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Machine Learning

Video Labeling for Machine Learning (2025 Guide)

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Averroes
Jul 23, 2025
Video Labeling for Machine Learning (2025 Guide)

Video labeling sits at the core of machine learning tasks that depend on movement, timing, and visual continuity. 

It’s the difference between a model that guesses and a model that understands sequences. 

But doing it well takes more than clicking through frames. You need smart annotation choices, scalable workflows, and tools that support video. 

We’ll cover the full process: what to label, how to label it, and how to keep quality high when the data gets big.

Key Notes

  • Video requires temporal awareness unlike static images.
  • There are 7 annotation types available: bounding boxes, polygons, segmentation, keypoints, 3D cuboids, tracking, events.
  • Automation through auto-tracking, interpolation, and active learning speeds up manual processes.
  • Handle edge cases like occlusions and blur with specialized marking and interpolation techniques.

What Makes Video Labeling Different from Image Annotation?

Video labeling involves annotating sequences of images, not just individual static frames. 

It requires temporal awareness (understanding how objects move, interact, appear, and disappear over time). 

Unlike single-image annotation, video annotation has to maintain object identity, handle occlusions, and capture actions as they unfold.

The data volume is also significantly higher. A 10-minute video at 30fps contains 18,000 frames. Annotating each of those frames manually is impractical without automation and frame sampling strategies.

Annotation Types in Video Labeling

Different ML tasks call for different annotation types. 

Here’s what to know:

  • Bounding Boxes: Standard for object detection and tracking. Ideal for vehicles, people, or machinery.
  • Polygons: Used for irregular object outlines (e.g., tools, wires). More accurate than boxes but more labor-intensive.
  • Semantic Segmentation: Pixel-level class labeling for high-precision tasks, such as road surface identification or defect detection.
  • Keypoints & Skeletons: Used in pose estimation and movement tracking, such as monitoring worker posture or facial recognition.
  • 3D Cuboids: Capture spatial depth. Common in autonomous driving and robotics.
  • Object Tracking: Maintain consistent labels across frames as objects move.
  • Event Annotation: Identify actions or sequences (e.g., a person dropping a tool or picking up a box).

Annotation types can be combined. 

For example, tracking a moving person with bounding boxes, while labeling the moment they wave as an event.

Ideal Workflow: From Raw Data to Validated Labels

1. Define Objectives and Labeling Schema 

Clarify what your model needs to learn – detection, classification, segmentation, etc. 

Build a detailed annotation guide with class definitions, edge case handling, and label examples.

2. Prepare and Organize Video Data 

Split videos into manageable chunks. Sample frames at consistent intervals (e.g., 1 every 5 frames). Use logical naming and timestamps to keep everything organized.

3. Pre-process and Plan Annotation Strategy 

Identify keyframes where motion or identity changes. Use interpolation for filler frames. Plan where automation can reduce manual effort without sacrificing quality.

4. Label Using Video-Optimized Tools 

Pick tools that support:

  • Video playback and frame navigation
  • Annotation copying or interpolation
  • Label versioning and review
  • Confidence thresholds for auto-labeling

5. Conduct Multi-layer QA 

Validate with model-assisted reviews and human checks. Incorporate annotator feedback. Use review dashboards to catch inconsistencies.

6. Iterate and Improve 

Feed labeled data into models. Use model output to flag edge cases and label gaps. Retrain and refine over time.

Tools That Make Video Labeling Work

V7 Darwin

A robust platform for high-speed, high-accuracy video annotation – ideal for large-scale projects and complex data. 

Built to handle segmentation, keypoint tracking, and multi-class labeling with ease.

Key Features:

  • Auto-track objects using pre-trained models
  • Keyframe interpolation across all annotation types
  • Timeline view with stacked annotation layers
  • API access for automation and MLOps integration
  • Frame rate control and scalable performance up to 100,000+ frames

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Supervisely

An enterprise-ready video annotation suite offering full video timeline control, powerful tracking tools, and collaborative project management.

Key Features:

  • Native browser-based video labeling without frame splitting
  • Multi-track timeline with precise navigation
  • AI-assisted object tracking and smart segmentation
  • Segment and frame tagging for event-level classification
  • Python SDK, plugin apps, and role-based access controls

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Dataloop

Optimized for precise, pixel-level video annotation and active learning workflows. Tailored for large datasets in automotive, retail, and robotics.

Key Features:

  • Keyframe-based interpolation with timeline visualization
  • Frame-accurate controls and object tracking
  • Occlusion toggles and label lifespan management
  • Collaborative tools for QA and review
  • Secure, scalable dataset management with audit logs

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Label Studio

An open-source, highly customizable platform supporting complex multi-modal data labeling, including video.

