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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 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  */
21 
22 /**
23  * @file
24  * Tele-typewriter demuxer
25  */
26 
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; /**< file size less metadata buffer */
41  int width, height; /**< Set by a private option. */
42  AVRational framerate; /**< Set by a private option. */
44 
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;
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)
76 {
77  TtyDemuxContext *s = avctx->priv_data;
78  int ret = 0;
79  AVStream *st = avformat_new_stream(avctx, NULL);
80 
81  if (!st) {
82  ret = AVERROR(ENOMEM);
83  goto fail;
84  }
85  st->codec->codec_tag = 0;
88 
89  st->codec->width = s->width;
90  st->codec->height = s->height;
92  st->avg_frame_rate = s->framerate;
93 
94  /* simulate tty display speed */
96 
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 
112 {
113  TtyDemuxContext *s = avctx->priv_data;
114  int n;
115 
116  if (url_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 
153  .name = "tty",
154  .long_name = NULL_IF_CONFIG_SMALL("Tele-typewriter"),
155  .priv_data_size = sizeof(TtyDemuxContext),
158  .extensions = "ans,art,asc,diz,ice,nfo,txt,vt",
159  .priv_class = &tty_demuxer_class,
160 };