libavformat/assdec.c

   1 /*
   2  * SSA/ASS demuxer
   3  * Copyright (c) 2008 Michael Niedermayer
   4  * Copyright (c) 2014 Clément Bœsch
   5  *
   6  * This file is part of FFmpeg.
   7  *
   8  * FFmpeg is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; either
  11  * version 2.1 of the License, or (at your option) any later version.
  12  *
  13  * FFmpeg is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with FFmpeg; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21  */
  22
  23 #include <stdint.h>
  24
  25 #include "avformat.h"
  26 #include "demux.h"
  27 #include "internal.h"
  28 #include "subtitles.h"
  29 #include "libavutil/bprint.h"
  30
  31 typedef struct ASSContext {
  32     FFDemuxSubtitlesQueue q;
  33     unsigned readorder;
  34 } ASSContext;
  35
  36 static int ass_probe(const AVProbeData *p)
  37 {
  38     char buf[13];
  39     FFTextReader tr;
  40     ff_text_init_buf(&tr, p->buf, p->buf_size);
  41
  42     while (ff_text_peek_r8(&tr) == '\r' || ff_text_peek_r8(&tr) == '\n')
  43         ff_text_r8(&tr);
  44
  45     ff_text_read(&tr, buf, sizeof(buf));
  46
  47     if (!memcmp(buf, "[Script Info]", 13))
  48         return AVPROBE_SCORE_MAX;
  49
  50     return 0;
  51 }
  52
  53 static int read_dialogue(ASSContext *ass, AVBPrint *dst, const uint8_t *p,
  54                          int64_t *start, int *duration)
  55 {
  56     int pos = 0;
  57     int64_t end;
  58     int hh1, mm1, ss1, ms1;
  59     int hh2, mm2, ss2, ms2;
  60
  61     if (sscanf(p, "Dialogue: %*[^,],%d:%d:%d%*c%d,%d:%d:%d%*c%d,%n",
  62                &hh1, &mm1, &ss1, &ms1,
  63                &hh2, &mm2, &ss2, &ms2, &pos) >= 8 && pos > 0) {
  64
  65         /* This is not part of the sscanf itself in order to handle an actual
  66          * number (which would be the Layer) or the form "Marked=N" (which is
  67          * the old SSA field, now replaced by Layer, and will lead to Layer
  68          * being 0 here). */
  69         const int layer = atoi(p + 10);
  70
  71         end    = (hh2*3600LL + mm2*60LL + ss2) * 100LL + ms2;
  72         *start = (hh1*3600LL + mm1*60LL + ss1) * 100LL + ms1;
  73         *duration = end - *start;
  74
  75         av_bprint_clear(dst);
  76         av_bprintf(dst, "%u,%d,%s", ass->readorder++, layer, p + pos);
  77         if (!av_bprint_is_complete(dst))
  78             return AVERROR(ENOMEM);
  79
  80         /* right strip the buffer */
  81         while (dst->len > 0 &&
  82                dst->str[dst->len - 1] == '\r' ||
  83                dst->str[dst->len - 1] == '\n')
  84             dst->str[--dst->len] = 0;
  85         return 0;
  86     }
  87     return -1;
  88 }
  89
  90 static int64_t get_line(AVBPrint *buf, FFTextReader *tr)
  91 {
  92     int64_t pos = ff_text_pos(tr);
  93
  94     av_bprint_clear(buf);
  95     for (;;) {
  96         char c = ff_text_r8(tr);
  97         if (!c)
  98             break;
  99         av_bprint_chars(buf, c, 1);
 100         if (c == '\n')
 101             break;
 102     }
 103     return pos;
 104 }
 105
 106 static int ass_read_header(AVFormatContext *s)
 107 {
 108     ASSContext *ass = s->priv_data;
 109     AVBPrint header, line, rline;
 110     int res = 0;
 111     AVStream *st;
 112     FFTextReader tr;
 113     ff_text_init_avio(s, &tr, s->pb);
 114
 115     st = avformat_new_stream(s, NULL);
 116     if (!st)
 117         return AVERROR(ENOMEM);
 118     avpriv_set_pts_info(st, 64, 1, 100);
 119     st->codecpar->codec_type = AVMEDIA_TYPE_SUBTITLE;
 120     st->codecpar->codec_id   = AV_CODEC_ID_ASS;
 121
 122     av_bprint_init(&header, 0, AV_BPRINT_SIZE_UNLIMITED);
 123     av_bprint_init(&line,   0, AV_BPRINT_SIZE_UNLIMITED);
 124     av_bprint_init(&rline,  0, AV_BPRINT_SIZE_UNLIMITED);
 125
 126     ass->q.keep_duplicates = 1;
 127
 128     for (;;) {
 129         int64_t pos = get_line(&line, &tr);
 130         int64_t ts_start = AV_NOPTS_VALUE;
 131         int duration = -1;
 132         AVPacket *sub;
 133
 134         if (!line.str[0]) // EOF
 135             break;
 136
 137         if (read_dialogue(ass, &rline, line.str, &ts_start, &duration) < 0) {
 138             av_bprintf(&header, "%s", line.str);
 139             continue;
 140         }
 141         sub = ff_subtitles_queue_insert_bprint(&ass->q, &rline, 0);
 142         if (!sub) {
 143             res = AVERROR(ENOMEM);
 144             goto end;
 145         }
 146         sub->pos = pos;
 147         sub->pts = ts_start;
 148         sub->duration = duration;
 149     }
 150
 151     res = ff_bprint_to_codecpar_extradata(st->codecpar, &header);
 152     if (res < 0)
 153         goto end;
 154
 155     ff_subtitles_queue_finalize(s, &ass->q);
 156
 157 end:
 158     av_bprint_finalize(&header, NULL);
 159     av_bprint_finalize(&line,   NULL);
 160     av_bprint_finalize(&rline,  NULL);
 161     return res;
 162 }
 163
 164 const FFInputFormat ff_ass_demuxer = {
 165     .p.name         = "ass",
 166     .p.long_name    = NULL_IF_CONFIG_SMALL("SSA (SubStation Alpha) subtitle"),
 167     .flags_internal = FF_INFMT_FLAG_INIT_CLEANUP,
 168     .priv_data_size = sizeof(ASSContext),
 169     .read_probe     = ass_probe,
 170     .read_header    = ass_read_header,
 171     .read_packet    = ff_subtitles_read_packet,
 172     .read_close     = ff_subtitles_read_close,
 173     .read_seek2     = ff_subtitles_read_seek,
 174 };