Live Captions: Schedule Live Captions for an RTMP Stream

Once the Live Captioning module has been activated within 3Play Media, follow the steps below to schedule captions for an event using our RTMP workflow.

Note that events default to US-Eastern time unless a new timezone has been configured at the user level and configured for users outside of the US-Eastern time zone.


Navigate to the Live Captioning page

Click into the Live Captioning module within your 3Play Media project, and select “I want to caption another RTMP stream.”



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.


Event Start Time field


Add Event Name (optional)

Edit the event name if desired. If not edited, the default event name will be "Live Stream at MM/dd/yyyy, hh:mm:ss AM/PM".


Streaming to 3Play from your encoder 

To allow 3Play to receive your stream and create captions, you will stream to 3Play's caption service from your encoder. As a default, 3Play will provide you with a stream target (transcoder). The RTMP URL address and Key to the stream target are provided on the confirmation page of this workflow; you'll enter this information into your encoder stream settings in preparation for the event.

If you prefer to use your own transcoder, please check the box “Override 3Pay-provided RTMP URL and key” and enter your own RTMP URL and key information in the fields provided.




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


Set a Target Maximum Delay 

Drag the dial button to the right of the screen to increase the Target Maximum Delay and to the left of the screen to decrease the Target Maximum Delay in milliseconds. This sets a delay between the stream we receive and the captions we output. The more the delay, the more accurate the output.

Please note: Do not delay the stream within the hosting platform and/or encoding software/hardware.

Target Maximum Delay field


Filter Possibly Offensive Words

Select from the following options from the dropdown menu: None, Normal, High, or Strict to filter possibly offensive words. 

Please contact your Account Manager for more information about this setting.

Filter Possibly Offensive Words field


Set Event Wait Time

Enter an amount of time in minutes for our system to wait after the event has started if there is no audio.

Set Event Wait Time


Set Event Max Time

Enter the duration in minutes of the live event to be live captioned. 

Set Event Max Time field 

Note that this feature will determine the maximum length of the event and also act as a failsafe in case the streams are not manually stopped at the end of the live event.


Keep Stream?

Check the box next to Keep Stream? and 3Play Media will store the source video from a live event's RTMP stream. Keeping the stream will allow for additional services to be ordered upon completion of the event including an upgrade path to full transcription/captioning services.

If an RTMP is used but the option to capture the video is not selected, the source media can be added to live captioning file once the event has concluded to allow for other services to be ordered on the file.


Click Schedule Events & Copy Input RTMP URL & Key from confirmation page

Once the settings have been selected for the live captions for this event click Schedule Events.

3Play will provide you with an Input RTMP URL & Key on the confirmation page. Enter this information into your encoder.




Caption Delivery

Captions may be delivered to a captions embed, described below, or you may encode the captions to a 608 standard and restream to a supporting live player for native caption playback. The following section describes use of the captions embed.

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. 

live auto captioning embed code 

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 the 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

Click for information on how to encode the captions to a 608 standard and restream

Additional Options Upon Completion of the Live Event

Manage and Upgrade Live Captioning Files

Edit a Live Captioning File





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