libavformat/tty.c

   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 "demux.h"
  35 #include "internal.h"
  36 #include "sauce.h"
  37
  38 static int isansicode(int x)
  39 {
  40     return x == 0x1B || x == 0x0A || x == 0x0D || (x >= 0x20 && x < 0x7f);
  41 }
  42
  43 static const char tty_extensions[31] = "ans,art,asc,diz,ice,nfo,txt,vt";
  44
  45 typedef struct TtyDemuxContext {
  46     AVClass *class;
  47     int chars_per_frame;
  48     uint64_t fsize;  /**< file size less metadata buffer */
  49     int width, height; /**< Set by a private option. */
  50     AVRational framerate; /**< Set by a private option. */
  51 } TtyDemuxContext;
  52
  53 static int read_probe(const AVProbeData *p)
  54 {
  55     int cnt = 0;
  56
  57     if (!p->buf_size)
  58         return 0;
  59
  60     for (int i = 0; i < 8 && i < p->buf_size; i++)
  61         cnt += !!isansicode(p->buf[i]);
  62
  63     if (cnt != 8)
  64         return 0;
  65
  66     for (int i = 8; i < p->buf_size; i++)
  67         cnt += !!isansicode(p->buf[i]);
  68
  69     return (cnt * 99LL / p->buf_size) * (cnt > 400) *
  70         !!av_match_ext(p->filename, tty_extensions);
  71 }
  72
  73 /**
  74  * Parse EFI header
  75  */
  76 static int efi_read(AVFormatContext *avctx, uint64_t start_pos)
  77 {
  78     TtyDemuxContext *s = avctx->priv_data;
  79     AVIOContext *pb = avctx->pb;
  80     char buf[37];
  81     int len;
  82
  83     avio_seek(pb, start_pos, SEEK_SET);
  84     if (avio_r8(pb) != 0x1A)
  85         return -1;
  86
  87 #define GET_EFI_META(name,size) \
  88     len = avio_r8(pb); \
  89     if (len < 1 || len > size) \
  90         return -1; \
  91     if (avio_read(pb, buf, size) == size) { \
  92         buf[len] = 0; \
  93         av_dict_set(&avctx->metadata, name, buf, 0); \
  94     }
  95
  96     GET_EFI_META("filename", 12)
  97     GET_EFI_META("title",    36)
  98
  99     s->fsize = start_pos;
 100     return 0;
 101 }
 102
 103 static int read_header(AVFormatContext *avctx)
 104 {
 105     TtyDemuxContext *s = avctx->priv_data;
 106     int ret = 0;
 107     AVStream *st = avformat_new_stream(avctx, NULL);
 108
 109     if (!st) {
 110         ret = AVERROR(ENOMEM);
 111         goto fail;
 112     }
 113     st->codecpar->codec_tag   = 0;
 114     st->codecpar->codec_type  = AVMEDIA_TYPE_VIDEO;
 115     st->codecpar->codec_id    = AV_CODEC_ID_ANSI;
 116
 117     st->codecpar->width  = s->width;
 118     st->codecpar->height = s->height;
 119     avpriv_set_pts_info(st, 60, s->framerate.den, s->framerate.num);
 120     st->avg_frame_rate = s->framerate;
 121
 122     /* simulate tty display speed */
 123     s->chars_per_frame = FFMAX(av_q2d(st->time_base)*s->chars_per_frame, 1);
 124
 125     if (avctx->pb->seekable & AVIO_SEEKABLE_NORMAL) {
 126         int64_t fsize = avio_size(avctx->pb);
 127         if (fsize > 0) {
 128             s->fsize = fsize;
 129             st->duration = (s->fsize + s->chars_per_frame - 1) / s->chars_per_frame;
 130
 131             if (ff_sauce_read(avctx, &s->fsize, 0, 0) < 0)
 132                 efi_read(avctx, s->fsize - 51);
 133
 134             avio_seek(avctx->pb, 0, SEEK_SET);
 135         }
 136     }
 137
 138 fail:
 139     return ret;
 140 }
 141
 142 static int read_packet(AVFormatContext *avctx, AVPacket *pkt)
 143 {
 144     TtyDemuxContext *s = avctx->priv_data;
 145     int n;
 146
 147     if (avio_feof(avctx->pb))
 148         return AVERROR_EOF;
 149
 150     n = s->chars_per_frame;
 151     if (s->fsize) {
 152         // ignore metadata buffer
 153         uint64_t p = avio_tell(avctx->pb);
 154         if (p == s->fsize)
 155             return AVERROR_EOF;
 156         if (p + s->chars_per_frame > s->fsize)
 157             n = s->fsize - p;
 158     }
 159
 160     pkt->size = av_get_packet(avctx->pb, pkt, n);
 161     if (pkt->size < 0)
 162         return pkt->size;
 163     pkt->stream_index = 0;
 164     pkt->pts = pkt->pos / s->chars_per_frame;
 165     pkt->flags |= AV_PKT_FLAG_KEY;
 166     return 0;
 167 }
 168
 169 #define OFFSET(x) offsetof(TtyDemuxContext, x)
 170 #define DEC AV_OPT_FLAG_DECODING_PARAM
 171 static const AVOption options[] = {
 172     { "chars_per_frame", "", offsetof(TtyDemuxContext, chars_per_frame), AV_OPT_TYPE_INT, {.i64 = 6000}, 1, INT_MAX, AV_OPT_FLAG_DECODING_PARAM},
 173     { "video_size", "A string describing frame size, such as 640x480 or hd720.", OFFSET(width), AV_OPT_TYPE_IMAGE_SIZE, {.str = NULL}, 0, 0, DEC },
 174     { "framerate", "", OFFSET(framerate), AV_OPT_TYPE_VIDEO_RATE, {.str = "25"}, 0, INT_MAX, DEC },
 175     { NULL },
 176 };
 177
 178 static const AVClass tty_demuxer_class = {
 179     .class_name     = "TTY demuxer",
 180     .item_name      = av_default_item_name,
 181     .option         = options,
 182     .version        = LIBAVUTIL_VERSION_INT,
 183 };
 184
 185 const FFInputFormat ff_tty_demuxer = {
 186     .p.name         = "tty",
 187     .p.long_name    = NULL_IF_CONFIG_SMALL("Tele-typewriter"),
 188     .p.extensions   = tty_extensions,
 189     .p.priv_class   = &tty_demuxer_class,
 190     .p.flags        = AVFMT_GENERIC_INDEX,
 191     .priv_data_size = sizeof(TtyDemuxContext),
 192     .read_probe     = read_probe,
 193     .read_header    = read_header,
 194     .read_packet    = read_packet,
 195 };