How to Convert Subtitle Files: SRT, VTT, TXT & JSON Conversion Guide

Why Convert Subtitle Formats?

Different platforms and applications require specific subtitle formats. Converting between SRT, VTT, TXT, and JSON ensures compatibility across all your video workflows.

Understanding Format Requirements

When You Need SRT

• Video players (VLC, Windows Media Player)
• Video editing software (Adobe Premiere, Final Cut Pro)
• Social media uploads (Facebook, Twitter)
• DVD/Blu-ray authoring

When You Need VTT

• HTML5 video players
• Web-based platforms
• Websites with custom styling
• Progressive web apps

When You Need TXT

• Translation workflows
• Content analysis
• SEO content generation
• Simple transcripts

When You Need JSON

• API responses
• Database storage
• Programming applications
• Custom subtitle processors

Method 1: Online Conversion Tools

Advantages

• No software installation
• Quick and easy
• Works on any device
• Free for most conversions

Popular Online Converters

• Rev.com (professional quality)
• Subtitle Tools (free, basic)
• GoTranscript Converter
• SubtitleConverter.net

Step-by-Step Process

1. Visit online converter
2. Upload your subtitle file
3. Select target format
4. Click convert
5. Download converted file

Method 2: Desktop Software

Subtitle Edit (Free, Windows)

Powerful open-source tool with extensive format support.

Features

• Batch conversion
• Timing adjustment
• Spell checking
• Sync correction

How to Convert

1. Open Subtitle Edit
2. File > Open (load your subtitle file)
3. File > Save As
4. Choose target format from dropdown
5. Save

Aegisub (Free, Cross-Platform)

Advanced subtitle editor with professional features.

Conversion Steps

1. Launch Aegisub
2. File > Open Subtitles
3. Select your file
4. File > Export Subtitles
5. Choose format and options
6. Export

Jubler (Free, Java-Based)

Simple cross-platform subtitle editor.

Method 3: Command Line Tools

FFmpeg (Advanced Users)

Powerful multimedia framework with subtitle conversion capabilities.

Basic Conversion Command

ffmpeg -i input.srt output.vtt

Common Conversions

# SRT to VTT
ffmpeg -i subtitles.srt subtitles.vtt

# VTT to SRT
ffmpeg -i subtitles.vtt subtitles.srt

Python Scripts

Create custom converters with Python libraries.

import pysrt

# Load SRT file
subs = pysrt.open('input.srt')

# Save as different format
subs.save('output.srt', encoding='utf-8')

Format-Specific Conversions

SRT to VTT

Manual Method

1. Add "WEBVTT" header at top
2. Change timestamp separator from comma to period
3. Optionally add cue settings

Example

SRT format:

1
00:00:01,000 --> 00:00:04,000
Hello world

VTT format:

WEBVTT

00:00:01.000 --> 00:00:04.000
Hello world

VTT to SRT

1. Remove "WEBVTT" header
2. Change periods to commas in timestamps
3. Remove cue settings
4. Strip styling tags

SRT/VTT to TXT

1. Extract text content only
2. Remove timestamps
3. Remove sequence numbers
4. Clean formatting

Any Format to JSON

1. Parse timestamps and text
2. Create JSON structure
3. Add metadata if needed
4. Export as .json file

Batch Conversion

Why Batch Convert?

• Convert multiple files simultaneously
• Save time on large projects
• Maintain consistent formatting

Batch Conversion Tools

• Subtitle Edit (Windows)
• FFmpeg with scripts
• Custom Python scripts
• Online batch converters

Quality Checks After Conversion

Verification Checklist

• Open converted file in text editor
• Check timestamps are intact
• Verify text content matches
• Test with video player
• Check character encoding (UTF-8)
• Verify line breaks and formatting

Common Issues

• Encoding problems: Special characters display incorrectly
• Lost formatting: Italics or colors removed
• Timing shifts: Timestamps don't match video
• Missing lines: Some subtitles disappear

Advanced Conversion Techniques

Preserving Styling (VTT)

When converting to VTT, you can add styling:

WEBVTT

NOTE styling
::cue {
  color: white;
  background-color: black;
}

00:00:01.000 --> 00:00:04.000
<c.yellow>Hello world</c>

Adding Metadata

JSON format allows rich metadata:

{
  "metadata": {
    "title": "Video Title",
    "language": "en",
    "created": "2025-01-01"
  },
  "subtitles": [...]
}

Mobile Conversion Apps

iOS Apps

• iSubtitle
• Sub Editor
• Subtitle Master

Android Apps

• Subtitle Converter
• SubRip Editor
• Easy Subtitle Converter

Automation and APIs

RESTful APIs

Integrate subtitle conversion into your applications:

• Subtitle Converter API
• Custom FFmpeg endpoints
• AWS Lambda functions

Workflow Automation

• Zapier integrations
• IFTTT recipes
• GitHub Actions
• CI/CD pipelines

Best Practices

Always Backup Originals

Keep original files before conversion in case of errors.

Use UTF-8 Encoding

Ensures compatibility with international characters.

Validate After Conversion

Test converted files with target application before production use.

Maintain Version Control

Track changes when editing or converting subtitles.

Troubleshooting Common Problems

Encoding Issues

Solution: Convert to UTF-8 encoding using tools like Notepad++ or iconv.

Timing Sync Problems

Solution: Use subtitle editors to adjust timing globally or per-subtitle.

Format Not Recognized

Solution: Verify file extension and content structure match expected format.

Special Characters Missing

Solution: Ensure proper encoding (UTF-8) throughout conversion process.

Platform-Specific Requirements

YouTube

Accepts: SRT, VTT, SBV. Recommended: SRT or VTT with UTF-8 encoding.

Vimeo

Accepts: SRT, VTT, DFXP. Recommended: VTT for web compatibility.

Facebook

Accepts: SRT. Must be UTF-8 encoded.

Netflix (Vendors)

Requires: Timed Text (TTML/DFXP) with specific formatting guidelines.

Conclusion

Converting subtitle formats is straightforward with the right tools. Whether using online converters for quick tasks, desktop software for advanced editing, or command-line tools for automation, understanding format requirements ensures smooth workflows across all video platforms.

Choose the method that best fits your technical comfort level and project requirements, and always verify conversions before final deployment.