[FFmpeg-devel] [PATCH] [WIP] lavf: WebVTT demuxer and decoder.
Clément Bœsch
ubitux at gmail.com
Mon Sep 17 00:25:27 CEST 2012
On Thu, Sep 06, 2012 at 04:48:11AM +0200, Clément Bœsch wrote:
> TODO:
> - demuxer: export cue settings through side_data
> - decoder: honor at least the basic tags
> - lavf/lavc micro bump
> - Changelog entry
> ---
> Here we go, another WIP (sorry for the spam). I'm still not sure on how to
> factorize the tags parsing between lavc/webvttdec and lavc/srtdec, so for now
> I'm just skipping every markup (and also because we are still in meditation
> about a way to store the styles...).
>
> Maybe this WIP is good enough for a first version with an experimental bit, but
> there is nothing urgent for such support anyway.
> ---
The new attached version should be good enough for most of the common
cases. I'd like to push in a few days if there is no objection.
The decoder is pretty simple (it supports the common tags with a basic
search & replace with ASS tags), but it should be enough until we write
the new subtitles API.
Best regards,
--
Clément B.
-------------- next part --------------
From 862b55dedf482c6a8eeaac2c52245501624a2987 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Cl=C3=A9ment=20B=C5=93sch?= <ubitux at gmail.com>
Date: Sat, 1 Sep 2012 14:34:24 +0200
Subject: [PATCH] lavf: WebVTT demuxer and decoder.
TODO:
- lavf/lavc micro bump
- Changelog entry
---
doc/general.texi | 1 +
libavcodec/Makefile | 1 +
libavcodec/allcodecs.c | 1 +
libavcodec/avcodec.h | 1 +
libavcodec/codec_desc.c | 6 ++
libavcodec/webvttdec.c | 100 ++++++++++++++++++++++++
libavformat/Makefile | 1 +
libavformat/allformats.c | 1 +
libavformat/webvttdec.c | 188 ++++++++++++++++++++++++++++++++++++++++++++++
tests/fate/subtitles.mak | 3 +
tests/ref/fate/sub-webvtt | 1 +
11 files changed, 304 insertions(+)
create mode 100644 libavcodec/webvttdec.c
create mode 100644 libavformat/webvttdec.c
create mode 100644 tests/ref/fate/sub-webvtt
diff --git a/doc/general.texi b/doc/general.texi
index 45fd053..74ab3e0 100644
--- a/doc/general.texi
+++ b/doc/general.texi
@@ -898,6 +898,7 @@ performance on systems without hardware floating point support).
@item SubRip (SRT) @tab X @tab X @tab X @tab X
@item SubViewer @tab @tab X @tab @tab X
@item 3GPP Timed Text @tab @tab @tab X @tab X
+ at item WebVTT @tab @tab X @tab @tab X
@item XSUB @tab @tab @tab X @tab X
@end multitable
diff --git a/libavcodec/Makefile b/libavcodec/Makefile
index dd881b6..9b86f7c 100644
--- a/libavcodec/Makefile
+++ b/libavcodec/Makefile
@@ -463,6 +463,7 @@ OBJS-$(CONFIG_VP6_DECODER) += vp6.o vp56.o vp56data.o vp56dsp.o \
OBJS-$(CONFIG_VP8_DECODER) += vp8.o vp8dsp.o vp56rac.o
OBJS-$(CONFIG_VQA_DECODER) += vqavideo.o
OBJS-$(CONFIG_WAVPACK_DECODER) += wavpack.o
+OBJS-$(CONFIG_WEBVTT_DECODER) += webvttdec.o
OBJS-$(CONFIG_WMALOSSLESS_DECODER) += wmalosslessdec.o wma_common.o
OBJS-$(CONFIG_WMAPRO_DECODER) += wmaprodec.o wma.o wma_common.o
OBJS-$(CONFIG_WMAV1_DECODER) += wmadec.o wma.o wma_common.o aactab.o
diff --git a/libavcodec/allcodecs.c b/libavcodec/allcodecs.c
index 8806c6a..cba953f 100644
--- a/libavcodec/allcodecs.c
+++ b/libavcodec/allcodecs.c
@@ -422,6 +422,7 @@ void avcodec_register_all(void)
REGISTER_ENCDEC (SRT, srt);
REGISTER_ENCDEC (SUBRIP, subrip);
REGISTER_DECODER (SUBVIEWER, subviewer);
+ REGISTER_DECODER (WEBVTT, webvtt);
REGISTER_ENCDEC (XSUB, xsub);
/* external libraries */
diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
index 62a261a..74bebb9 100644
--- a/libavcodec/avcodec.h
+++ b/libavcodec/avcodec.h
@@ -448,6 +448,7 @@ enum AVCodecID {
AV_CODEC_ID_REALTEXT = MKBETAG('R','T','X','T'),
AV_CODEC_ID_SUBVIEWER = MKBETAG('S','u','b','V'),
AV_CODEC_ID_SUBRIP = MKBETAG('S','R','i','p'),
+ AV_CODEC_ID_WEBVTT = MKBETAG('W','V','T','T'),
/* other specific kind of codecs (generally used for attachments) */
AV_CODEC_ID_FIRST_UNKNOWN = 0x18000, ///< A dummy ID pointing at the start of various fake codecs.
