lavf: add WebVTT muxer.

This revision creates a WebVTT muxer, that outputs files having the
format described in the following specification:

http://dev.w3.org/html5/webvtt/

doc/general.texi

@@ -962,7 +962,7 @@ performance on systems without hardware floating point support).
 @item TED Talks captions @tab @tab X @tab   @tab X
 @item VobSub (IDX+SUB) @tab   @tab X @tab   @tab X
 @item VPlayer          @tab   @tab X @tab   @tab X
-@item WebVTT           @tab   @tab X @tab   @tab X
+@item WebVTT           @tab X @tab X @tab   @tab X
 @item XSUB             @tab   @tab   @tab X @tab X
 @end multitable
 

libavformat/Makefile

@@ -395,6 +395,7 @@ OBJS-$(CONFIG_WEBM_MUXER)                += matroskaenc.o matroska.o \
                                             isom.o avc.o \
                                             flacenc_header.o avlanguage.o wv.o
 OBJS-$(CONFIG_WEBVTT_DEMUXER)            += webvttdec.o subtitles.o
+OBJS-$(CONFIG_WEBVTT_MUXER)              += webvttenc.o
 OBJS-$(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 \

libavformat/allformats.c

@@ -292,7 +292,7 @@ void av_register_all(void)
     REGISTER_MUXDEMUX(WAV,              wav);
     REGISTER_DEMUXER (WC3,              wc3);
     REGISTER_MUXER   (WEBM,             webm);
-    REGISTER_DEMUXER (WEBVTT,           webvtt);
+    REGISTER_MUXDEMUX(WEBVTT,           webvtt);
     REGISTER_DEMUXER (WSAUD,            wsaud);
     REGISTER_DEMUXER (WSVQA,            wsvqa);
     REGISTER_MUXDEMUX(WTV,              wtv);

libavformat/version.h

@@ -30,8 +30,8 @@
 #include "libavutil/avutil.h"
 
 #define LIBAVFORMAT_VERSION_MAJOR 55
-#define LIBAVFORMAT_VERSION_MINOR  8
-#define LIBAVFORMAT_VERSION_MICRO 103
+#define LIBAVFORMAT_VERSION_MINOR  9
+#define LIBAVFORMAT_VERSION_MICRO 100
 
 #define LIBAVFORMAT_VERSION_INT AV_VERSION_INT(LIBAVFORMAT_VERSION_MAJOR, \
                                                LIBAVFORMAT_VERSION_MINOR, \

libavformat/webvttenc.c

+/*
+ * Copyright (c) 2013 Matthew Heaney
+ *
+ * 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 muxer
+ * @see http://dev.w3.org/html5/webvtt/
+ */
+
+#include "avformat.h"
+#include "internal.h"
+
+static void webvtt_write_time(AVIOContext *pb, int64_t millisec)
+{
+    int64_t sec, min, hour;
+    sec = millisec / 1000;
+    millisec -= 1000 * sec;
+    min = sec / 60;
+    sec -= 60 * min;
+    hour = min / 60;
+    min -= 60 * hour;
+
+    if (hour > 0)
+        avio_printf(pb, "%ld:", hour);
+
+    avio_printf(pb, "%02ld:%02ld.%03ld", min, sec, millisec);
+}
+
+static int webvtt_write_header(AVFormatContext *ctx)
+{
+    AVStream     *s = ctx->streams[0];
+    AVIOContext *pb = ctx->pb;
+
+    avpriv_set_pts_info(s, 64, 1, 1000);
+
+    avio_printf(pb, "WEBVTT\n");
+    avio_flush(pb);
+
+    return 0;
+}
+
+static int webvtt_write_packet(AVFormatContext *ctx, AVPacket *pkt)
+{
+    AVIOContext  *pb = ctx->pb;
+    int id_size, settings_size;
+    uint8_t *id, *settings;
+
+    avio_printf(pb, "\n");
+
+    id = av_packet_get_side_data(pkt, AV_PKT_DATA_WEBVTT_IDENTIFIER,
+                                 &id_size);
+
+    if (id && id_size > 0)
+        avio_printf(pb, "%.*s\n", id_size, id);
+
+    webvtt_write_time(pb, pkt->pts);
+    avio_printf(pb, " --> ");
+    webvtt_write_time(pb, pkt->pts + pkt->duration);
+
+    settings = av_packet_get_side_data(pkt, AV_PKT_DATA_WEBVTT_SETTINGS,
+                                       &settings_size);
+
+    if (settings && settings_size > 0)
+        avio_printf(pb, " %.*s", settings_size, settings);
+
+    avio_printf(pb, "\n");
+
+    avio_write(pb, pkt->data, pkt->size);
+    avio_printf(pb, "\n");
+
+    return 0;
+}
+
+AVOutputFormat ff_webvtt_muxer = {
+    .name              = "webvtt",
+    .long_name         = NULL_IF_CONFIG_SMALL("WebVTT subtitle"),
+    .extensions        = "vtt",
+    .mime_type         = "text/vtt",
+    .subtitle_codec    = AV_CODEC_ID_WEBVTT,
+    .write_header      = webvtt_write_header,
+    .write_packet      = webvtt_write_packet,
+};