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![Michael Niedermayer](/assets/img/avatar_default.png)
The alternative (schoolbook) solution is less readable. Originally committed as revision 17230 to svn://svn.ffmpeg.org/ffmpeg/trunk
188 lines
4.4 KiB
C
188 lines
4.4 KiB
C
/*
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* SSA/ASS demuxer
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* Copyright (c) 2008 Michael Niedermayer
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "avformat.h"
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#define MAX_LINESIZE 2000
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typedef struct ASSContext{
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uint8_t *event_buffer;
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uint8_t **event;
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unsigned int event_count;
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unsigned int event_index;
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}ASSContext;
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static void get_line(ByteIOContext *s, char *buf, int maxlen)
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{
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int i = 0;
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char c;
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do{
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c = get_byte(s);
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if (i < maxlen-1)
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buf[i++] = c;
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}while(c != '\n' && c);
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buf[i] = 0;
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}
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static int probe(AVProbeData *p)
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{
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const char *header= "[Script Info]";
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if( !memcmp(p->buf , header, strlen(header))
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|| !memcmp(p->buf+3, header, strlen(header)))
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return AVPROBE_SCORE_MAX;
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return 0;
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}
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static int read_close(AVFormatContext *s)
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{
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ASSContext *ass = s->priv_data;
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av_freep(&ass->event_buffer);
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av_freep(&ass->event);
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return 0;
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}
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static int64_t get_pts(const uint8_t *p)
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{
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int hour, min, sec, hsec;
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if(sscanf(p, "%*[^,],%d:%d:%d%*c%d", &hour, &min, &sec, &hsec) != 4)
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return AV_NOPTS_VALUE;
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// av_log(NULL, AV_LOG_ERROR, "%d %d %d %d %d [%s]\n", i, hour, min, sec, hsec, p);
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min+= 60*hour;
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sec+= 60*min;
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return sec*100+hsec;
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}
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static int event_cmp(uint8_t **a, uint8_t **b)
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{
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return get_pts(*a) - get_pts(*b);
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}
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static int read_header(AVFormatContext *s, AVFormatParameters *ap)
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{
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int i, header_remaining;
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ASSContext *ass = s->priv_data;
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ByteIOContext *pb = s->pb;
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AVStream *st;
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int allocated[2]={0};
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uint8_t *p, **dst[2]={0};
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int pos[2]={0};
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st = av_new_stream(s, 0);
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if (!st)
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return -1;
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av_set_pts_info(st, 64, 1, 100);
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st->codec->codec_type = CODEC_TYPE_SUBTITLE;
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st->codec->codec_id= CODEC_ID_SSA;
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header_remaining= INT_MAX;
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dst[0] = &st->codec->extradata;
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dst[1] = &ass->event_buffer;
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while(!url_feof(pb)){
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uint8_t line[MAX_LINESIZE];
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get_line(pb, line, sizeof(line));
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if(!memcmp(line, "[Events]", 8))
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header_remaining= 2;
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else if(line[0]=='[')
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header_remaining= INT_MAX;
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i= header_remaining==0;
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if(i && get_pts(line) == AV_NOPTS_VALUE)
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continue;
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p = av_fast_realloc(*(dst[i]), &allocated[i], pos[i]+MAX_LINESIZE);
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if(!p)
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goto fail;
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*(dst[i])= p;
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memcpy(p + pos[i], line, strlen(line)+1);
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pos[i] += strlen(line);
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if(i) ass->event_count++;
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else header_remaining--;
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}
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st->codec->extradata_size= pos[0];
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if(ass->event_count >= UINT_MAX / sizeof(*ass->event))
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goto fail;
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ass->event= av_malloc(ass->event_count * sizeof(*ass->event));
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p= ass->event_buffer;
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for(i=0; i<ass->event_count; i++){
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ass->event[i]= p;
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while(*p && *p != '\n')
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p++;
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p++;
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}
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qsort(ass->event, ass->event_count, sizeof(*ass->event), (void*)event_cmp);
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return 0;
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fail:
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read_close(s);
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return -1;
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}
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static int read_packet(AVFormatContext *s, AVPacket *pkt)
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{
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ASSContext *ass = s->priv_data;
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uint8_t *p, *end;
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if(ass->event_index >= ass->event_count)
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return AVERROR(EIO);
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p= ass->event[ ass->event_index ];
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end= strchr(p, '\n');
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av_new_packet(pkt, end ? end-p+1 : strlen(p));
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pkt->flags |= PKT_FLAG_KEY;
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pkt->pos= p - ass->event_buffer + s->streams[0]->codec->extradata_size;
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pkt->pts= pkt->dts= get_pts(p);
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memcpy(pkt->data, p, pkt->size);
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ass->event_index++;
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return 0;
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}
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AVInputFormat ass_demuxer = {
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"ass",
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NULL_IF_CONFIG_SMALL("SSA/ASS format"),
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sizeof(ASSContext),
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probe,
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read_header,
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read_packet,
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read_close,
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// read_seek,
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};
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