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
28typedef struct ASSContext{
29    uint8_t *event_buffer;
30    uint8_t **event;
31    unsigned int event_count;
32    unsigned int event_index;
33}ASSContext;
34
35static 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
46static 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
56static 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_log(NULL, AV_LOG_ERROR, "%d %d %d %d %d [%s]\n", i, hour, min, sec, hsec, p);
64
65    min+= 60*hour;
66    sec+= 60*min;
67
68    return sec*100+hsec;
69}
70
71static int event_cmp(uint8_t **a, uint8_t **b)
72{
73    return get_pts(*a) - get_pts(*b);
74}
75
76static int read_header(AVFormatContext *s, AVFormatParameters *ap)
77{
78    int i, len, header_remaining;
79    ASSContext *ass = s->priv_data;
80    AVIOContext *pb = s->pb;
81    AVStream *st;
82    int allocated[2]={0};
83    uint8_t *p, **dst[2]={0};
84    int pos[2]={0};
85
86    st = avformat_new_stream(s, NULL);
87    if (!st)
88        return -1;
89    avpriv_set_pts_info(st, 64, 1, 100);
90    st->codec->codec_type = AVMEDIA_TYPE_SUBTITLE;
91    st->codec->codec_id= CODEC_ID_SSA;
92
93    header_remaining= INT_MAX;
94    dst[0] = &st->codec->extradata;
95    dst[1] = &ass->event_buffer;
96    while(!pb->eof_reached){
97        uint8_t line[MAX_LINESIZE];
98
99        len = ff_get_line(pb, line, sizeof(line));
100
101        if(!memcmp(line, "[Events]", 8))
102            header_remaining= 2;
103        else if(line[0]=='[')
104            header_remaining= INT_MAX;
105
106        i= header_remaining==0;
107
108        if(i && get_pts(line) == AV_NOPTS_VALUE)
109            continue;
110
111        p = av_fast_realloc(*(dst[i]), &allocated[i], pos[i]+MAX_LINESIZE);
112        if(!p)
113            goto fail;
114        *(dst[i])= p;
115        memcpy(p + pos[i], line, len+1);
116        pos[i] += len;
117        if(i) ass->event_count++;
118        else  header_remaining--;
119    }
120    st->codec->extradata_size= pos[0];
121
122    if(ass->event_count >= UINT_MAX / sizeof(*ass->event))
123        goto fail;
124
125    ass->event= av_malloc(ass->event_count * sizeof(*ass->event));
126    p= ass->event_buffer;
127    for(i=0; i<ass->event_count; i++){
128        ass->event[i]= p;
129        while(*p && *p != '\n')
130            p++;
131        p++;
132    }
133
134    qsort(ass->event, ass->event_count, sizeof(*ass->event), (void*)event_cmp);
135
136    return 0;
137
138fail:
139    read_close(s);
140
141    return -1;
142}
143
144static int read_packet(AVFormatContext *s, AVPacket *pkt)
145{
146    ASSContext *ass = s->priv_data;
147    uint8_t *p, *end;
148
149    if(ass->event_index >= ass->event_count)
150        return AVERROR(EIO);
151
152    p= ass->event[ ass->event_index ];
153
154    end= strchr(p, '\n');
155    av_new_packet(pkt, end ? end-p+1 : strlen(p));
156    pkt->flags |= AV_PKT_FLAG_KEY;
157    pkt->pos= p - ass->event_buffer + s->streams[0]->codec->extradata_size;
158    pkt->pts= pkt->dts= get_pts(p);
159    memcpy(pkt->data, p, pkt->size);
160
161    ass->event_index++;
162
163    return 0;
164}
165
166static int read_seek2(AVFormatContext *s, int stream_index,
167                      int64_t min_ts, int64_t ts, int64_t max_ts, int flags)
168{
169    ASSContext *ass = s->priv_data;
170
171    if (flags & AVSEEK_FLAG_BYTE) {
172        return AVERROR(ENOSYS);
173    } else if (flags & AVSEEK_FLAG_FRAME) {
174        if (ts < 0 || ts >= ass->event_count)
175            return AVERROR(ERANGE);
176        ass->event_index = ts;
177    } else {
178        int i, idx = -1;
179        int64_t min_ts_diff = INT64_MAX;
180        if (stream_index == -1) {
181            AVRational time_base = s->streams[0]->time_base;
182            ts = av_rescale_q(ts, AV_TIME_BASE_Q, time_base);
183            min_ts = av_rescale_rnd(min_ts, time_base.den,
184                                    time_base.num * (int64_t)AV_TIME_BASE,
185                                    AV_ROUND_UP);
186            max_ts = av_rescale_rnd(max_ts, time_base.den,
187                                    time_base.num * (int64_t)AV_TIME_BASE,
188                                    AV_ROUND_DOWN);
189        }
190        /* TODO: ass->event[] is sorted by pts so we could do a binary search */
191        for (i=0; i<ass->event_count; i++) {
192            int64_t pts = get_pts(ass->event[i]);
193            int64_t ts_diff = FFABS(pts - ts);
194            if (pts >= min_ts && pts <= max_ts && ts_diff < min_ts_diff) {
195                min_ts_diff = ts_diff;
196                idx = i;
197            }
198        }
199        if (idx < 0)
200            return AVERROR(ERANGE);
201        ass->event_index = idx;
202    }
203    return 0;
204}
205
206AVInputFormat ff_ass_demuxer = {
207    .name           = "ass",
208    .long_name      = NULL_IF_CONFIG_SMALL("Advanced SubStation Alpha subtitle format"),
209    .priv_data_size = sizeof(ASSContext),
210    .read_probe     = probe,
211    .read_header    = read_header,
212    .read_packet    = read_packet,
213    .read_close     = read_close,
214    .read_seek2     = read_seek2,
215};
216