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Video Encoding Fails with Error Resulting In Invalid Captions Format Error in Playback

Symptoms

  • Video fails with Invalid captions format during playback.

  • Video Center clip failed to encode with error:

transcoder.m3u8vtt.postprocess

Cause

There is an illegal character in your clip's closed captions that causes the error. All XML reserved characters including ", <, >, & ' should not be included in the .vtt file.

Solution

  1. Go to the video and make sure the subtitle is failing, that means this guide will cover the scenario, look for Invalid captions format error

  2. Get video UUID

  3. Use to curl to get s3 subtitle path

    • Remember to change "replace_with_uuid" in the URL

    • First time you might need to install jq 

    brew install jq

  4. Look for the WEB_VTT file (“url” is an s3 path)

  5. In the WEB_VTT file, look for any bad or illegal characters

  6. If you cannot find any and are still having issues, submit an ACS ticket

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