Key Features:

  • Object tracking with interpolated bounding boxes
  • Timeline segmentation for event labeling
  • New video UI with precise region controls
  • Customizable templates for any annotation use case
  • ML model integration and human-in-the-loop workflows

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SuperAnnotate

Enterprise-grade annotation suite built for speed, accuracy, and multi-modal projects.

Key Features:

  • Autotrack and interpolation for object motion tracking
  • Action detection and pose estimation tools
  • QA tools like benchmark scoring and gold-standard comparison
  • Cloud integration with AWS, GCP, Azure
  • Annotation toolset includes polygons, segmentation, keypoints

View Now

Labellerr

A cloud-native platform that balances automation and manual review with robust QA and secure enterprise controls.

Key Features:

  • Active learning and smart pre-labeling pipelines
  • Video interpolation and segment-based tracking
  • Plugin framework for custom annotation needs
  • AES-256 encrypted data and compliance features
  • Dashboard tracking, version control, and audit logs

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Automation & Human-in-the-Loop Workflows

Video annotation is time-consuming at scale. Automation speeds it up, but not at the cost of quality.

  • Auto-tracking uses ML models to follow objects frame to frame.
  • Interpolation generates in-between labels after annotating keyframes.
  • Pseudo-labeling lets pre-trained models label frames automatically.
  • Active learning focuses human attention on low-confidence or rare frames flagged by the model.

This hybrid model (machine assist + human validation) maximizes speed without sacrificing label consistency or accuracy.

Best Practices for Label Consistency and Quality

  • Establish detailed labeling guidelines and naming conventions
  • Train annotators using calibration sets and reference frames
  • Use timeline tools to manage label persistence across frames
  • Tag occlusions or uncertainties instead of deleting data
  • Maintain a feedback loop between annotation, review, and model performance

Edge Case Handling: Occlusions, Blur, and Lighting

Video data isn’t always clean. Real-world footage contains visual challenges:

Occlusions occur when objects are temporarily blocked by other elements. 

To preserve tracking:

  • Mark objects as occluded instead of deleting them
  • Interpolate movement before and after occlusion
  • Use object re-ID models to maintain identity

Motion Blur happens with fast movement or low frame rates. 

To address this:

  • Use approximate bounding boxes to maintain object continuity
  • Interpolate using nearby clear frames
  • Train models on blurred data to assist auto-labeling

Inconsistent Lighting from shadows, flickers, or camera exposure shifts can distort object boundaries. 

Solutions include:

  • Temporal smoothing across adjacent frames
  • Annotator training to handle lighting variation
  • Curating training data with lighting diversity

Scaling Video Labeling Projects

Scaling video labeling involves challenges across data, human effort, and tooling:

Data Volume: 

A single 30fps video can contain tens of thousands of frames. Frame sampling, clip segmentation, and keyframe selection are essential for manageable annotation.

Human Resources: 

Video labeling can take hundreds of hours per hour of footage. 

Train annotators thoroughly, use review cycles to ensure consistency, and adopt hybrid models (internal teams + vendors).

Tooling: 

Choose tools that offer automation, quality control, user roles, and scalability. Platforms should support annotation pipelines, API access, and model integrations for iteration.

Frequently Asked Questions

How do you choose the right frame rate for video labeling?

The ideal frame rate depends on how fast objects move and how often relevant changes occur. For high-motion scenes, annotate every 2–5 frames. For slower or static sequences, sampling every 10–15 frames may be sufficient.

What’s the difference between keyframe interpolation and object tracking?

Keyframe interpolation fills in annotations between two manually labeled frames. Object tracking uses AI to follow an object across multiple frames automatically, adjusting for scale, position, and motion patterns.

Can video labeling be done with synthetic data?

Yes, synthetic video data (especially in simulation environments) is increasingly used for model training and pre-annotation. It helps scale datasets, test edge cases, and reduce manual labeling workload.

What quality metrics should teams track during annotation?

Key metrics include inter-annotator agreement, label completeness, annotation latency, and model accuracy uplift after each dataset iteration. These help ensure consistent, scalable improvements.

Conclusion

Video labeling builds the foundation for machine learning models that need to understand how things move, interact, and change over time. 

Unlike image annotation, the process depends on temporal accuracy, consistent object tracking, and structured workflows that can scale with the data. The choice of annotation types, the way frames are sampled, and how teams balance automation with review all shape the quality of training data. 

And edge cases like blur, occlusion, and lighting shifts are part of the reality the model needs to learn from. The more intentional the labeling process, the more reliable the outcome. 

That’s what separates functional datasets from training data that performs.

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