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Add Automated Closed Captioning to Live Streams

Learn how to create, edit, and add automated native or translated captions to a channel when using different video sources.

Updated over a month ago

Introduction

Videolinq's EDIT offers a cost-effective and efficient way to add AI-Based automated native or translated captions to live streams while improving the accuracy of the output captions before they are inserted back into the broadcast. "Captions" refers to creating text from the native spoken language, while "Subtitles" are the creation of text translation from the native spoken language. This article will address all speech-to-text data created as "captions". Automated captions is a fee-based service. This article explains how to add GenAI captions to four types of video sources:

  • Connected Webcam or virtual meeting.

  • RTMP/RTSP (SRT coming soon) stream sent to Videolinq from a media encoder or virtual meeting.

  • RTMP/RTSP Stream (SRT coming soon) stream was pulled from the internet.

  • Pre-recorded media file or multiple files in a playlist.

Videolinq offers automated captions as three "outputs":

  • Closed Captioning - text is inserted to the video and available on compatible players with CC on/off option. Up to 3 source languages are supported, but only one output embed caption is available in the video.

  • Open Captioning - Text is embedded in the video and appears constantly. Up to 3 source languages are supported, but only one output caption appears on the video.

  • Data Feed - To display captions created in this mode, download the HTML page to show real-time subtitles on a projector or share it online for viewers to access on their phones. Alternatively, use the downloadable VTT manifest with any compatible HTML5 player to display multilingual subtitles during a live broadcast. The system supports up to 3 spoken source languages and delivers subtitles in up to 40 output languages through either the HTML page or the VTT manifest. This workflow is covered in a separate article.

Important:

  • Automated closed or open captions appear on live streams within 1, 2, or 3 minutes, depending on the delay chosen during task setup. The data feed appears on the HTML page or VTT manifest immediately.

  • When using the data feed output at 0 delay, captions will not show in the Editor.

  • To switch the automated captions method (e.g., from closed to open captions), follow these steps: stop the automated captions generation, stop all destinations, stop the channel, and stop the video source. Then, restart everything in reverse order: start the video source, select the proper captions mode, start the channel, start the captions, and finally, start the destinations.

All Videolinq plans have access to this feature, so let's get started!

Webcam/Virtual Meeting

Open the channel. Click on Sources. Click on the webcam or virtual meeting radio and "Update".

Expand the controls tab under the preview player and click on the Captions tab. Check the radio of the automated captions option. Last, push "Go Live".

When you see live video in the preview player it means the channel is active. Go back to the Captions tab. Select the required delay to edit the captions before they are inserted into the live stream. Drop down "Select Language" to match the audio source. Drop down "Translate" to select a target language, or set it to "None" if no translation is needed. Leave the "Language Model" as-is or try an alternative ti improve the output. Click on the "Start" icon to begin.

Wait about 60 seconds until you see captions in the preview player. Click on the "Editor" to access EDIT.

Real-time closed captioning will appear in EDIT. The red countdown number tells you how many seconds you have before the captions box disappears. Edit the text as needed. Click outside the text box to autosave changes. After the broadcast ends export SRT VTT or transcripts in PDF format.

When the live broadcast ends, do the following:

  • Stop video distribution to destinations.

  • Stop the automated closed captioning service (click on "Stop Captions").

  • Stop the channel (click on "Streaming"). The red icon will turn green "Go Live".

  • Stop the video source.

RTMP Encoder

First, read this article and learn how to configure your RTMP output stream. Next, open the channel. Click on Sources. Click on the RTMP radio and "Update".

Expand the controls tab under the preview player and click on the Captions tab. Check the radio of the automated closed captioning option.

Click and expand the Encoder tab. Copy the RTMP path and stream key to your preferred media encoder.

Start your media encoder. Confirm you see video in the preview player. Push "Go Live".

Go back to the Captions tab. Select the required delay to edit the captions before they are inserted into the live stream. Drop down "Select Language" to match the audio source. Drop down "Translate" to select a target language, or set it to "None" if no translation is needed. Leave the "Language Model" as-is or try an alternative ti improve the output. Click on the "Start" icon to begin.

Wait about 60 seconds until you see captions in the preview player. Click on the "Editor" to access EDIT.

Real-time closed captioning will appear in EDIT. The red countdown number tells you how many seconds you have before the captions box disappears. Edit the text as needed. Click outside the text box to autosave changes. After the broadcast ends export SRT VTT or transcripts in PDF format.

When the live broadcast ends do the following:

  • Stop video distribution to destinations.

  • Stop the automated closed captioning service (click on "Stop Captions").

  • Stop the channel (click on "Streaming"). The red icon will turn green "Go Live".

  • Stop the video source.

RTMP/RTSP Stream

Open the channel. Click on Sources. Click on the Stream radio, and place in the text box the RTMP or RTSP path to a live stream. Click "Update".

Expand the controls tab under the preview player and click on the Captions tab. Check the radio of the automated closed captioning option. Last, push "Go Live".

