Add 4ALL Closed Captions to vMix

Add an event-specific 4ALL Closed Captions URL to vMix as a transparent Web Browser Input, with an optional green background for chroma-key workflows.

Written By 4ALL.LIVE

Last updated 11 days ago

Use a 4ALL event’s Closed Captions URL as a Web Browser Input in vMix to place live captions over your program. The 4ALL full-view canvas is transparent by default, and vMix preserves browser alpha, so you normally do not need chroma keying, NDI, SDI fill/key, or a separate capture application.

If your production or a downstream device requires chroma keying, 4ALL also provides an optional solid view background. It starts at green (#00ff00) and can be changed.

Before you begin

  • Confirm the event is configured and producing captions from the intended audio source.

  • Confirm the Closed Captions output is available on your 4ALL plan (Pro, Scale, or Enterprise).

  • Choose the language that must appear in the vMix program.

  • Know the final production resolution, such as 1920 × 1080 or 3840 × 2160.

  • Arrange a program or return monitor so the operator can verify the composed output.

1. Prepare the Closed Captions output in 4ALL

  1. Open the event and go to Live Setup > Closed Captions.

  2. Enable the Closed Captions output.

  3. Select the output language required for the production.

  4. Configure the number of lines, maximum characters per line, width, horizontal and vertical position, bottom offset, and padding.

  5. Configure final and partial text styles. Enable only the text states the production needs, and decide whether to show speaker names.

  6. Optional: enable the caption background layer behind the text. Its color, opacity, blur, corner radius, and fit-to-text behavior are independent from the full-view canvas.

  7. Under View background, leave Use custom view background color off for native transparency.

  8. Open the event’s Share or Outputs control and copy the Closed Captions URL.

Copy the event-specific Closed Captions URL—not the attendee Viewer URL, dashboard URL, or an authenticated setup page.

2. Add the URL to vMix

  1. In vMix, click Add Input.

  2. Select Web Browser.

  3. Paste the 4ALL Closed Captions URL into the URL field.

  4. Set the Web Browser width and height to match the production canvas:

    • 1920 × 1080 for a 1080p production

    • 3840 × 2160 for a UHD production

  5. Click OK.

  6. On the new input, activate Overlay 1, Overlay 2, or another available Overlay channel to place the captions over the program.

  7. If needed, use Input Settings > Position for zoom, pan, or crop. Prefer adjusting placement in 4ALL first so the browser canvas remains predictable.

  8. Verify the captions in the final Program, External, stream, or recording output—not only in Preview.

Transparency: no keying is normally required

With the 4ALL custom view background disabled, the browser canvas is transparent. vMix Web Browser Inputs support transparency and alpha channels, and vMix respects alpha when the input is used as an overlay.

The optional bar immediately behind the caption text is a separate 4ALL design layer. You can keep that bar for readability while the rest of the 1920 × 1080 or 3840 × 2160 canvas remains transparent.

Optional: use a green background for chroma keying

Use this only when a downstream workflow explicitly requires a keyed video signal.

  1. In 4ALL Closed Captions, open View background.

  2. Enable Use custom view background color.

  3. The initial color is green (#00ff00). Choose another solid color if your production requires it.

  4. If you are keying inside vMix, open the input settings and configure Colour Key for the same color. Otherwise, pass the filled output to the downstream keyer.

  5. Check text edges and the final program monitor for spill or unwanted transparency.

Native alpha is preferred when it is available because it avoids keying artifacts around text.

Use separate inputs for multiple languages

The event-specific URL identifies the selected output language. If the production needs separate English, Spanish, or other language compositions, copy and preflight the correct Closed Captions URL for each language and create a separate vMix Web Browser Input for each output.

Preflight checklist

  • Confirm the correct event and language URL is loaded.

  • Test short phrases, long phrases, partial captions, final captions, and clearing behavior.

  • Check title-safe placement and readability over bright and dark shots.

  • Confirm the browser input dimensions match the production canvas.

  • Check the vMix Overlay channel and layer order.

  • Verify the result in Program, External output, the stream, and a test recording.

  • Practice refreshing or recreating the Web Browser Input.

  • Keep the event-specific URL private and share it only with authorized production operators.

Troubleshooting

No captions appear

Open the URL in a normal browser and confirm it receives text. Then verify the event is live, the Closed Captions output is enabled, the intended language is producing captions, the vMix input is online and visible, and an Overlay channel is active.

The browser input is black or opaque

In 4ALL, make sure Use custom view background color is off. Refresh or recreate the vMix Web Browser Input, remove unnecessary custom CSS or Colour Key settings, and confirm you added a Web Browser Input rather than capturing a browser window.

The full screen is green

The custom view background is enabled. Disable it to return to native transparency, or configure the matching key in vMix or the downstream device.

Captions are cropped, too small, or blurry

Match the Web Browser Input dimensions to the production output. Review 4ALL width and position settings, then reset or adjust vMix Position, zoom, pan, and crop. Avoid enlarging a low-resolution browser canvas.

Styles or captions look stale

Refresh the Web Browser Input after major style changes. If needed, remove and recreate the input using the same event-specific URL, then verify it again in Program.

Browser overlays versus embedded closed captions

Although 4ALL names this output Closed Captions, vMix composites the Web Browser Input into the visible picture. The resulting captions are open, or burned-in, captions that viewers cannot independently turn off.

If the video stream must carry selectable embedded CEA-608/708 caption data, use 4ALL Encoder and validate the service on a compatible downstream decoder.

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