How to Resolve “Invalid Subtitle Format” Issue

When performing video encoding on BlendVision One, you may encounter an error with “Invalid subtitle file format”. This issue usually arises from the original subtitle file (SRT format) input by the users. 


The common issues of SRT file are as below: 

  • Sequence of Numbers:Each subtitle paragraph should be in a sequence which  starts from 1 and increases progressively. If the sequence is wrong or missing, the subtitle may not display correctly. 
    • Checking method: Check each subtitle paragraph’s sequence in the file and confirm the sequence of numbers are continuous without omissions.

  • Timestamp Format: Timestamp determines when the subtitles display in the video. The wrong format will cause the subtitle to display at the wrong time or not at all.  
    • Format example: 00:01:30,500 --> 00:01:33,800 means the subtitle will display starting at 1 minute 30.5 seconds and ending at 1 minute 33.8 seconds.
    • Checking method: Timestamp Format should be “hh:mm:ss,ms --> hh:mm:ss,ms”. For example, 00:02:20,500 --> 00:02:23,000 means the subtitle display will start at 2 minutes 20.5 seconds and end at 2 minutes 23 seconds. Check if each subtitle paragraph follows this format. 
  • Non-Overlapping Timeframes: If the display times of multiple subtitles overlap, they will display simultaneously on the screen to cause confusion.
    • Checking method: Check start time and end time of each subtitle paragraph to confirm the start time of the next subtitle paragraph is not earlier than the end time of the previous one.

  • Non-Empty Subtitle Text: Each subtitle paragraph should include text.
    • Checking method: Check each subtitle paragraph in the SRT file to confirm there is corresponding text after each timestamp. 


Troubleshooting and Fix

We recommend you use [SRT Validator] ( tool to diagnose and fix the above common issues. Please operate with the steps below:


  1. Upload your SRT file: Click the above link to SRT Validator website, and click “UPLOAD FILE” to upload your SRT file. 
  2. Analyze from SRT Validator: After clicking “VALIDATE CAPTION”, SRT Validator will analyze your file automatically to search the above common issues.
  3. Check and edit: SRT Validator will list the existing issues in your file to assist you make corrections.
  4. Reupload to BlendVision One: Apply the revised subtitle file to your video encoding.

Advanced Tips

  • Before uploading the subtitle file to BlendVision , we suggest that you test subtitles to ensure they work normally on the local player. 
  • If subtitles display normally on the player, but issue occurs on BlendVision, the encoding settings may be not incompatible. If yes, please check  BlendVision's Supported Format and Encoded Parameter
  • We suggest you use UTF-8 or UTF-16 encoding to ensure that subtitles can display normally, especially the wording including special characters or non-English characters.