 }

140

141 static int srt_read_seek(AVFormatContext *s, int stream_index,

142 int64_t min_ts, int64_t ts, int64_t max_ts, int flags)

143 {

144 SRTContext *srt = s->priv_data;

145 return ff_subtitles_queue_seek(&srt->q, s, stream_index,

146 min_ts, ts, max_ts, flags);

147 }

148

149 static int srt_read_close(AVFormatContext *s)

150 {

151 SRTContext *srt = s->priv_data;

152 ff_subtitles_queue_clean(&srt->q);

153 return 0;

154 }

155

156 AVInputFormat ff_srt_demuxer = {

157 .name = "srt",

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

159 .priv_data_size = sizeof(SRTContext),

160 .read_probe = srt_probe,

161 .read_header = srt_read_header,

162 .read_packet = srt_read_packet,

163 .read_seek2 = srt_read_seek,

164 .read_close = srt_read_close,

165 };

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