diff --git a/libavcodec/codec_desc.c b/libavcodec/codec_desc.c
index 1f22b17..607dd96 100644
--- a/libavcodec/codec_desc.c
+++ b/libavcodec/codec_desc.c
@@ -2343,6 +2343,12 @@ static const AVCodecDescriptor codec_descriptors[] = {
.long_name = NULL_IF_CONFIG_SMALL("SubViewer subtitle"),
},
{
+ .id = AV_CODEC_ID_WEBVTT,
+ .type = AVMEDIA_TYPE_SUBTITLE,
+ .name = "webvtt",
+ .long_name = NULL_IF_CONFIG_SMALL("WebVTT subtitle"),
+ },
+ {
.id = AV_CODEC_ID_BINTEXT,
.type = AVMEDIA_TYPE_VIDEO,
.name = "bintext",
diff --git a/libavcodec/webvttdec.c b/libavcodec/webvttdec.c
new file mode 100644
index 0000000..6b86bed
--- /dev/null
+++ b/libavcodec/webvttdec.c
@@ -0,0 +1,100 @@
+/*
+ * 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 decoder
+ * @see http://dev.w3.org/html5/webvtt/
+ * @todo need to support extended markups and cue settings
+ */
+
+#include "avcodec.h"
+#include "ass.h"
+#include "libavutil/bprint.h"
+
+static const struct {
+ const char *from;
+ const char *to;
+} webvtt_tag_replace[] = {
+ {"<i>", "{\\i1}"}, {"</i>", "{\\i0}"},
+ {"<b>", "{\\b1}"}, {"</b>", "{\\b0}"},
+ {"<u>", "{\\u1}"}, {"</u>", "{\\u0}"},
+ {"{", "\\{"}, {"}", "\\}"}, // escape to avoid ASS markup conflicts
+};
+
+static int webvtt_event_to_ass(AVBPrint *buf, const char *p)
+{
+ int i, skip = 0;
+
+ while (*p) {
+
+ for (i = 0; i < FF_ARRAY_ELEMS(webvtt_tag_replace); i++) {
+ const char *from = webvtt_tag_replace[i].from;
+ const size_t len = strlen(from);
+ if (!strncmp(p, from, len)) {
+ av_bprintf(buf, "%s", webvtt_tag_replace[i].to);
+ p += len;
+ break;
+ }
+ }
+ if (!*p)
+ break;
+
+ if (*p == '<')
+ skip = 1;
+ else if (*p == '>')
+ skip = 0;
+ else if (p[0] == '\n' && p[1])
+ av_bprintf(buf, "\\N");
+ else if (!skip && *p != '\r')
+ av_bprint_chars(buf, *p, 1);
+ p++;
+ }
+ av_bprintf(buf, "\r\n");
+ return 0;
+}
+
+static int webvtt_decode_frame(AVCodecContext *avctx,
+ void *data, int *got_sub_ptr, AVPacket *avpkt)
+{
+ AVSubtitle *sub = data;
+ const char *ptr = avpkt->data;
+ AVBPrint buf;
+
+ av_bprint_init(&buf, 0, AV_BPRINT_SIZE_UNLIMITED);
+ if (ptr && avpkt->size > 0 && !webvtt_event_to_ass(&buf, ptr)) {
+ int ts_start = av_rescale_q(avpkt->pts, avctx->time_base, (AVRational){1,100});
+ int ts_duration = avpkt->duration != -1 ?
