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Send Captions to Castr (RTMP 608)

Insert real-time captions into a live stream being sent to Castr using a SyncWords Service in a few easy steps.

Step 1 - Create a Service

In SyncWords, create a new service or navigate to your existing service configuration. Please see Step 1: General Settings - How do I create a Service using the new UI? for more information.

Step 2 - Provide Input Media

From the Input Media section, select RTMP PUSH. This determines how your live stream is received by the Service for processing. 



Please see Step 2: Input Media (RTMP) - How do I use RTMP as an Input source for my Service using the new UI? for more information.

If you already have an existing Service with RTMP selected on the Input, copy the values generated and enter them into your existing live streaming software or service (OBS, Wirecast, Streamyard, etc.) to send your stream to SyncWords.

 

IMPORTANT:

  • The audio sample rate of any incoming stream needs to be set to 44.1 kHz
  • The frame rate should be 29.97 or 30 fps
  • The video bitrate should be set to a minimum of 3,500 Kbps
  • The keyframe interval should be set to 2 seconds
  • The aspect ratio should be 16x9 or 4x3

Step 3 - Set up Transcription

Now that we have set up the incoming stream we need to set up the Transcript section to create the captions.

Configure the transcription settings to create captions from your live stream audio. 
Please see Step 3: Transcription - How do I enable Transcription for my Service using the new UI? for more information.

Step 4 - Set up Translations (optional)

If you need translations, you can add real-time AI text translations and audio dubbing to your live stream.

Please see Step 4: Translation - How do I enable Translation for my Service using the new UI? for more information.

WARNING: RTMP output only supports languages using Latin character sets, so picking a language like Arabic would not work.

 

Step 5 - Set up the Output

The last step is to set up the stream that will go out to one or more RTMP endpoints with the embedded 608 captions. In your SyncWords Service configuration, navigate to the Output section select RTMP - PUSH and add at least one destination.

You can now also send multiple RTMP output destinations to stream simultaneously to platforms like YouTube, Facebook, Castr and more. Please see Can I send my RTMP output to multiple destinations? for more information.

NOTE: We will go over where to get those values from Castr below in case you are not familiar with their setup. 



Make sure the "Embedded 608" is enabled under Captions & Subtitles. Make sure to click "Continue" once your selections are set. This moves to the next step where you can preview your Service settings.

Please see Step 5: Output (RTMP) - How do I configure RTMP Output for my Service using the new UI? for more information.

 

Step 6 - Getting the Stream URL and Key from Castr

  • In Castr, click on Livestreams on the left and then the Create New button.

 

  • Stream name: Give your stream a name

  • Ingest Location: Select the region closest to your broadcast and then click Create Livestream to create your livestream. 

  • Once the Livestream has been created, you can change the assigned region at any time by clicking Source Setup beneath the preview window on the right and selecting the desired region. 

 

IMPORTANT: Changing the region will alter your RTMP/SRT URL. Please ensure to update the RTMP details on SyncWords Live accordingly.

  • In the livestream, go to Settings > Player Functions > Turn on Enable Caption Support.

WARNING: If Enable Caption Support is not turned on, the captions will not show up in your stream.

  • From the Source Setup, under Publish > RTMP on your Livestream, grab the RTMP URL and Streaming Key to paste into the corresponding Output fields on SyncWords Live.

 

You are set! Once you start streaming to SyncWords Live, the stream with the embedded 608 captions will be sent to Castr and you will see that the stream is live in the preview window on the right side of the page.

 

You can view the stream with the embedded 608 captions either by embedding an iframe with the player into your event website using the iframe or directly by opening Castr player on a browser using the Direct Player Link under the Playback tab of your livestream.

Viewers can turn on the captions by clicking on the captions icon on the bottom right of the player and selecting CC1.


WARNING: You must start your SyncWords Service in order for it to accept incoming streams and deliver an output.