FFmpeg: libavformat/assdec.c Source File

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libavformat

assdec.c

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1 /*

2 * SSA/ASS 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 "libavcodec/internal.h"

26 #include "libavutil/bprint.h"

28 typedef struct ASSContext{

29 FFDemuxSubtitlesQueue q;

30 }ASSContext;

32 static int ass_probe(AVProbeData *p)

33 {

34 const char *header= "[Script Info]";

36 if( !memcmp(p->buf , header, strlen(header))

37 || !memcmp(p->buf+3, header, strlen(header)))

38 return AVPROBE_SCORE_MAX;

40 return 0;

41 }

43 static int ass_read_close(AVFormatContext *s)

44 {

45 ASSContext *ass = s->priv_data;

46 ff_subtitles_queue_clean(&ass->q);

47 return 0;

48 }

50 static int read_ts(const uint8_t *p, int64_t *start, int *duration)

51 {

52 int64_t end;

53 int hh1, mm1, ss1, ms1;

54 int hh2, mm2, ss2, ms2;

56 if (sscanf(p, "%*[^,],%d:%d:%d%*c%d,%d:%d:%d%*c%d",

57 &hh1, &mm1, &ss1, &ms1,

58 &hh2, &mm2, &ss2, &ms2) == 8) {

59 end = (hh2*3600LL + mm2*60LL + ss2) * 100LL + ms2;

60 *start = (hh1*3600LL + mm1*60LL + ss1) * 100LL + ms1;

61 *duration = end - *start;

62 return 0;

63 }

64 return -1;

65 }

67 static int64_t get_line(AVBPrint *buf, AVIOContext *pb)

68 {

69 int64_t pos = avio_tell(pb);

71 av_bprint_clear(buf);

72 for (;;) {

73 char c = avio_r8(pb);

74 if (!c)

75 break;

76 av_bprint_chars(buf, c, 1);

77 if (c == '\n')

78 break;

79 }

80 return pos;

81 }

83 static int ass_read_header(AVFormatContext *s)

84 {

85 ASSContext *ass = s->priv_data;

86 AVBPrint header, line;

87 int header_remaining, res = 0;

88 AVStream *st;

90 st = avformat_new_stream(s, NULL);

91 if (!st)

92 return AVERROR(ENOMEM);

93 avpriv_set_pts_info(st, 64, 1, 100);

94 st->codec->codec_type = AVMEDIA_TYPE_SUBTITLE;

95 st->codec->codec_id= AV_CODEC_ID_SSA;

97 header_remaining= INT_MAX;

99 av_bprint_init(&header, 0, AV_BPRINT_SIZE_UNLIMITED);

100 av_bprint_init(&line, 0, AV_BPRINT_SIZE_UNLIMITED);

101

102 for (;;) {

103 int64_t pos = get_line(&line, s->pb);

104

105 if (!line.str[0]) // EOF

106 break;

107

108 if (!memcmp(line.str, "[Events]", 8))

109 header_remaining= 2;

110 else if (line.str[0]=='[')

111 header_remaining= INT_MAX;

112

113 if (header_remaining) {

114 av_bprintf(&header, "%s", line.str);

115 header_remaining--;

116 } else {

117 int64_t ts_start = AV_NOPTS_VALUE;

118 int duration = -1;

119 AVPacket *sub;

120

121 if (read_ts(line.str, &ts_start, &duration) < 0)

122 continue;

123 sub = ff_subtitles_queue_insert(&ass->q, line.str, line.len, 0);

124 if (!sub) {

125 res = AVERROR(ENOMEM);

126 goto end;

127 }

128 sub->pos = pos;

129 sub->pts = ts_start;

130 sub->duration = duration;

131 }

132 }

133

134 av_bprint_finalize(&line, NULL);

135

136 res = avpriv_bprint_to_extradata(st->codec, &header);

137 if (res < 0)

138 goto end;

139

140 ff_subtitles_queue_finalize(&ass->q);

141

142 end:

143 return res;

144 }

145

146 static int ass_read_packet(AVFormatContext *s, AVPacket *pkt)

147 {

148 ASSContext *ass = s->priv_data;

149 return ff_subtitles_queue_read_packet(&ass->q, pkt);

150 }

151

152 static int ass_read_seek(AVFormatContext *s, int stream_index,

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

154 {

155 ASSContext *ass = s->priv_data;

156 return ff_subtitles_queue_seek(&ass->q, s, stream_index,

157 min_ts, ts, max_ts, flags);

158 }

159

160 AVInputFormat ff_ass_demuxer = {

161 .name = "ass",

162 .long_name = NULL_IF_CONFIG_SMALL("SSA (SubStation Alpha) subtitle"),

163 .priv_data_size = sizeof(ASSContext),

164 .read_probe = ass_probe,

165 .read_header = ass_read_header,

166 .read_packet = ass_read_packet,

167 .read_close = ass_read_close,

168 .read_seek2 = ass_read_seek,

169 };

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