When you see live video in the preview player it means the channel is active. Go back to the Captions tab. Select the required delay to edit the captions before they are inserted into the live stream. Drop down "Select Language" to match the audio source. Drop down "Translate" to select a target language, or set it to "None" if no translation is needed. Leave the "Language Model" as-is or try an alternative ti improve the output. Click on the "Start" icon to begin.

Wait about 60 seconds until you see captions in the preview player. Click on the "Editor" to access EDIT.

Real-time closed captioning will appear in EDIT. The red countdown number tells you how many seconds you have before the captions box disappears. Edit the text as needed. Click outside the text box to autosave changes. After the broadcast ends export SRT VTT or transcripts in PDF format.

When the live broadcast ends do the following:

  • Stop video distribution to destinations.

  • Stop the automated closed captioning service (click on "Stop Captions").

  • Stop the channel (click on "Streaming"). The red icon will turn green "Go Live".

  • Stop the video source.

Recorded file(s)

Open the channel. Click on Sources. Click on the File radio. Upload recorded MP4 file, or drop down to select previously uploaded media. Click "Update".

Expand the controls tab under the preview player and click on the Captions tab. Check the radio of the automated closed captioning option. Last, push "Go Live".

When you see live video in the preview player it means the channel is active. Go back to the Captions tab. Select the required delay to edit the captions before they are inserted into the live stream. Drop down "Select Language" to match the audio source. Drop down "Translate" to select a target language, or set it to "None" if no translation is needed. Leave the "Language Model" as-is or try an alternative ti improve the output. Click on the "Start" icon to begin.

Wait about 60 seconds until you see captions in the preview player. Click on the "Editor" to access EDIT.

Real-time closed captioning will appear in EDIT. The red countdown number tells you how many seconds you have before the captions box disappears. Edit the text as needed. Click outside the text box to autosave changes. After the broadcast ends export SRT VTT or transcripts in PDF format.

When the live broadcast ends do the following:

  • Stop video distribution to destinations.

  • Stop the automated closed captioning service (click on "Stop Captions").

  • Stop the channel (click on "Streaming"). The red icon will turn green "Go Live".

  • Stop the video source.

Supported Languages

  • Automated closed captioning for live video is limited by the CEA-608 standard output and supports the display of closed captioning only in English, French, German, Spanish, Italian, Dutch, and Portuguese languages. However, the source language for live translation is available in 30+ languages: Arabic (15 dialects), Bengali, Bulgarian, Czech, Danish, Dutch, English (5 dialects), Finnish, French (2 dialects), German, Hindi, Hungarian, Indonesian, Italian, Japanese, Khmer, Korean, Macedonia, Malayalam, Norwegian, Polish, Portuguese, Romanian, Russian, Spanish (4 dialects), Swati, Swedish, Tamil, Telugu, Thai, Tsonga, Tswana, Turkish, Ukrainian, Venda, Vietnamese, and Xhosa.

  • Automated open captioning is supported in all 40 languages.

  • Data feed captions is supported as a 40 multi languages output.

Known issues our team is working on:

  1. Captions do not work well in iOS 13 and below in the Safari browser.

  2. Transcripts of some languages with non-Latin characters do not print well when exporting transcripts in PDF format.

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Tips & Tricks

Read below a few recommended steps our team prepared for new users of the service. Do you have questions about this service? Contact customer service by starting a chat conversation, on this page, or in the lower right corner of the media dashboard.

Technical Guidelines -

  1. Use high-quality audio equipment. Poor sound quality leads to missing or inaccurate captions. Use directional microphones when possible.

  2. Maintain proper microphone distance. Keep the mic at least 10 cm (5 inches) away from your mouth.

  3. Use a stable internet connection. A wired Ethernet connection is preferred over Wi-Fi for best performance.

  4. Use a device with a screen size of 1024 pixels or more for the best user experience.

  5. Avoid changing Editor delay settings during a live broadcast. If needed, stop the output stream first to prevent time shifts in the video.

  6. Real-time captions appears in 0, 1, 2, or 3 minutes, depending on whether you're using closed captions, open captions, or a data feed. in Data Feed mode, when using 0 delay, captions will not show in the Editor.

  7. Do not exceed 8 hours per captioning session. For longer events, stop the captioning service for 1 minute and restart it while keeping the stream live.

Operational Guidelines -

  1. Avoid speaking over each other. This helps the system capture clear, distinct speech.

  2. Wait 1 minute when switching between languages. Do not stop the live stream, unless you are changing the caption method (close captions, open captions, or data feed). Stop the captioning task, wait, then restart the task.

  3. Follow the proper shutdown order. First stop the destinations, then the captioning service, and finally the channel to avoid stream disruption.

  4. Hourly fees apply. Stop the automated captioning service when not in use to avoid unnecessary charges.

  5. Need to edit after the broadcast? Go to Sources > Content Management > Recorded Captions, find your file, rename, edit, and export.

This product is not necessarily ADA compliant, and we recommend that you also check with federal regulations to ensure compliance.

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