Updated: June 3, 2025

The Caption Quality Analyzer evaluates multiple aspects of your caption files to ensure they meet professional accessibility and quality standards. Here’s exactly what we check:

📊 File Statistics & Basic Metrics

What we measure:

  • Total number of captions
  • Total video duration covered
  • Word count and character count
  • Average words per caption
  • Average caption duration

Standards reference: Basic quantitative analysis for content overview.

🔧 Technical Specifications

Supported File Formats

  • SRT (SubRip Subtitle) files
  • VTT (WebVTT) files
  • ASS/SSA (Advanced/Simple SubStation Alpha) files

File Size Limits

  • Maximum file size: 5MB
  • Processing time: Typically under 3 seconds
  • Browser compatibility: All modern browsers supported
  • Privacy protection: All analysis performed locally – files never stored or transmitted

Caption Standards Reported By This Tool

⏱️ Caption Timing Standards

Reading Speed Evaluation

  • Optimal range: Under 180 words per minute (WPM)
  • Warning threshold: 180-200 WPM
  • Critical threshold: Over 200 WPM
  • Standards source: DCMP Captioning Key guidelines for sustainable reading speeds that allow viewers to comfortably read captions while watching video

Caption Duration Standards

  • Minimum duration: 1 second per caption
  • Rationale: Ensures captions display long enough to be read
  • Standards source: DCMP best practices and broadcast television standards

Caption Spacing Analysis

  • Gap measurement: Time between consecutive captions
  • Overlap detection: Identifies when caption timecodes conflict
  • Flow analysis: Ensures reasonable pacing between captions
  • Standards source: Professional captioning workflow standards

Note: This analysis is based on caption file timing data only. It does not verify synchronization with actual audio or video content.

📝 Text Quality & Formatting

Line Length Compliance

  • Recommended maximum: 42 characters per line
  • Why it matters: Ensures readability across different screen sizes and devices
  • Standards source: DCMP Captioning Key and broadcast television formatting guidelines

Text Formatting Standards

  • Punctuation compliance: Checks for proper sentence endings
  • Case sensitivity: Flags excessive uppercase text (considered difficult to read and equivalent to “shouting”)
  • Line structure: Validates appropriate line breaks and formatting
  • Standards source: DCMP formatting guidelines and professional captioning style guides

Content Quality Checks

  • Character encoding: Validates proper text encoding for special characters
  • Sentence completion: Ensures captions end with appropriate punctuation
  • Formatting consistency: Checks for uniform styling across the caption file

♿ Accessibility & Universal
Design Compliance

Sound Effect Coverage

  • Detection method: Identifies sound effect descriptions using brackets [ ], parentheses ( ), and music notes ♪
  • Coverage analysis: Calculates percentage of captions that include non-speech audio information
  • Why it matters: Critical for deaf and hard-of-hearing viewers to understand full audio context
  • Standards source: Americans with Disabilities Act (ADA) requirements and DCMP Captioning Key best practices

Speaker Identification Analysis

  • Detection method: Identifies speaker attribution using patterns like “NAME:”, “SPEAKER:”, or similar formats
  • Coverage measurement: Calculates percentage of dialogue with clear speaker identification
  • Why it matters: Essential for following multi-speaker conversations, especially for deaf viewers
  • Standards source: DCMP best practices and accessibility guidelines for inclusive media

Visual Accessibility Compliance

  • Standards source: Web Content Accessibility Guidelines (WCAG) 2.1 Level AA standards
  • Color dependency detection: Flags use of color-only formatting codes that aren’t accessible to color-blind viewers
  • Format accessibility: Ensures caption formatting doesn’t rely solely on visual cues

🏛️ Standards Alignment &
Best Practices

Federal Accessibility Standards

  • Section 508: Rehabilitation Act requirements for federal technology accessibility
  • ADA Title III: Public accommodation accessibility requirements for businesses and organizations
  • 21st Century Communications and Video Accessibility Act (CVAA): FCC mandates for video programming accessibility

Professional Captioning Standards

  • DCMP Guidelines: Descriptive and Captioning Media Program best practices
  • Broadcasting Standards: Television industry formatting and quality requirements
  • Educational Standards: Section 504 and IDEA compliance for educational content

Quality Benchmarks

  • Sound effect coverage: Ensures comprehensive audio description for full accessibility
  • Reading speed limits: Based on cognitive load research and accessibility studies
  • Line length standards: Optimized for readability across devices and viewing conditions

📈 Comprehensive
Scoring System

Overall Quality Score (0-100)

Our algorithm combines multiple factors:

  • Timing Quality (33%): Reading speed compliance and caption duration standards
  • Text Quality (33%): Formatting, readability, and professional presentation standards
  • Accessibility (33%): Sound effects coverage, speaker identification, and universal design principles

Individual Category Scoring

  • Excellent (80-100 points): Meets or exceeds all professional captioning standards
  • Good (60-79 points): Meets most standards with minor improvements recommended
  • Needs Improvement (Below 60 points): Requires significant revision to meet accessibility standards

Detailed Issue Reporting

  • Specific location identification: Pinpoints exact caption numbers with issues
  • Severity classification: Distinguishes between critical accessibility issues and minor improvements
  • Actionable recommendations: Provides specific guidance for addressing each identified issue

📋 Analysis Limitations &
Scope

What We Analyze

  • Caption file content: Text, timing, and formatting within the caption file itself
  • Structural compliance: Adherence to formatting and accessibility standards
  • Readability metrics: Reading speed, line length, and text quality measures

What We Don’t Analyze

  • Audio synchronization: Cannot verify alignment with actual video/audio content
  • Content accuracy: Cannot check if captions correctly transcribe spoken words
  • Video-specific elements: Cannot analyze visual content that should be described
  • Context appropriateness: Cannot evaluate content-specific captioning decisions

Our analysis focuses on technical compliance and formatting standards that can be objectively measured from caption file data alone.

📚 Standards References & Documentation

Primary Standards Resources

Regulatory Framework