GAIKSemantic Video Search
Find the exact moment in a video by describing what you're looking for
Semantic Video Search
Find the exact moment in a lecture where a topic is discussed — just by typing a question in plain language. The system searches across an entire video library and returns timestamped results, so you can jump directly to the relevant segment.
Try the Live Demo: gaik-demo.2.rahtiapp.fi/video-search
Search across 11 indexed lecture videos with 300+ segments. Try queries like "tekoäly työelämässä" or "kielitaito".
Why It Matters
- Instant access — Skip scrubbing through hours of video to find the 30 seconds you need
- Natural language — Search by meaning, not just exact keywords. "How does AI affect jobs?" finds segments about "tekoälyn vaikutus työelämään"
- Builds on transcription — Any video that has been transcribed and subtitled can be made searchable
- Scales effortlessly — Works across 1 video or 1,000 videos with the same search interface
How It Works
- Subtitles are split into segments — Each video's subtitles are grouped into ~30–60 second chunks
- Each segment gets a numerical fingerprint — An AI model converts the text into a vector embedding that captures its meaning
- Search combines meaning and keywords — When you type a query, the system finds segments that are both semantically similar and contain matching terms
Search Methods
The demo offers three search modes:
| Mode | Best for | How it works |
|---|---|---|
| Hybrid (default) | Everyday use | Combines AI meaning + keyword matching using Reciprocal Rank Fusion. Most reliable for general queries. |
| AI meaning | When you don't remember exact words | Finds results by meaning — "tooth replacement" also finds "dental implants" or "prosthetics". |
| Exact words | Specific terms or names | Classic keyword search — finds the exact words you type. |
Finnish Language Support
Finnish is an agglutinative language — words change form based on grammar (e.g. "xylitol" becomes "xylitolin", "xylitolia", "xylitolista"). Standard keyword search would miss these forms.
The system uses prefix matching so "xylitol" automatically matches all Finnish inflections. Combined with trigram similarity as a fallback, it handles typos and word variations gracefully.
Precise Timestamp Seeking
Each 30–60 second segment is backed by individual subtitle lines (2–5 seconds each). When a search result is selected, the system resolves the exact subtitle line within the segment, achieving ~3–5 second precision for video playback.
Getting Started
The database schema and search functions are provided as ready-to-use SQL migration scripts:
- Start a PostgreSQL database with the pgvector extension
- Run the 5 SQL migration files in order to create the schema, indexes, and search functions
- Insert video segments with embeddings from your AI model
- Call the
hybrid_search()function to search
Related Resources
| Resource | Link |
|---|---|
| Video search SQL scripts | GitHub |
| PgVectorStore Python component | GitHub |
| PgVectorStore README (setup guide) | GitHub |
| Live Demo | video-search |