Video Quality Comparison: Compression, Upscaling, and Codec Guide

Understanding video quality requires more than just looking at resolution numbers. Codec efficiency, compression artifacts, and processing quality all affect what you see on screen. In this technical guide, we'll cover how to properly compare video quality across different encoding scenarios.

Video Quality Fundamentals

What Determines Video Quality?

Several factors contribute to perceived video quality:

• Resolution - Pixel dimensions (1080p, 4K, etc.)
• Bitrate - Data per second (higher = more detail)
• Codec efficiency - How well data is compressed
• Frame rate - Frames per second (24, 30, 60 fps)
• Color depth - Bits per color channel (8-bit, 10-bit)
• Chroma subsampling - Color information ratio (4:4:4, 4:2:0)

Common Quality Issues

• Blocking - Visible squares, especially in motion
• Banding - Stair-step gradients in smooth areas
• Mosquito noise - Shimmer around edges
• Blurring - Loss of fine detail
• Color shifts - Inaccurate color reproduction
• Temporal artifacts - Flickering or stuttering

Codec Comparison

Modern video codecs offer different tradeoffs between quality, file size, and compatibility:

H.264 vs H.265 Comparison

H.265 typically achieves the same quality as H.264 at 40-50% lower bitrate. When comparing:

• Test at equivalent bitrates to see quality difference
• Test at equivalent file sizes to see efficiency
• Focus on complex scenes with motion and detail

AV1: The New Standard

AV1 offers approximately 30% better compression than H.265. Compare AV1 when:

• Targeting modern browsers and devices
• File size is critical (streaming)
• Encode time is not a constraint

How to Compare Video Quality

Visual Comparison

The most important test is what you can see. Use a comparison tool with:

• Synchronized playback - Both videos play together
• Frame-by-frame stepping - Examine individual frames
• Zoom capability - Inspect fine details
• Difference view - Highlight pixel differences

Objective Metrics

Quantitative metrics supplement visual comparison:

• PSNR - Peak Signal-to-Noise Ratio (higher = better)
• SSIM - Structural Similarity Index (closer to 1 = better)
• VMAF - Netflix's perceptual quality metric (0-100)

What to Look For

Focus on challenging content when comparing:

• High motion scenes - Action, sports, fast camera movement
• Fine detail - Hair, fabric texture, foliage
• Gradients - Skies, studio backgrounds
• Dark scenes - Shadow detail and banding
• Text and graphics - Sharp edges

Compression Level Comparison

Understanding Bitrate

Bitrate determines how much data is used per second. Compare identical encodes at different bitrates to find the optimal quality/size tradeoff.

CRF/CQ Comparison

Constant Rate Factor (CRF) targets consistent quality. Compare different CRF values:

• CRF 18-20 - Visually lossless for most content
• CRF 21-23 - High quality, smaller files
• CRF 24-28 - Good quality, significant compression

Finding the Sweet Spot

Create comparison encodes at multiple quality levels. The point where you can no longer see improvement is your optimal setting.

Upscaling Quality Comparison

Traditional vs AI Upscaling

AI upscalers like Topaz Video AI, Real-ESRGAN, and others produce dramatically better results than traditional methods. Compare:

• Bicubic interpolation (baseline)
• Lanczos resampling
• AI-based upscaling

What to Compare in Upscaled Video

• Edge sharpness - Clean lines without halos
• Texture preservation - Natural detail, not artificial
• Artifact introduction - AI can add fake detail
• Temporal consistency - No flickering between frames

Comparing Upscaler Settings

Most AI upscalers have multiple models and settings. Create comparison videos with different configurations to find the best for your content type.

Frame Interpolation Comparison

Evaluating Interpolated Frames

Frame interpolation (24fps to 60fps) can introduce artifacts. Compare:

• Original footage at native frame rate
• Interpolated footage at target frame rate
• Focus on high-motion scenes and edges

Common Interpolation Issues

• Ghosting - Transparent duplicates of moving objects
• Morphing - Unnatural object deformation
• Edge artifacts - Shimmer or distortion at boundaries

Practical Comparison Workflow

Step 1: Prepare Test Content

Select clips that represent challenging content: action scenes, gradients, fine detail, and typical footage.

Step 2: Create Comparison Encodes

Encode the same source with different settings, changing only one variable at a time.

Step 3: Use Proper Comparison Tools

Load both videos into a comparison tool with synchronized playback. DualView provides:

• Frame-accurate sync
• Multiple comparison modes
• Zoom for detail inspection
• Export for documentation

Step 4: Systematic Evaluation

Evaluate systematically rather than randomly scrubbing. Check specific challenging moments and step through frame-by-frame in critical areas.

Step 5: Document Results

Record your findings including encoding settings, file sizes, and quality observations. Export comparison screenshots or videos for reference.

Quality Metrics Deep Dive

PSNR (Peak Signal-to-Noise Ratio)

Measures pixel-level difference. Simple but doesn't correlate well with perceived quality. Useful for lossless comparisons.

SSIM (Structural Similarity Index)

Considers structure, luminance, and contrast. Better correlation with human perception than PSNR.

VMAF (Video Multimethod Assessment Fusion)

Netflix's machine learning metric trained on human quality ratings. Currently the best predictor of perceived quality.

Using Metrics with Visual Comparison

Metrics complement but don't replace visual comparison. Use them to:

• Automate large-scale comparisons
• Quantify differences
• Track quality across many encodes

Common Comparison Mistakes

• Judging on compressed previews - Always compare at full resolution
• Different display settings - Calibrate monitors and use consistent viewing conditions
• Ignoring temporal artifacts - Static frames don't show motion issues
• Confirmation bias - Blind testing removes expectation effects
• Insufficient test content - Use diverse, challenging material

Conclusion

Proper video quality comparison requires the right tools, methodology, and understanding of what to look for. Whether you're comparing codecs, compression levels, or processing results, systematic comparison ensures you make informed decisions about quality tradeoffs.

Combine visual comparison with objective metrics for the most complete picture. And always test on content that represents your actual use case - a setting that works for animation might not work for live action, and vice versa.