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ffmpeg / libavformat / assdec.c @ 2912e87a

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/*
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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 Libav.
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 *
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 * Libav 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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 * Libav 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 Libav; 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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#include "internal.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 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, len, header_remaining;
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    ASSContext *ass = s->priv_data;
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    AVIOContext *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 = AVMEDIA_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(!pb->eof_reached){
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        uint8_t line[MAX_LINESIZE];
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        len = ff_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, len+1);
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        pos[i] += len;
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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 |= AV_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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static int read_seek2(AVFormatContext *s, int stream_index,
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                      int64_t min_ts, int64_t ts, int64_t max_ts, int flags)
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{
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    ASSContext *ass = s->priv_data;
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    if (flags & AVSEEK_FLAG_BYTE) {
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        return AVERROR_NOTSUPP;
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    } else if (flags & AVSEEK_FLAG_FRAME) {
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        if (ts < 0 || ts >= ass->event_count)
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            return AVERROR(ERANGE);
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        ass->event_index = ts;
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    } else {
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        int i, idx = -1;
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        int64_t min_ts_diff = INT64_MAX;
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        if (stream_index == -1) {
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            AVRational time_base = s->streams[0]->time_base;
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            ts = av_rescale_q(ts, AV_TIME_BASE_Q, time_base);
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            min_ts = av_rescale_rnd(min_ts, time_base.den,
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                                    time_base.num * (int64_t)AV_TIME_BASE,
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                                    AV_ROUND_UP);
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            max_ts = av_rescale_rnd(max_ts, time_base.den,
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                                    time_base.num * (int64_t)AV_TIME_BASE,
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                                    AV_ROUND_DOWN);
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        }
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        /* TODO: ass->event[] is sorted by pts so we could do a binary search */
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        for (i=0; i<ass->event_count; i++) {
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            int64_t pts = get_pts(ass->event[i]);
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            int64_t ts_diff = FFABS(pts - ts);
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            if (pts >= min_ts && pts <= max_ts && ts_diff < min_ts_diff) {
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                min_ts_diff = ts_diff;
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                idx = i;
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            }
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        }
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        if (idx < 0)
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            return AVERROR(ERANGE);
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        ass->event_index = idx;
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    }
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    return 0;
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}
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AVInputFormat ff_ass_demuxer = {
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    .name           = "ass",
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    .long_name      = NULL_IF_CONFIG_SMALL("Advanced SubStation Alpha subtitle format"),
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    .priv_data_size = sizeof(ASSContext),
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    .read_probe     = probe,
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    .read_header    = read_header,
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    .read_packet    = read_packet,
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    .read_close     = read_close,
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    .read_seek2     = read_seek2,
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};