add default property to sequence & closed captions

[erankor]

No description provided.

[aminvakil]

It works!

{
    "sequences": [
        {
            "clips": [
                {
                    "path": "/usr/share/nginx/html/multim3u8/once.mp4",
                    "type": "source"
                }
            ]
        },
        {
            "clips": [
                {
                    "path": "/usr/share/nginx/html/multim3u8/once.srt",
                    "type": "source"
                }
            ],
            "language": "en",
            "label": "English",
            "default": false
        }
    ]
}

results in:

#EXTM3U

#EXT-X-MEDIA:TYPE=SUBTITLES,GROUP-ID="subs0",NAME="English",LANGUAGE="en",AUTOSELECT=NO,DEFAULT=NO,URI="index-f2.m3u8"

#EXT-X-STREAM-INF:PROGRAM-ID=1,BANDWIDTH=2335290,RESOLUTION=1920x800,FRAME-RATE=23.974,CODECS="avc1.640029,mp4a.40.2",SUBTITLES="subs0"
index-f1-v1-a1.m3u8

#EXT-X-I-FRAME-STREAM-INF:BANDWIDTH=166759,RESOLUTION=1920x800,CODECS="avc1.640029",URI="iframes-f1-v1-a1.m3u8"

[aminvakil]

FWIW I cherry-picked the commit from this branch and added to 1.32 tag and built nginx with it.