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libavformat/assdec.c

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00001 /*
00002  * SSA/ASS demuxer
00003  * Copyright (c) 2008 Michael Niedermayer
00004  *
00005  * This file is part of FFmpeg.
00006  *
00007  * FFmpeg is free software; you can redistribute it and/or
00008  * modify it under the terms of the GNU Lesser General Public
00009  * License as published by the Free Software Foundation; either
00010  * version 2.1 of the License, or (at your option) any later version.
00011  *
00012  * FFmpeg is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00015  * Lesser General Public License for more details.
00016  *
00017  * You should have received a copy of the GNU Lesser General Public
00018  * License along with FFmpeg; if not, write to the Free Software
00019  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00020  */
00021 
00022 #include "avformat.h"
00023 #include "internal.h"
00024 
00025 #define MAX_LINESIZE 2000
00026 
00027 typedef struct ASSContext{
00028     uint8_t *event_buffer;
00029     uint8_t **event;
00030     unsigned int event_count;
00031     unsigned int event_index;
00032 }ASSContext;
00033 
00034 static int probe(AVProbeData *p)
00035 {
00036     const char *header= "[Script Info]";
00037 
00038     if(   !memcmp(p->buf  , header, strlen(header))
00039        || !memcmp(p->buf+3, header, strlen(header)))
00040         return AVPROBE_SCORE_MAX;
00041 
00042     return 0;
00043 }
00044 
00045 static int read_close(AVFormatContext *s)
00046 {
00047     ASSContext *ass = s->priv_data;
00048 
00049     av_freep(&ass->event_buffer);
00050     av_freep(&ass->event);
00051 
00052     return 0;
00053 }
00054 
00055 static int64_t get_pts(const uint8_t *p)
00056 {
00057     int hour, min, sec, hsec;
00058 
00059     if(sscanf(p, "%*[^,],%d:%d:%d%*c%d", &hour, &min, &sec, &hsec) != 4)
00060         return AV_NOPTS_VALUE;
00061 
00062 //    av_log(NULL, AV_LOG_ERROR, "%d %d %d %d %d [%s]\n", i, hour, min, sec, hsec, p);
00063 
00064     min+= 60*hour;
00065     sec+= 60*min;
00066 
00067     return sec*100+hsec;
00068 }
00069 
00070 static int event_cmp(uint8_t **a, uint8_t **b)
00071 {
00072     return get_pts(*a) - get_pts(*b);
00073 }
00074 
00075 static int read_header(AVFormatContext *s, AVFormatParameters *ap)
00076 {
00077     int i, len, header_remaining;
00078     ASSContext *ass = s->priv_data;
00079     AVIOContext *pb = s->pb;
00080     AVStream *st;
00081     int allocated[2]={0};
00082     uint8_t *p, **dst[2]={0};
00083     int pos[2]={0};
00084 
00085     st = av_new_stream(s, 0);
00086     if (!st)
00087         return -1;
00088     av_set_pts_info(st, 64, 1, 100);
00089     st->codec->codec_type = AVMEDIA_TYPE_SUBTITLE;
00090     st->codec->codec_id= CODEC_ID_SSA;
00091 
00092     header_remaining= INT_MAX;
00093     dst[0] = &st->codec->extradata;
00094     dst[1] = &ass->event_buffer;
00095     while(!url_feof(pb)){
00096         uint8_t line[MAX_LINESIZE];
00097 
00098         len = ff_get_line(pb, line, sizeof(line));
00099 
00100         if(!memcmp(line, "[Events]", 8))
00101             header_remaining= 2;
00102         else if(line[0]=='[')
00103             header_remaining= INT_MAX;
00104 
00105         i= header_remaining==0;
00106 
00107         if(i && get_pts(line) == AV_NOPTS_VALUE)
00108             continue;
00109 
00110         p = av_fast_realloc(*(dst[i]), &allocated[i], pos[i]+MAX_LINESIZE);
00111         if(!p)
00112             goto fail;
00113         *(dst[i])= p;
00114         memcpy(p + pos[i], line, len+1);
00115         pos[i] += len;
