libavformat/assdec.c

   1 /*
   2  * SSA/ASS demuxer
   3  * Copyright (c) 2008 Michael Niedermayer
   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
  24 #define MAX_LINESIZE 2000
  25
  26 typedef struct ASSContext{
  27     uint8_t *event_buffer;
  28     uint8_t **event;
  29     unsigned int event_count;
  30     unsigned int event_index;
  31 }ASSContext;
  32
  33 static void get_line(ByteIOContext *s, char *buf, int maxlen)
  34 {
  35     int i = 0;
  36     char c;
  37
  38     do{
  39         c = get_byte(s);
  40         if (i < maxlen-1)
  41             buf[i++] = c;
  42     }while(c != '\n' && c);
  43
  44     buf[i] = 0;
  45 }
  46
  47 static int probe(AVProbeData *p)
  48 {
  49     const char *header= "[Script Info]";
  50
  51     if(   !memcmp(p->buf  , header, strlen(header))
  52        || !memcmp(p->buf+3, header, strlen(header)))
  53         return AVPROBE_SCORE_MAX;
  54
  55     return 0;
  56 }
  57
  58 static int read_close(AVFormatContext *s)
  59 {
  60     ASSContext *ass = s->priv_data;
  61
  62     av_freep(&ass->event_buffer);
  63     av_freep(&ass->event);
  64
  65     return 0;
  66 }
  67
  68 static int64_t get_pts(const uint8_t *p)
  69 {
  70     int hour, min, sec, hsec;
  71
  72     if(sscanf(p, "%*[^,],%d:%d:%d%*c%d", &hour, &min, &sec, &hsec) != 4)
  73         return AV_NOPTS_VALUE;
  74
  75 //    av_log(NULL, AV_LOG_ERROR, "%d %d %d %d %d [%s]\n", i, hour, min, sec, hsec, p);
  76
  77     min+= 60*hour;
  78     sec+= 60*min;
  79
  80     return sec*100+hsec;
  81 }
  82
  83 static int event_cmp(uint8_t **a, uint8_t **b)
  84 {
  85     return get_pts(*a) - get_pts(*b);
  86 }
  87
  88 static int read_header(AVFormatContext *s, AVFormatParameters *ap)
  89 {
  90     int i, header_remaining;
  91     ASSContext *ass = s->priv_data;
  92     ByteIOContext *pb = s->pb;
  93     AVStream *st;
  94     int allocated[2]={0};
  95     uint8_t *p, **dst[2]={0};
  96     int pos[2]={0};
  97
  98     st = av_new_stream(s, 0);
  99     if (!st)
 100         return -1;
 101     av_set_pts_info(st, 64, 1, 100);
 102     st->codec->codec_type = CODEC_TYPE_SUBTITLE;
 103     st->codec->codec_id= CODEC_ID_SSA;
 104
 105     header_remaining= INT_MAX;
 106     dst[0] = &st->codec->extradata;
 107     dst[1] = &ass->event_buffer;
 108     while(!url_feof(pb)){
 109         uint8_t line[MAX_LINESIZE];
 110
 111         get_line(pb, line, sizeof(line));
 112
 113         if(!memcmp(line, "[Events]", 8))
 114             header_remaining= 2;
 115         else if(line[0]=='[')
 116             header_remaining= INT_MAX;
 117
 118         i= header_remaining==0;
 119
 120         if(i && get_pts(line) == AV_NOPTS_VALUE)
 121             continue;
 122
 123         p = av_fast_realloc(*(dst[i]), &allocated[i], pos[i]+MAX_LINESIZE);
 124         if(!p)
 125             goto fail;
 126         *(dst[i])= p;
 127         memcpy(p + pos[i], line, strlen(line)+1);
 128         pos[i] += strlen(line);
 129         if(i) ass->event_count++;
 130         else  header_remaining--;
 131     }
 132     st->codec->extradata_size= pos[0];
 133
 134     if(ass->event_count >= UINT_MAX / sizeof(*ass->event))
 135         goto fail;
 136
 137     ass->event= av_malloc(ass->event_count * sizeof(*ass->event));
 138     p= ass->event_buffer;
 139     for(i=0; i<ass->event_count; i++){
 140         ass->event[i]= p;
 141         while(*p && *p != '\n')
 142             p++;
 143         p++;
 144     }
 145
 146     qsort(ass->event, ass->event_count, sizeof(*ass->event), (void*)event_cmp);
 147
 148     return 0;
 149
 150 fail:
 151     read_close(s);
 152
 153     return -1;
 154 }
 155
 156 static int read_packet(AVFormatContext *s, AVPacket *pkt)
 157 {
 158     ASSContext *ass = s->priv_data;
 159     uint8_t *p, *end;
 160
 161     if(ass->event_index >= ass->event_count)
 162         return AVERROR(EIO);
 163
 164     p= ass->event[ ass->event_index ];
 165
 166     end= strchr(p, '\n');
 167     av_new_packet(pkt, end ? end-p+1 : strlen(p));
 168     pkt->flags |= PKT_FLAG_KEY;
 169     pkt->pos= p - ass->event_buffer + s->streams[0]->codec->extradata_size;
 170     pkt->pts= pkt->dts= get_pts(p);
 171     memcpy(pkt->data, p, pkt->size);
 172
 173     ass->event_index++;
 174
 175     return 0;
 176 }
 177
 178 AVInputFormat ass_demuxer = {
 179     "ass",
 180     NULL_IF_CONFIG_SMALL("SSA/ASS format"),
 181     sizeof(ASSContext),
 182     probe,
 183     read_header,
 184     read_packet,
 185     read_close,
 186 //    read_seek,
 187 };