tty.c
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1 /*
2  * Tele-typewriter demuxer
3  * Copyright (c) 2010 Peter Ross <pross@xvid.org>
4  *
5  * This file is part of Libav.
6  *
7  * Libav 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  * Libav 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 Libav; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
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"
36 
37 typedef struct {
38  AVClass *class;
40  uint64_t fsize;
41  char *video_size;
42  char *framerate;
44 
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;
54 
55  avio_seek(pb, start_pos, SEEK_SET);
56  if (avio_r8(pb) != 0x1A)
57  return -1;
58 
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  }
67 
68  GET_EFI_META("filename", 12)
69  GET_EFI_META("title", 36)
70 
71  s->fsize = start_pos;
72  return 0;
73 }
74 
75 static int read_header(AVFormatContext *avctx,
77 {
78  TtyDemuxContext *s = avctx->priv_data;
79  int width = 0, height = 0, ret = 0;
80  AVStream *st = avformat_new_stream(avctx, NULL);
81  AVRational framerate;
82 
83  if (!st) {
84  ret = AVERROR(ENOMEM);
85  goto fail;
86  }
87  st->codec->codec_tag = 0;
90 
91  if (s->video_size && (ret = av_parse_video_size(&width, &height, s->video_size)) < 0) {
92  av_log (avctx, AV_LOG_ERROR, "Couldn't parse video size.\n");
93  goto fail;
94  }
95  if ((ret = av_parse_video_rate(&framerate, s->framerate)) < 0) {
96  av_log(avctx, AV_LOG_ERROR, "Could not parse framerate: %s.\n", s->framerate);
97  goto fail;
98  }
99  st->codec->width = width;
100  st->codec->height = height;
101  avpriv_set_pts_info(st, 60, framerate.den, framerate.num);
102 
103  /* simulate tty display speed */
105 
106  if (avctx->pb->seekable) {
107  s->fsize = avio_size(avctx->pb);
108  st->duration = (s->fsize + s->chars_per_frame - 1) / s->chars_per_frame;
109 
110  if (ff_sauce_read(avctx, &s->fsize, 0, 0) < 0)
111  efi_read(avctx, s->fsize - 51);
112 
113  avio_seek(avctx->pb, 0, SEEK_SET);
114  }
115 
116 fail:
117  return ret;
118 }
119 
120 static int read_packet(AVFormatContext *avctx, AVPacket *pkt)
121 {
122  TtyDemuxContext *s = avctx->priv_data;
123  int n;
124 
125  if (avctx->pb->eof_reached)
126  return AVERROR_EOF;
127 
128  n = s->chars_per_frame;
129  if (s->fsize) {
130  // ignore metadata buffer
131  uint64_t p = avio_tell(avctx->pb);
132  if (p + s->chars_per_frame > s->fsize)
133  n = s->fsize - p;
134  }
135 
136  pkt->size = av_get_packet(avctx->pb, pkt, n);
137  if (pkt->size <= 0)
138  return AVERROR(EIO);
139  pkt->flags |= AV_PKT_FLAG_KEY;
140  return 0;
141 }
142 
143 #define OFFSET(x) offsetof(TtyDemuxContext, x)
144 #define DEC AV_OPT_FLAG_DECODING_PARAM
145 static const AVOption options[] = {
146  { "chars_per_frame", "", offsetof(TtyDemuxContext, chars_per_frame), AV_OPT_TYPE_INT, {.dbl = 6000}, 1, INT_MAX, AV_OPT_FLAG_DECODING_PARAM},
147  { "video_size", "A string describing frame size, such as 640x480 or hd720.", OFFSET(video_size), AV_OPT_TYPE_STRING, {.str = NULL}, 0, 0, DEC },
148  { "framerate", "", OFFSET(framerate), AV_OPT_TYPE_STRING, {.str = "25"}, 0, 0, DEC },
149  { NULL },
150 };
151 
152 static const AVClass tty_demuxer_class = {
153  .class_name = "TTY demuxer",
154  .item_name = av_default_item_name,
155  .option = options,
156  .version = LIBAVUTIL_VERSION_INT,
157 };
158 
160  .name = "tty",
161  .long_name = NULL_IF_CONFIG_SMALL("Tele-typewriter"),
162  .priv_data_size = sizeof(TtyDemuxContext),
165  .extensions = "ans,art,asc,diz,ice,nfo,txt,vt",
166  .priv_class = &tty_demuxer_class,
167 };