yading@11: /*
yading@11:  * Copyright (c) 2012 Clément Bœsch
yading@11:  *
yading@11:  * This file is part of FFmpeg.
yading@11:  *
yading@11:  * FFmpeg is free software; you can redistribute it and/or
yading@11:  * modify it under the terms of the GNU Lesser General Public
yading@11:  * License as published by the Free Software Foundation; either
yading@11:  * version 2.1 of the License, or (at your option) any later version.
yading@11:  *
yading@11:  * FFmpeg is distributed in the hope that it will be useful,
yading@11:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
yading@11:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
yading@11:  * Lesser General Public License for more details.
yading@11:  *
yading@11:  * You should have received a copy of the GNU Lesser General Public
yading@11:  * License along with FFmpeg; if not, write to the Free Software
yading@11:  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
yading@11:  */
yading@11: 
yading@11: /**
yading@11:  * @file
yading@11:  * WebVTT subtitle demuxer
yading@11:  * @see http://dev.w3.org/html5/webvtt/
yading@11:  */
yading@11: 
yading@11: #include "avformat.h"
yading@11: #include "internal.h"
yading@11: #include "subtitles.h"
yading@11: #include "libavutil/bprint.h"
yading@11: #include "libavutil/intreadwrite.h"
yading@11: 
yading@11: typedef struct {
yading@11:     FFDemuxSubtitlesQueue q;
yading@11: } WebVTTContext;
yading@11: 
yading@11: static int webvtt_probe(AVProbeData *p)
yading@11: {
yading@11:     const uint8_t *ptr = p->buf;
yading@11: 
yading@11:     if (AV_RB24(ptr) == 0xEFBBBF)
yading@11:         ptr += 3;  /* skip UTF-8 BOM */
yading@11:     if (!strncmp(ptr, "WEBVTT", 6) &&
yading@11:         (!ptr[6] || strchr("\n\r\t ", ptr[6])))
yading@11:         return AVPROBE_SCORE_MAX;
yading@11:     return 0;
yading@11: }
yading@11: 
yading@11: static int64_t read_ts(const char *s)
yading@11: {
yading@11:     int hh, mm, ss, ms;
yading@11:     if (sscanf(s, "%u:%u:%u.%u", &hh, &mm, &ss, &ms) == 4) return (hh*3600LL + mm*60LL + ss) * 1000LL + ms;
yading@11:     if (sscanf(s,    "%u:%u.%u",      &mm, &ss, &ms) == 3) return (            mm*60LL + ss) * 1000LL + ms;
yading@11:     return AV_NOPTS_VALUE;
yading@11: }
yading@11: 
yading@11: static int webvtt_read_header(AVFormatContext *s)
yading@11: {
yading@11:     WebVTTContext *webvtt = s->priv_data;
yading@11:     AVBPrint header, cue;
yading@11:     int res = 0;
yading@11:     AVStream *st = avformat_new_stream(s, NULL);
yading@11: 
yading@11:     if (!st)
yading@11:         return AVERROR(ENOMEM);
yading@11:     avpriv_set_pts_info(st, 64, 1, 1000);
yading@11:     st->codec->codec_type = AVMEDIA_TYPE_SUBTITLE;
yading@11:     st->codec->codec_id   = AV_CODEC_ID_WEBVTT;
yading@11: 
yading@11:     av_bprint_init(&header, 0, AV_BPRINT_SIZE_UNLIMITED);
yading@11:     av_bprint_init(&cue,    0, AV_BPRINT_SIZE_UNLIMITED);
yading@11: 
yading@11:     for (;;) {
yading@11:         int i;
yading@11:         int64_t pos;
yading@11:         AVPacket *sub;
yading@11:         const char *p, *identifier;
yading@11:         //const char *settings = NULL;
yading@11:         int64_t ts_start, ts_end;
yading@11: 
yading@11:         ff_subtitles_read_chunk(s->pb, &cue);
yading@11: 
yading@11:         if (!cue.len)
yading@11:             break;
yading@11: 
yading@11:         p = identifier = cue.str;
yading@11:         pos = avio_tell(s->pb);
yading@11: 
yading@11:         /* ignore header chunk */