00116         if(i) ass->event_count++;
00117         else  header_remaining--;
00118     }
00119     st->codec->extradata_size= pos[0];
00120 
00121     if(ass->event_count >= UINT_MAX / sizeof(*ass->event))
00122         goto fail;
00123 
00124     ass->event= av_malloc(ass->event_count * sizeof(*ass->event));
00125     p= ass->event_buffer;
00126     for(i=0; i<ass->event_count; i++){
00127         ass->event[i]= p;
00128         while(*p && *p != '\n')
00129             p++;
00130         p++;
00131     }
00132 
00133     qsort(ass->event, ass->event_count, sizeof(*ass->event), (void*)event_cmp);
00134 
00135     return 0;
00136 
00137 fail:
00138     read_close(s);
00139 
00140     return -1;
00141 }
00142 
00143 static int read_packet(AVFormatContext *s, AVPacket *pkt)
00144 {
00145     ASSContext *ass = s->priv_data;
00146     uint8_t *p, *end;
00147 
00148     if(ass->event_index >= ass->event_count)
00149         return AVERROR(EIO);
00150 
00151     p= ass->event[ ass->event_index ];
00152 
00153     end= strchr(p, '\n');
00154     av_new_packet(pkt, end ? end-p+1 : strlen(p));
00155     pkt->flags |= AV_PKT_FLAG_KEY;
00156     pkt->pos= p - ass->event_buffer + s->streams[0]->codec->extradata_size;
00157     pkt->pts= pkt->dts= get_pts(p);
00158     memcpy(pkt->data, p, pkt->size);
00159 
00160     ass->event_index++;
00161 
00162     return 0;
00163 }
00164 
00165 static int read_seek2(AVFormatContext *s, int stream_index,
00166                       int64_t min_ts, int64_t ts, int64_t max_ts, int flags)
00167 {
00168     ASSContext *ass = s->priv_data;
00169 
00170     if (flags & AVSEEK_FLAG_BYTE) {
00171         return AVERROR(ENOSYS);
00172     } else if (flags & AVSEEK_FLAG_FRAME) {
00173         if (ts < 0 || ts >= ass->event_count)
00174             return AVERROR(ERANGE);
00175         ass->event_index = ts;
00176     } else {
00177         int i, idx = -1;
00178         int64_t min_ts_diff = INT64_MAX;
00179         if (stream_index == -1) {
00180             AVRational time_base = s->streams[0]->time_base;
00181             ts = av_rescale_q(ts, AV_TIME_BASE_Q, time_base);
00182             min_ts = av_rescale_rnd(min_ts, time_base.den,
00183                                     time_base.num * (int64_t)AV_TIME_BASE,
00184                                     AV_ROUND_UP);
00185             max_ts = av_rescale_rnd(max_ts, time_base.den,
00186                                     time_base.num * (int64_t)AV_TIME_BASE,
00187                                     AV_ROUND_DOWN);
00188         }
00189         /* TODO: ass->event[] is sorted by pts so we could do a binary search */
00190         for (i=0; i<ass->event_count; i++) {
00191             int64_t pts = get_pts(ass->event[i]);
00192             int64_t ts_diff = FFABS(pts - ts);
00193             if (pts >= min_ts && pts <= max_ts && ts_diff < min_ts_diff) {
00194                 min_ts_diff = ts_diff;
00195                 idx = i;
00196             }
00197         }
00198         if (idx < 0)
00199             return AVERROR(ERANGE);
00200         ass->event_index = idx;
00201     }
00202     return 0;
00203 }
00204 
00205 AVInputFormat ff_ass_demuxer = {
00206     .name           = "ass",
00207     .long_name      = NULL_IF_CONFIG_SMALL("Advanced SubStation Alpha subtitle format"),
00208     .priv_data_size = sizeof(ASSContext),
00209     .read_probe     = probe,
00210     .read_header    = read_header,
00211     .read_packet    = read_packet,
00212     .read_close     = read_close,
00213     .read_seek2     = read_seek2,
00214 };

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