FFmpeg: libavformat/tty.c Source File

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libavformat

tty.c

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1 /*

2 * Tele-typewriter 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 /**

23 * @file

24 * Tele-typewriter demuxer

25 */

27 #include "libavutil/intreadwrite.h"

28 #include "libavutil/avstring.h"

29 #include "libavutil/log.h"

30 #include "libavutil/dict.h"

31 #include "libavutil/opt.h"

32 #include "libavutil/parseutils.h"

33 #include "avformat.h"

34 #include "internal.h"

35 #include "sauce.h"

37 typedef struct TtyDemuxContext {

38 AVClass *class;

39 int chars_per_frame;

40 uint64_t fsize; /**< file size less metadata buffer */

41 int width, height; /**< Set by a private option. */

42 AVRational framerate; /**< Set by a private option. */

43 } TtyDemuxContext;

45 /**

46 * Parse EFI header

47 */

48 static int efi_read(AVFormatContext *avctx, uint64_t start_pos)

49 {

50 TtyDemuxContext *s = avctx->priv_data;

51 AVIOContext *pb = avctx->pb;

52 char buf[37];

53 int len;

55 avio_seek(pb, start_pos, SEEK_SET);

56 if (avio_r8(pb) != 0x1A)

57 return -1;

59 #define GET_EFI_META(name,size) \

60 len = avio_r8(pb); \

61 if (len < 1 || len > size) \

62 return -1; \

63 if (avio_read(pb, buf, size) == size) { \

64 buf[len] = 0; \

65 av_dict_set(&avctx->metadata, name, buf, 0); \

66 }

68 GET_EFI_META("filename", 12)

69 GET_EFI_META("title", 36)

71 s->fsize = start_pos;

72 return 0;

73 }

75 static int read_header(AVFormatContext *avctx)

76 {

77 TtyDemuxContext *s = avctx->priv_data;

78 int ret = 0;

79 AVStream *st = avformat_new_stream(avctx, NULL);

81 if (!st) {

82 ret = AVERROR(ENOMEM);

83 goto fail;

84 }

85 st->codec->codec_tag = 0;

86 st->codec->codec_type = AVMEDIA_TYPE_VIDEO;

87 st->codec->codec_id = AV_CODEC_ID_ANSI;

89 st->codec->width = s->width;

90 st->codec->height = s->height;

91 avpriv_set_pts_info(st, 60, s->framerate.den, s->framerate.num);

92 st->avg_frame_rate = s->framerate;

94 /* simulate tty display speed */

95 s->chars_per_frame = FFMAX(av_q2d(st->time_base)*s->chars_per_frame, 1);

97 if (avctx->pb->seekable) {

98 s->fsize = avio_size(avctx->pb);

99 st->duration = (s->fsize + s->chars_per_frame - 1) / s->chars_per_frame;

100

101 if (ff_sauce_read(avctx, &s->fsize, 0, 0) < 0)

102 efi_read(avctx, s->fsize - 51);

103

104 avio_seek(avctx->pb, 0, SEEK_SET);

105 }

106

107 fail:

108 return ret;

109 }

110

111 static int read_packet(AVFormatContext *avctx, AVPacket *pkt)

112 {

113 TtyDemuxContext *s = avctx->priv_data;

114 int n;

115

116 if (avio_feof(avctx->pb))

117 return AVERROR_EOF;

118

119 n = s->chars_per_frame;

120 if (s->fsize) {

121 // ignore metadata buffer

122 uint64_t p = avio_tell(avctx->pb);

123 if (p == s->fsize)

124 return AVERROR_EOF;

125 if (p + s->chars_per_frame > s->fsize)

126 n = s->fsize - p;

127 }

128

129 pkt->size = av_get_packet(avctx->pb, pkt, n);

130 if (pkt->size < 0)

131 return pkt->size;

132 pkt->flags |= AV_PKT_FLAG_KEY;

133 return 0;

134 }

135

136 #define OFFSET(x) offsetof(TtyDemuxContext, x)

137 #define DEC AV_OPT_FLAG_DECODING_PARAM

138 static const AVOption options[] = {

139 { "chars_per_frame", "", offsetof(TtyDemuxContext, chars_per_frame), AV_OPT_TYPE_INT, {.i64 = 6000}, 1, INT_MAX, AV_OPT_FLAG_DECODING_PARAM},

140 { "video_size", "A string describing frame size, such as 640x480 or hd720.", OFFSET(width), AV_OPT_TYPE_IMAGE_SIZE, {.str = NULL}, 0, 0, DEC },

141 { "framerate", "", OFFSET(framerate), AV_OPT_TYPE_VIDEO_RATE, {.str = "25"}, 0, 0, DEC },

142 { NULL },

143 };

144

145 static const AVClass tty_demuxer_class = {

146 .class_name = "TTY demuxer",

147 .item_name = av_default_item_name,

148 .option = options,

149 .version = LIBAVUTIL_VERSION_INT,

150 };

151

152 AVInputFormat ff_tty_demuxer = {

153 .name = "tty",

154 .long_name = NULL_IF_CONFIG_SMALL("Tele-typewriter"),

155 .priv_data_size = sizeof(TtyDemuxContext),

156 .read_header = read_header,

157 .read_packet = read_packet,

158 .extensions = "ans,art,asc,diz,ice,nfo,txt,vt",

159 .priv_class = &tty_demuxer_class,

160 };

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