Lodown

Converts lecture audio recordings into searchable text using automatic speech recognition (ASR) models, likely leveraging cloud-based transcription APIs (Whisper, Google Speech-to-Text, or similar) with speaker diarization to attribute segments to different speakers. The system processes uploaded audio files, segments them by speaker turns, and outputs timestamped transcripts that preserve temporal context for navigation back to source material.

Indexes transcribed lecture text using vector embeddings (likely sentence-level or paragraph-level embeddings from models like OpenAI's text-embedding-3 or similar) to enable semantic search beyond keyword matching. Users can query lectures with natural language questions, and the system returns relevant transcript segments ranked by semantic similarity, with direct links back to the original audio timestamp for playback.

Parses transcripts to automatically detect lecture structure (topics, subtopics, key points) using heuristics or fine-tuned language models, then generates hierarchical outlines or structured notes. The system identifies topic boundaries (often marked by speaker transitions, silence, or linguistic cues like 'next topic'), extracts key sentences, and organizes them into a study-friendly format with optional formatting (bullet points, headers, emphasis on definitions).

Provides a file upload interface (web or mobile) that accepts lecture recordings, stores them in cloud object storage (likely AWS S3, Google Cloud Storage, or similar), and manages file metadata (upload date, course, instructor, duration). The system handles file validation, virus scanning, and access control to ensure only the uploading user can access their recordings. Supports batch uploads and file organization by course or semester.

Maintains precise timestamp mappings between transcript segments and audio playback positions, enabling click-to-play functionality where users can click any transcript line and jump to that moment in the audio. The system uses ASR output timestamps (typically accurate to 100-500ms) and provides an embedded audio player synchronized with transcript highlighting, showing which segment is currently playing.

Allows users to tag lectures with course name, instructor, date, topic, and custom labels, then organize and filter lectures by these metadata fields. The system provides a dashboard or list view where users can browse lectures by course, sort by date, and search by tags. Metadata is stored in a relational database and indexed for fast filtering and retrieval.

Implements a freemium business model where users get limited free access (likely 5-10 hours of transcription per month, basic search, limited storage) with in-app prompts encouraging upgrade to paid tiers for higher limits. The system tracks usage metrics (transcription minutes, storage used, searches performed) and gates premium features (advanced search, offline access, priority processing) behind subscription paywall.

Allows users to download transcripts and generated notes in various formats (PDF, Markdown, plain text, DOCX) for use in external tools (Word, Notion, Obsidian, etc.). The system preserves formatting (headers, bullet points, timestamps) during export and optionally includes metadata (course, date, instructor) in the exported file.

Provides iOS and Android apps allowing users to download transcripts and notes for offline access, enabling study on-the-go without internet connectivity. The app syncs with the cloud backend when online and caches transcripts locally. Users can search and read transcripts offline, though audio playback and transcription processing require internet.