WebVTT demuxer and decoder.

6 files changed, 110 insertions, 1 deletions

diff --git a/libavcodec/Makefile b/libavcodec/Makefile
index dd881b6c5b..9b86f7cef3 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 8806c6a598..cba953f825 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 e4bba5b090..0d643478f6 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 1f22b17242..607dd96f81 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/version.h b/libavcodec/version.h
index 7a779e6bce..c1d0b7669d 100644
--- a/libavcodec/version.h
+++ b/libavcodec/version.h
@@ -27,7 +27,7 @@
  */
 
 #define LIBAVCODEC_VERSION_MAJOR 54
-#define LIBAVCODEC_VERSION_MINOR 57
+#define LIBAVCODEC_VERSION_MINOR 58
 #define LIBAVCODEC_VERSION_MICRO 100
 
 #define LIBAVCODEC_VERSION_INT  AV_VERSION_INT(LIBAVCODEC_VERSION_MAJOR, \
diff --git a/libavcodec/webvttdec.c b/libavcodec/webvttdec.c
new file mode 100644
index 0000000000..6b86bedbe9
--- /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,
+};