CEA-608/708 subtitles support in SLDP

CEA-608/708 closed captions are now supported in SLDP low latency playback protocol by Softvelum, in both Nimble Streamer and SLDP HTML5 Player.

The pipeline works as follows:

1. Closed captions are delivered in NAL units of your content via any live streaming protocol supported by Nimble Streamer, including SRT, RTMP, MPEGTS and others.
2. Nimble Streamer delivers the content via SLDP as usual.
3. SLDP HTML5 Player recognizes subtitles in the stream.
4. End user may enable subtitles display and watch video with closed captioning.

Notice that subtitles processing works only with SLDP Player SDK which is available as a premium product. Learn more about HTML5 Player SDK here. You can subscribe to SDK in order to generate the package for your domains and get our team's support going forward.

You can try this feature with our players testing free page before purchasing the SDK.

Please also take a look at Subtitles digest page to see what else Nimble can do for you.

Let us know if you have any questions about closed captioning in Softvelum products.

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Forward CEA-708 subtitles with Nimble Streamer

Providing subtitles as part of live streaming is important and is required by law is some countries. So people ask adding that capability into Nimble Streamer in addition to VOD subtitles support.

There are cases when source stream which comes into Nimble Streamer already contains subtitles metainformation. So now Nimble allows forwarding CEA-708 subtitles. This means that all outgoing streams for all supported protocols will include subtitles.

This works for both transmuxing and transcoding of H.264 (AVC) content.

Transmuxing support this forwarding by default. Whatever metainformation is inserted into the original stream, it is passed through to all other protocols.

To make this work in Live Transcoder scenarios, you need to enable this feature for outgoing streams. It's a premium add-on for this media server and it has easy-to-use web UI to control transcoding behavior. To install and get a license for it, visit this page.
To enable this feature for particular encoded stream, you need to edit an encoder block for the stream which you want subtitles to be forwarded for.

Transcoder scenario

Click on encoder details icon to open encoder details dialog.

Check the Forward CEA-708 subtitles box and save settings to close the dialog. Then click Save on scenario age to apply it on server.

That's it - the forwarding will start working right after a scenario is saved on server.


Also take a look at DVB subtitles processing and SCTE-35 processing which can also be passed through Live Transcoder.

Please also check Subtitles digest page to see what else Nimble can do for you.

Feel free to visit Live Transcoder webpage for other transcoding features description and contact us if you have any question.

Related documentation

Live Transcoder for Nimble Streamer, Live Streaming features, VOD subtitles support