libavformat/sccdec.c

   1 /*
   2  * SCC subtitle demuxer
   3  * Copyright (c) 2017 Paul B Mahol
   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 #include "avformat.h"
  23 #include "internal.h"
  24 #include "subtitles.h"
  25 #include "libavutil/avstring.h"
  26 #include "libavutil/bprint.h"
  27 #include "libavutil/intreadwrite.h"
  28
  29 typedef struct SCCContext {
  30     FFDemuxSubtitlesQueue q;
  31 } SCCContext;
  32
  33 static int scc_probe(const AVProbeData *p)
  34 {
  35     char buf[18];
  36     FFTextReader tr;
  37
  38     ff_text_init_buf(&tr, p->buf, p->buf_size);
  39
  40     while (ff_text_peek_r8(&tr) == '\r' || ff_text_peek_r8(&tr) == '\n')
  41         ff_text_r8(&tr);
  42
  43     ff_text_read(&tr, buf, sizeof(buf));
  44
  45     if (!memcmp(buf, "Scenarist_SCC V1.0", 18))
  46         return AVPROBE_SCORE_MAX;
  47
  48     return 0;
  49 }
  50
  51 static int convert(uint8_t x)
  52 {
  53     if (x >= 'a')
  54         x -= 87;
  55     else if (x >= 'A')
  56         x -= 55;
  57     else
  58         x -= '0';
  59     return x;
  60 }
  61
  62 static int scc_read_header(AVFormatContext *s)
  63 {
  64     SCCContext *scc = s->priv_data;
  65     AVStream *st = avformat_new_stream(s, NULL);
  66     char line[4096], line2[4096];
  67     int64_t ts_start, ts_end;
  68     int count = 0, ret = 0;
  69     ptrdiff_t len2, len;
  70     uint8_t out[4096];
  71     FFTextReader tr;
  72
  73     ff_text_init_avio(s, &tr, s->pb);
  74
  75     if (!st)
  76         return AVERROR(ENOMEM);
  77     avpriv_set_pts_info(st, 64, 1, 1000);
  78     st->codecpar->codec_type = AVMEDIA_TYPE_SUBTITLE;
  79     st->codecpar->codec_id   = AV_CODEC_ID_EIA_608;
  80
  81     while (!ff_text_eof(&tr)) {
  82         int64_t current_pos, next_pos;
  83         char *saveptr = NULL, *lline;
  84         int hh1, mm1, ss1, fs1, i;
  85         int hh2, mm2, ss2, fs2;
  86         AVPacket *sub;
  87
  88         if (count == 0) {
  89             current_pos = ff_text_pos(&tr);
  90             while (!ff_text_eof(&tr)) {
  91                 len = ff_subtitles_read_line(&tr, line, sizeof(line));
  92                 if (len > 13)
  93                     break;
  94             }
  95         }
  96
  97         if (!strncmp(line, "Scenarist_SCC V1.0", 18))
  98             continue;
  99         if (av_sscanf(line, "%d:%d:%d%*[:;]%d", &hh1, &mm1, &ss1, &fs1) != 4)
 100             continue;
 101
 102         ts_start = (hh1 * 3600LL + mm1 * 60LL + ss1) * 1000LL + fs1 * 33;
 103
 104         next_pos = ff_text_pos(&tr);
 105         while (!ff_text_eof(&tr)) {
 106             len2 = ff_subtitles_read_line(&tr, line2, sizeof(line2));
 107             if (len2 > 13)
 108                 break;
 109         }
 110         if (av_sscanf(line2, "%d:%d:%d%*[:;]%d", &hh2, &mm2, &ss2, &fs2) != 4)
 111             continue;
 112
 113         ts_end = (hh2 * 3600LL + mm2 * 60LL + ss2) * 1000LL + fs2 * 33;
 114         count++;
 115
 116 try_again:
 117         lline = (char *)&line;
 118         lline += 12;
 119
 120         for (i = 0; i < 4095; i += 3) {
 121             char *ptr = av_strtok(lline, " ", &saveptr);
 122             char c1, c2, c3, c4;
 123
 124             if (!ptr)
 125                 break;
 126
 127             if (av_sscanf(ptr, "%c%c%c%c", &c1, &c2, &c3, &c4) != 4)
 128                 break;
 129
 130             lline = NULL;
 131             out[i+0] = 0xfc;
 132             out[i+1] = convert(c2) | (convert(c1) << 4);
 133             out[i+2] = convert(c4) | (convert(c3) << 4);
 134         }
 135         out[i] = 0;
 136
 137         sub = ff_subtitles_queue_insert(&scc->q, out, i, 0);
 138         if (!sub)
 139             goto fail;
 140
 141         sub->pos = current_pos;
 142         sub->pts = ts_start;
 143         sub->duration = ts_end - ts_start;
 144         memmove(line, line2, sizeof(line));
 145         current_pos = next_pos;
 146         line2[0] = 0;
 147     }
 148
 149     if (line[0]) {
 150         ts_start = ts_end;
 151         ts_end += 1200;
 152         goto try_again;
 153     }
 154
 155     ff_subtitles_queue_finalize(s, &scc->q);
 156
 157     return ret;
 158 fail:
 159     ff_subtitles_queue_clean(&scc->q);
 160     return AVERROR(ENOMEM);
 161 }
 162
 163 static int scc_read_packet(AVFormatContext *s, AVPacket *pkt)
 164 {
 165     SCCContext *scc = s->priv_data;
 166     return ff_subtitles_queue_read_packet(&scc->q, pkt);
 167 }
 168
 169 static int scc_read_seek(AVFormatContext *s, int stream_index,
 170                          int64_t min_ts, int64_t ts, int64_t max_ts, int flags)
 171 {
 172     SCCContext *scc = s->priv_data;
 173     return ff_subtitles_queue_seek(&scc->q, s, stream_index,
 174                                    min_ts, ts, max_ts, flags);
 175 }
 176
 177 static int scc_read_close(AVFormatContext *s)
 178 {
 179     SCCContext *scc = s->priv_data;
 180     ff_subtitles_queue_clean(&scc->q);
 181     return 0;
 182 }
 183
 184 AVInputFormat ff_scc_demuxer = {
 185     .name           = "scc",
 186     .long_name      = NULL_IF_CONFIG_SMALL("Scenarist Closed Captions"),
 187     .priv_data_size = sizeof(SCCContext),
 188     .read_probe     = scc_probe,
 189     .read_header    = scc_read_header,
 190     .read_packet    = scc_read_packet,
 191     .read_seek2     = scc_read_seek,
 192     .read_close     = scc_read_close,
 193     .extensions     = "scc",
 194 };