avformat/webvttdec: Add webvtt extension and MIME type

The webvtt extension is sometimes used in HLS playlists.

Signed-off-by: softworkz <[email protected]>
Signed-off-by: Michael Niedermayer <[email protected]>

Author: softworkz

libavformat/webvttdec.c

@@ -216,7 +216,8 @@ static const AVClass webvtt_demuxer_class = {
 const FFInputFormat ff_webvtt_demuxer = {
     .p.name         = "webvtt",
     .p.long_name    = NULL_IF_CONFIG_SMALL("WebVTT subtitle"),
-    .p.extensions   = "vtt",
+    .p.mime_type    = "text/vtt",
+    .p.extensions   = "vtt,webvtt",
     .p.priv_class   = &webvtt_demuxer_class,
     .priv_data_size = sizeof(WebVTTContext),
     .flags_internal = FF_INFMT_FLAG_INIT_CLEANUP,