diff options
Diffstat (limited to 'libavformat/webvttdec.c')
| -rw-r--r-- | libavformat/webvttdec.c | 188 |
1 files changed, 188 insertions, 0 deletions
diff --git a/libavformat/webvttdec.c b/libavformat/webvttdec.c new file mode 100644 index 0000000000..b1cd2938ee --- /dev/null +++ b/libavformat/webvttdec.c @@ -0,0 +1,188 @@ +/* + * Copyright (c) 2012 Clément Bœsch + * + * This file is part of FFmpeg. + * + * FFmpeg is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; either + * version 2.1 of the License, or (at your option) any later version. + * + * FFmpeg is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with FFmpeg; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA + */ + +/** + * @file + * WebVTT subtitle demuxer + * @see http://dev.w3.org/html5/webvtt/ + */ + +#include "avformat.h" +#include "internal.h" +#include "subtitles.h" +#include "libavutil/bprint.h" +#include "libavutil/intreadwrite.h" + +typedef struct { + FFDemuxSubtitlesQueue q; +} WebVTTContext; + +static int webvtt_probe(AVProbeData *p) +{ + const uint8_t *ptr = p->buf; + + if (AV_RB24(ptr) == 0xEFBBBF) + ptr += 3; /* skip UTF-8 BOM */ + if (!strncmp(ptr, "WEBVTT", 6) && + (!ptr[6] || strchr("\n\r\t ", ptr[6]))) + return AVPROBE_SCORE_MAX; + return 0; +} + +static int64_t read_ts(const char *s) +{ + int hh, mm, ss, ms; + if (sscanf(s, "%u:%u:%u.%u", &hh, &mm, &ss, &ms) == 4) return (hh*3600 + mm*60 + ss) * 1000 + ms; + if (sscanf(s, "%u:%u.%u", &mm, &ss, &ms) == 3) return ( mm*60 + ss) * 1000 + ms; + return AV_NOPTS_VALUE; +} + +static int64_t extract_cue(AVBPrint *buf, AVIOContext *pb) +{ + int prev_chr_is_eol = 0; + int64_t pos = avio_tell(pb); + + av_bprint_clear(buf); + for (;;) { + char c = avio_r8(pb); + if (!c) + break; + if (c == '\r' || c == '\n') { + if (prev_chr_is_eol) + break; + prev_chr_is_eol = (c == '\n'); + } else + prev_chr_is_eol = 0; + if (c != '\r') + av_bprint_chars(buf, c, 1); + } + av_bprint_chars(buf, '\0', 1); + return pos; +} + +static int webvtt_read_header(AVFormatContext *s) +{ + WebVTTContext *webvtt = s->priv_data; + AVBPrint header, cue; + int res = 0; + AVStream *st = avformat_new_stream(s, NULL); + + if (!st) + return AVERROR(ENOMEM); + avpriv_set_pts_info(st, 64, 1, 1000); + st->codec->codec_type = AVMEDIA_TYPE_SUBTITLE; + st->codec->codec_id = AV_CODEC_ID_WEBVTT; + + av_bprint_init(&header, 0, AV_BPRINT_SIZE_UNLIMITED); + av_bprint_init(&cue, 0, AV_BPRINT_SIZE_UNLIMITED); + + for (;;) { + int i, len; + int64_t pos = extract_cue(&cue, s->pb); + AVPacket *sub; + const char *p = cue.str; + const char *identifier = p; + //const char *settings = NULL; + int64_t ts_start, ts_end; + + if (!*p) // EOF + break; + + /* ignore header chunk */ + if (!strncmp(p, "\xEF\xBB\xBFWEBVTT", 9) || + !strncmp(p, "WEBVTT", 6)) + continue; + + /* optional cue identifier (can be a number like in SRT or some kind of + * chaptering id), silently skip it */ + for (i = 0; p[i] && p[i] != '\n'; i++) { + if (!strncmp(p + i, "-->", 3)) { + identifier = NULL; + break; + } + } + if (identifier) + p += strcspn(p, "\n"); + + /* cue timestamps */ + if ((ts_start = read_ts(p)) == AV_NOPTS_VALUE) + break; + if (!(p = strstr(p, "-->"))) + break; + p += 3; + do p++; while (*p == ' ' || *p == '\t'); + if ((ts_end = read_ts(p)) == AV_NOPTS_VALUE) + break; + + /* optional cue settings, TODO: store in side_data */ + p += strcspn(p, "\n\t "); + while (*p == '\t' || *p == ' ') + p++; + if (*p != '\n') { + //settings = p; + p += strcspn(p, "\n"); + } + if (*p == '\n') + p++; + + /* create packet */ + len = cue.str + cue.len - p - 1; + sub = ff_subtitles_queue_insert(&webvtt->q, p, len, 0); + if (!sub) { + res = AVERROR(ENOMEM); + goto end; + } + sub->pos = pos; + sub->pts = ts_start; + sub->duration = ts_end - ts_start; + } + + ff_subtitles_queue_finalize(&webvtt->q); + +end: + av_bprint_finalize(&cue, NULL); + av_bprint_finalize(&header, NULL); + return res; +} + +static int webvtt_read_packet(AVFormatContext *s, AVPacket *pkt) +{ + WebVTTContext *webvtt = s->priv_data; + return ff_subtitles_queue_read_packet(&webvtt->q, pkt); +} + +static int webvtt_read_close(AVFormatContext *s) +{ + WebVTTContext *webvtt = s->priv_data; + ff_subtitles_queue_clean(&webvtt->q); + return 0; +} + +AVInputFormat ff_webvtt_demuxer = { + .name = "webvtt", + .long_name = NULL_IF_CONFIG_SMALL("WebVTT subtitle"), + .priv_data_size = sizeof(WebVTTContext), + .read_probe = webvtt_probe, + .read_header = webvtt_read_header, + .read_packet = webvtt_read_packet, + .read_close = webvtt_read_close, + .flags = AVFMT_GENERIC_INDEX, + .extensions = "vtt", +}; |