yading@11:         if (!strncmp(p, "\xEF\xBB\xBFWEBVTT", 9) ||
yading@11:             !strncmp(p, "WEBVTT", 6))
yading@11:             continue;
yading@11: 
yading@11:         /* optional cue identifier (can be a number like in SRT or some kind of
yading@11:          * chaptering id), silently skip it */
yading@11:         for (i = 0; p[i] && p[i] != '\n'; i++) {
yading@11:             if (!strncmp(p + i, "-->", 3)) {
yading@11:                 identifier = NULL;
yading@11:                 break;
yading@11:             }
yading@11:         }
yading@11:         if (identifier)
yading@11:             p += strcspn(p, "\n");
yading@11: 
yading@11:         /* cue timestamps */
yading@11:         if ((ts_start = read_ts(p)) == AV_NOPTS_VALUE)
yading@11:             break;
yading@11:         if (!(p = strstr(p, "-->")))
yading@11:             break;
yading@11:         p += 3;
yading@11:         do p++; while (*p == ' ' || *p == '\t');
yading@11:         if ((ts_end = read_ts(p)) == AV_NOPTS_VALUE)
yading@11:             break;
yading@11: 
yading@11:         /* optional cue settings, TODO: store in side_data */
yading@11:         p += strcspn(p, "\n\t ");
yading@11:         while (*p == '\t' || *p == ' ')
yading@11:             p++;
yading@11:         if (*p != '\n') {
yading@11:             //settings = p;
yading@11:             p += strcspn(p, "\n");
yading@11:         }
yading@11:         if (*p == '\n')
yading@11:             p++;
yading@11: 
yading@11:         /* create packet */
yading@11:         sub = ff_subtitles_queue_insert(&webvtt->q, p, strlen(p), 0);
yading@11:         if (!sub) {
yading@11:             res = AVERROR(ENOMEM);
yading@11:             goto end;
yading@11:         }
yading@11:         sub->pos = pos;
yading@11:         sub->pts = ts_start;
yading@11:         sub->duration = ts_end - ts_start;
yading@11:     }
yading@11: 
yading@11:     ff_subtitles_queue_finalize(&webvtt->q);
yading@11: 
yading@11: end:
yading@11:     av_bprint_finalize(&cue,    NULL);
yading@11:     av_bprint_finalize(&header, NULL);
yading@11:     return res;
yading@11: }
yading@11: 
yading@11: static int webvtt_read_packet(AVFormatContext *s, AVPacket *pkt)
yading@11: {
yading@11:     WebVTTContext *webvtt = s->priv_data;
yading@11:     return ff_subtitles_queue_read_packet(&webvtt->q, pkt);
yading@11: }
yading@11: 
yading@11: static int webvtt_read_seek(AVFormatContext *s, int stream_index,
yading@11:                             int64_t min_ts, int64_t ts, int64_t max_ts, int flags)
yading@11: {
yading@11:     WebVTTContext *webvtt = s->priv_data;
yading@11:     return ff_subtitles_queue_seek(&webvtt->q, s, stream_index,
yading@11:                                    min_ts, ts, max_ts, flags);
yading@11: }
yading@11: 
yading@11: static int webvtt_read_close(AVFormatContext *s)
yading@11: {
yading@11:     WebVTTContext *webvtt = s->priv_data;
yading@11:     ff_subtitles_queue_clean(&webvtt->q);
yading@11:     return 0;
yading@11: }
yading@11: 
yading@11: AVInputFormat ff_webvtt_demuxer = {
yading@11:     .name           = "webvtt",
yading@11:     .long_name      = NULL_IF_CONFIG_SMALL("WebVTT subtitle"),
yading@11:     .priv_data_size = sizeof(WebVTTContext),
yading@11:     .read_probe     = webvtt_probe,
yading@11:     .read_header    = webvtt_read_header,
yading@11:     .read_packet    = webvtt_read_packet,
yading@11:     .read_seek2     = webvtt_read_seek,
yading@11:     .read_close     = webvtt_read_close,
yading@11:     .extensions     = "vtt",
yading@11: };