Video Transcription & Subtitles

Turn lectures, training videos, and podcasts into accurate text transcripts and synchronized subtitle files — automatically. Upload a recording and receive ready-to-use SRT and VTT subtitles, even for hours-long content in Finnish or other languages.

Why It Matters

• Accessibility — Subtitles make video content accessible to hearing-impaired audiences and non-native speakers
• Searchability — Once transcribed, every word in a video becomes searchable (see Semantic Video Search)
• Time savings — Manual transcription takes 4–6x the audio duration; this pipeline processes content in a fraction of the time
• Compliance — Many institutions require captioned video content for accessibility regulations

How It Works

1. Audio is split into chunks — Large files are divided into overlapping segments (~20 minutes each) for parallel processing
2. Each chunk is transcribed — Multiple chunks run simultaneously using Azure OpenAI Whisper, cutting total processing time significantly
3. