Burn-in output captions - MediaConvert
Where to specify the captionsHow to specify multiple captions tracksHow to use style passthroughHow to specify the font scriptNon-english fonts and unsupported characters

Burn-in output captions

This section covers how to configure burn-in output captions in AWS Elemental MediaConvert. The main topics include:

  • Where to specify the captions.

  • How to specify multiple captions tracks.

  • How to use style passthrough.

  • Non-english fonts and unsupported characters.

Burn-in is a way to deliver captions, rather than a captions format. Burn-in writes the captions directly on your video frames, replacing pixels of video content with the captions. If you want burn-in captions in an output, set up the captions according to the following information.

Where to specify the captions

Put your captions in the same output group and the same output as your video.

How to specify multiple captions tracks

You can burn in only one track of captions in each output.

How to use style passthrough

You can choose how to stylize the burn-in caption text that appears in your output video. There are a few options, including style passthrough, default settings, or manual overrides.

When you set Style passthrough to Enabled, MediaConvert uses the available style and position information from your input captions. Note that MediaConvert uses default settings for any missing style information.

MediaConvert supports style passthrough for the following input caption formats:

  • Ancillary

  • Embedded

  • SCTE-20

  • SCC

  • TTML

  • STL (EBU STL)

  • SMPTE-TT (text based)

  • Teletext

  • IMSC

  • WebVTT

When you set Style passthrough to Disabled, MediaConvert ignores style information from your input and uses default settings: white text with black outlining, bottom-center positioning, and automatic sizing.

Whether you set style passthrough to enabled or not, you can also choose to manually override any of the individual style options.

Note

TTML and TTML-like (IMSC, SMPTE-TT) inputs have special style formatting requirements. For more information, see TTML style formatting.

How to specify the font script

AWS Elemental MediaConvert automatically selects the appropriate script for your captions, based on the language that you specify in the output captions settings. If the language that you choose has more than one possible script, specify the script that you want.

To ensure that the service uses the correct font script

  1. In the Captions section under Encoding settings, for Language, choose the language of the captions text.

  2. If the language that you specify has more than one possible script, use Font script to specify the script.

    For example, if you choose Chinese (ZH) for Language, use Font script to choose either Simplified Chinese or Traditional Chinese. In this case, if you don’t specify a value for Font script, the service defaults to simplified Chinese.

    Tip

    In most cases, for Font script you can keep the default value of Automatic. When you do, the service chooses the script based on the language of the captions text.

Non-english fonts and unsupported characters

When your input font uses a non-English font script, your output burn-in captions may contain unsupported Unicode characters □. To resolve, set Style passthrough to Enabled.