+ av_rescale_q(avpkt->duration, avctx->time_base, (AVRational){1,100}) : -1;
+ ff_ass_add_rect(sub, buf.str, ts_start, ts_duration, 0);
+ }
+ *got_sub_ptr = sub->num_rects > 0;
+ av_bprint_finalize(&buf, NULL);
+ return avpkt->size;
+}
+
+AVCodec ff_webvtt_decoder = {
+ .name = "webvtt",
+ .long_name = NULL_IF_CONFIG_SMALL("WebVTT subtitle"),
+ .type = AVMEDIA_TYPE_SUBTITLE,
+ .id = AV_CODEC_ID_WEBVTT,
+ .decode = webvtt_decode_frame,
+ .init = ff_ass_subtitle_header_default,
+};
diff --git a/libavformat/Makefile b/libavformat/Makefile
index c572e87..f1540ac 100644
--- a/libavformat/Makefile
+++ b/libavformat/Makefile
@@ -354,6 +354,7 @@ OBJS-$(CONFIG_WC3_DEMUXER) += wc3movie.o
OBJS-$(CONFIG_WEBM_MUXER) += matroskaenc.o matroska.o \
isom.o avc.o \
flacenc_header.o avlanguage.o
+OBJS-$(CONFIG_WEBVTT_DEMUXER) += webvttdec.o
OBJS-$(CONFIG_WSAUD_DEMUXER) += westwood_aud.o
OBJS-$(CONFIG_WSVQA_DEMUXER) += westwood_vqa.o
OBJS-$(CONFIG_WTV_DEMUXER) += wtvdec.o wtv.o asfdec.o asf.o asfcrypt.o \
diff --git a/libavformat/allformats.c b/libavformat/allformats.c
index 44ffd8a..3ff47ce 100644
--- a/libavformat/allformats.c
+++ b/libavformat/allformats.c
@@ -251,6 +251,7 @@ void av_register_all(void)
REGISTER_MUXDEMUX (WAV, wav);
REGISTER_DEMUXER (WC3, wc3);
REGISTER_MUXER (WEBM, webm);
+ REGISTER_DEMUXER (WEBVTT, webvtt);
REGISTER_DEMUXER (WSAUD, wsaud);
REGISTER_DEMUXER (WSVQA, wsvqa);
REGISTER_MUXDEMUX (WTV, wtv);
diff --git a/libavformat/webvttdec.c b/libavformat/webvttdec.c
new file mode 100644
index 0000000..b1cd293
--- /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",
+};
diff --git a/tests/fate/subtitles.mak b/tests/fate/subtitles.mak
index aa0b50d..d73352c 100644
--- a/tests/fate/subtitles.mak
+++ b/tests/fate/subtitles.mak
@@ -25,5 +25,8 @@ fate-sub-subripenc: CMD = md5 -i $(SAMPLES)/sub/MovText_capability_tester.mp4 -s
FATE_SUBTITLES += fate-sub-subviewer
fate-sub-subviewer: CMD = md5 -i $(SAMPLES)/sub/SubViewer_capability_tester.sub -f ass
+FATE_SUBTITLES += fate-sub-webvtt
+fate-sub-webvtt: CMD = md5 -i $(SAMPLES)/sub/WebVTT_capability_tester.vtt -f ass
+
FATE_SAMPLES_FFMPEG += $(FATE_SUBTITLES)
fate-subtitles: $(FATE_SUBTITLES)
diff --git a/tests/ref/fate/sub-webvtt b/tests/ref/fate/sub-webvtt
new file mode 100644
index 0000000..2e32e55
--- /dev/null
+++ b/tests/ref/fate/sub-webvtt
@@ -0,0 +1 @@
+5384a70c89ddca4b007fb7ffba95cffb
--
1.7.12
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 490 bytes
Desc: not available
URL: <http://ffmpeg.org/pipermail/ffmpeg-devel/attachments/20120917/39308af0/attachment.asc>
More information about the ffmpeg-devel
mailing list