libavformat/assdec.c

   1 /*
   2  * SSA/ASS demuxer
   3  * Copyright (c) 2008 Michael Niedermayer
   4  *
   5  * This file is part of Libav.
   6  *
   7  * Libav 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  * Libav 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 Libav; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20  */
  21
  22 #include "libavutil/mathematics.h"
  23 #include "avformat.h"
  24 #include "internal.h"
  25
  26 #define MAX_LINESIZE 2000
  27
  28 typedef struct ASSContext{
  29     uint8_t *event_buffer;
  30     uint8_t **event;
  31     unsigned int event_count;
  32     unsigned int event_index;
  33 }ASSContext;
  34
  35 static int probe(AVProbeData *p)
  36 {
  37     const char *header= "[Script Info]";
  38
  39     if(   !memcmp(p->buf  , header, strlen(header))
  40        || !memcmp(p->buf+3, header, strlen(header)))
  41         return AVPROBE_SCORE_MAX;
  42
  43     return 0;
  44 }
  45
  46 static int read_close(AVFormatContext *s)
  47 {
  48     ASSContext *ass = s->priv_data;
  49
  50     av_freep(&ass->event_buffer);
  51     av_freep(&ass->event);
  52
  53     return 0;
  54 }
  55
  56 static int64_t get_pts(const uint8_t *p)
  57 {
  58     int hour, min, sec, hsec;
  59
  60     if(sscanf(p, "%*[^,],%d:%d:%d%*c%d", &hour, &min, &sec, &hsec) != 4)
  61         return AV_NOPTS_VALUE;
  62
  63     av_dlog(NULL, "%d %d %d %d [%s]\n", hour, min, sec, hsec, p);
  64
  65     min+= 60*hour;
  66     sec+= 60*min;
  67
  68     return sec*100+hsec;
  69 }
  70
  71 static int event_cmp(const void *_a, const void *_b)
  72 {
  73     const uint8_t *const *a = _a, *const *b = _b;
  74     return get_pts(*a) - get_pts(*b);
  75 }
  76
  77 static int read_header(AVFormatContext *s)
  78 {
  79     int i, len, header_remaining;
  80     ASSContext *ass = s->priv_data;
  81     AVIOContext *pb = s->pb;
  82     AVStream *st;
  83     int allocated[2]={0};
  84     uint8_t *p, **dst[2]={0};
  85     int pos[2]={0};
  86
  87     st = avformat_new_stream(s, NULL);
  88     if (!st)
  89         return -1;
  90     avpriv_set_pts_info(st, 64, 1, 100);
  91     st->codec->codec_type = AVMEDIA_TYPE_SUBTITLE;
  92     st->codec->codec_id= AV_CODEC_ID_SSA;
  93
  94     header_remaining= INT_MAX;
  95     dst[0] = &st->codec->extradata;
  96     dst[1] = &ass->event_buffer;
  97     while(!pb->eof_reached){
  98         uint8_t line[MAX_LINESIZE];
  99
 100         len = ff_get_line(pb, line, sizeof(line));
 101
 102         if(!memcmp(line, "[Events]", 8))
 103             header_remaining= 2;
 104         else if(line[0]=='[')
 105             header_remaining= INT_MAX;
 106
 107         i= header_remaining==0;
 108
 109         if(i && get_pts(line) == AV_NOPTS_VALUE)
 110             continue;
 111
 112         p = av_fast_realloc(*(dst[i]), &allocated[i], pos[i]+MAX_LINESIZE);
 113         if(!p)
 114             goto fail;
 115         *(dst[i])= p;
 116         memcpy(p + pos[i], line, len+1);
 117         pos[i] += len;
 118         if(i) ass->event_count++;
 119         else  header_remaining--;
 120     }
 121     st->codec->extradata_size= pos[0];
 122
 123     if(ass->event_count >= UINT_MAX / sizeof(*ass->event))
 124         goto fail;
 125
 126     ass->event= av_malloc(ass->event_count * sizeof(*ass->event));
 127     p= ass->event_buffer;
 128     for(i=0; i<ass->event_count; i++){
 129         ass->event[i]= p;
 130         while(*p && *p != '\n')
 131             p++;
 132         p++;
 133     }
 134
 135     qsort(ass->event, ass->event_count, sizeof(*ass->event), event_cmp);
 136
 137     return 0;
 138
 139 fail:
 140     read_close(s);
 141
 142     return -1;
 143 }
 144
 145 static int read_packet(AVFormatContext *s, AVPacket *pkt)
 146 {
 147     ASSContext *ass = s->priv_data;
 148     uint8_t *p, *end;
 149
 150     if(ass->event_index >= ass->event_count)
 151         return AVERROR(EIO);
 152
 153     p= ass->event[ ass->event_index ];
 154
 155     end= strchr(p, '\n');
 156     av_new_packet(pkt, end ? end-p+1 : strlen(p));
 157     pkt->flags |= AV_PKT_FLAG_KEY;
 158     pkt->pos= p - ass->event_buffer + s->streams[0]->codec->extradata_size;
 159     pkt->pts= pkt->dts= get_pts(p);
 160     memcpy(pkt->data, p, pkt->size);
 161
 162     ass->event_index++;
 163
 164     return 0;
 165 }
 166
 167 static int read_seek2(AVFormatContext *s, int stream_index,
 168                       int64_t min_ts, int64_t ts, int64_t max_ts, int flags)
 169 {
 170     ASSContext *ass = s->priv_data;
 171
 172     if (flags & AVSEEK_FLAG_BYTE) {
 173         return AVERROR(ENOSYS);
 174     } else if (flags & AVSEEK_FLAG_FRAME) {
 175         if (ts < 0 || ts >= ass->event_count)
 176             return AVERROR(ERANGE);
 177         ass->event_index = ts;
 178     } else {
 179         int i, idx = -1;
 180         int64_t min_ts_diff = INT64_MAX;
 181         if (stream_index == -1) {
 182             AVRational time_base = s->streams[0]->time_base;
 183             ts = av_rescale_q(ts, AV_TIME_BASE_Q, time_base);
 184             min_ts = av_rescale_rnd(min_ts, time_base.den,
 185                                     time_base.num * (int64_t)AV_TIME_BASE,
 186                                     AV_ROUND_UP);
 187             max_ts = av_rescale_rnd(max_ts, time_base.den,
 188                                     time_base.num * (int64_t)AV_TIME_BASE,
 189                                     AV_ROUND_DOWN);
 190         }
 191         /* TODO: ass->event[] is sorted by pts so we could do a binary search */
 192         for (i=0; i<ass->event_count; i++) {
 193             int64_t pts = get_pts(ass->event[i]);
 194             int64_t ts_diff = FFABS(pts - ts);
 195             if (pts >= min_ts && pts <= max_ts && ts_diff < min_ts_diff) {
 196                 min_ts_diff = ts_diff;
 197                 idx = i;
 198             }
 199         }
 200         if (idx < 0)
 201             return AVERROR(ERANGE);
 202         ass->event_index = idx;
 203     }
 204     return 0;
 205 }
 206
 207 AVInputFormat ff_ass_demuxer = {
 208     .name           = "ass",
 209     .long_name      = NULL_IF_CONFIG_SMALL("SSA (SubStation Alpha) subtitle"),
 210     .priv_data_size = sizeof(ASSContext),
 211     .read_probe     = probe,
 212     .read_header    = read_header,
 213     .read_packet    = read_packet,
 214     .read_close     = read_close,
 215     .read_seek2     = read_seek2,
 216 };