Some player technologies allow a caption file to be specified as a URL and served as a separate HTTP request to the player. This article describes how to use the HTTPProviderCaptionFile HTTP provider in Wowza Streaming Engine™ media server software to enable the server to pull the requested caption file from its [install-dir]/content folder and stream the caption text to the player.
Note: Wowza Streaming Engine 4.7.1 or later is required.
Configure the HTTP provider
- Open the [install-dir]/conf/VHost.xml file in a text editor.
- Add the following HTTPProviderCaptionFile definition to the <VHost>/<HostPortList>/<HostPort>/<HTTPProviders> container. Be sure to put the HTTP provider in the <HostPort> container with the port value that you want to use (for example, port 1935). You must place the new HTTPProviderCaptionFile definition before the HTTPServerVersion HTTP provider definition.
<HTTPProvider>
<BaseClass>com.wowza.wms.timedtext.http.HTTPProviderCaptionFile</BaseClass>
<RequestFilters>*.ttml|*.srt|*.scc|*.vtt</RequestFilters>
<AuthenticationMethod>none</AuthenticationMethod>
</HTTPProvider>
Add the file extensions to be returned in <RequestFilters>. Separate each file extension with a pipe (|) character. In the above example, the HTTP provider will look for caption files with .ttml, .srt, .scc, and .vtt file extensions.
- Save and close VHost.xml, and then restart Wowza Streaming Engine.
- Add your caption files to the Wowza Streaming Engine content folder at [install-dir]/content.
Store caption files in subdirectories
To store files in subdirectories in [install-dir]/content, add the application instance (_definst_ by default) and the name of the subdirectory folder after the application name in the stream URL. The following example uses a caption file named myCaptions.ttml located in [install-dir]/content/subdir:
http://[address]:1935/myApplication/_definst_/subdir/myCaptions.ttml
Test the caption file
Test your HTTP provider configuration outside of players to verify that the caption file is returned correctly. To do this, use a Wget or cURL command from a command line. For example:
curl http://[address]:1935/myApplication/myCaptions.srt
To test for correct caption file return when using a subdirectory, use a cURL command with the following format:
curl http://[address]:1935/myApplication/_definst_/subdir/myCaptions.ttml
Specify external caption files in JW Player
JW Player 5 and later can specify external caption files using the SRT format. The following example code uses JW Player and external caption code to embed a VOD asset with two SRT caption files streamed with Apple HLS from Wowza Streaming Engine.
<script type="text/javascript">
jwplayer("mediaplayer").setup({
file: 'mp4:sample.mp4',
flashplayer: 'jwplayer5/player.swf',
height: 300,
plugins: {
'jwplayer5/captions.swf': {
files: "http://[address]:1935/myApplication/sample_eng.srt,http://[address]:1935/myApplication2/sample_kor.srt",
labels: "English,Korean",
}
},
streamer: 'rtmp://[address]:1935/myApplication',
width: 400
});
</script>
Specify external caption files in HTML5
Use the <track> HTML tag to specify subtitles or captions in a <video> object. The following example HTML code embeds a VOD asset with two WebVTT caption files streamed over Apple HLS from Wowza Streaming Engine.
<video width=400 height=300 src="http://[address]:1935/myApplication/mp4:sample.mp4/playlist.m3u8"> <track kind="subtitles" label="English subtitles" src="http://[address]:1935/myApplication/sample_eng.vtt" srclang="eng" default></track> <track kind="subtitles" label="Korean subtitles" src="http://[address]:1935/myApplication/sample_kor.vtt" srclang="kor"></track> </video>
