3Play Live Virtual Encoding - Beta

Follow the steps below to schedule captions for a live captioning event with captions virtually encoded (CEA 608) into your RTMP stream. In this workflow you will stream from your video source (encoder) to 3Play, 3Play will provide you with an RTMP URL and Key to stream to from your encoder. Upon receiving your video stream, 3Play will encode your captions and restream the caption encoded stream to your provided Stream Target (typically your audience facing Live player).

Note that events default to US-Eastern time unless a new timezone has been configured at the user level.

Workflow diagram:



Key Notes:

  • 3Play is delaying the stream to your output Video/Event platform by 30 seconds to align the captions to the video stream (such that your audience should experience only 1-2 seconds of caption latency in relation to the event audio)
  • In this workflow, 3Play is streaming both video and captions to the end streaming platform - if you choose to End Event through the 3Play interface, this will also end the video stream. Do not select this unless you want to stop streaming your video. 
  • Additionally, if your stream to 3Play, or the 3Play stream to your specified restream URL is compromised, both captions and video will be impacted. As such we advise customers using this workflow run a secondary stream as a fallback.
  • You must successfully test your live caption setup at least one week prior to attempting to use it on a live, production event. The configuration you test should be the same used in production – troubleshooting a new setup at production time is rarely successful.


Navigate to Live Captioning in your 3Play account

As a first step, click into the Live Captioning module within your 3Play Media project, click “Schedule Captions” and select “Virtual Encoding”


Add Event Name

Add in a name for your event that will make it easy for you to find the event when searching for it after scheduling. 


Select Event Start Time

Click the calendar icon to choose the MM/DD/YYYY and HH:MM:SS of the event. The time will automatically be set to 5 minutes from the current time but can be manually edited within the field.

  • Please note: The live event must be scheduled at least 5 minutes in the future and it is editable up until 5 minutes prior to the scheduled start time. 3Play will initiate a service to listen for your stream at this time. Do not attempt to stream to 3Play before the event start time, as the stream connection will fail.



Select a File Storage Location

Choose a folder within your 3Play Media account to send your finished live transcript to after your event is over. 

File Storage Location

Choose a folder within your 3Play Media account to send your finished live transcript to after your event is over. 



Add Duration Information

Provide us with information regarding the duration of your event and what you would like us to do if your event goes over that duration. 


Select an Event Type

Tell us more about what captioner may be best for your event by selecting an accurate event type for us to categorize your event under. 



Provide an Event Description (optional)

Tell us more about your event with details to help our captioner research anything that they may need prior to your event starting. 


Provide a list of Speaker Names (optional) 

Provide us with a list of properly spelled speaker names for our captioners to use when captioning your event ( Live professional captioning ). 




Input Configuration

Enter a Pre-Event Start Time


Different from your event start time, the pre-event start time will tell us how many minutes before your event you'd like to start sending your stream to us. This is before your event start time, and will allow us to listen to your stream before your actual event start time. This is useful if you may start earlier than scheduled. 


Set Your Max Stream Time

Set your Stream Reconnection Wait Time

If your live stream disconnects during the event, this is how long we will wait before we disconnect from delivering captions. After this time has passed, you will no longer be able to connect to this event.


Enter Input RTMP URL & Key from your Stream Target 


Caption Delivery

In addition to in-player delivery, captions may be delivered to a captions embed, which is a code snippet (iFrame or Javascript) that can be added to a webpage (this requires access to the code through which the embed can be added). The following steps outline utilization of the captions embed.

3Play will also deliver captions to a second screen webpage, additional information on this captioning delivery method is available in this support document.


Note: With exception of a reserved embed or external web page, your caption link and embed code will be unique to each event. 


Caption Configuration

Set your Profanity Filter (optional)

Tell us how you'd like profanity in your event to be filtered, if at all. 


Provide a Wordlist (optional)  

To improve accuracy of automated captions for a scheduled Live Captioning event, add a Wordlist of the proper nouns, terms, and phrases unique to your organization that may be commonly used during the event. 

Click to learn more information regarding Wordlists for Live Captioning Events




Enter Support Contact Information

Please enter contact information for your event host or the person streaming your event to us in the event that 3Play Technical support needs to get in touch.


Click Submit

Click "Submit" on the right-hand side of the page to schedule your event once you have provided all of the necessary information. 



Copy Embed Code

Once scheduled, the 3Play Live Captioning embed code will be immediately available and then can be added to your live event page. 

Copy the iFrame embed code under Live Captioning Details to paste onto your webpage. While a JavaScript embed is available the iFrame is the preferred embed code for most uses. The Javascript embed allows for advanced customization.


Please note: This embed code only contains the text/captions and not the video.

Click for information on how to customize the Captions Embed


Once the Live Captioning event has been scheduled, event settings can be edited up to 5 minutes prior to the Event Start Time that was selected in step 2.

Click for information on how to edit the live caption's event settings for a scheduled event




Streaming specifications:

Please note, the transcoder handling your video stream is a passthrough transcoder, any streaming settings you configure will be maintained in your stream output. Please ensure that you are adhering to the streaming settings specified by your streaming destination. 

For more information on streaming best practices, follow this guidance: https://www.wowza.com/docs/encoding-best-practices-for-wowza-video-2 

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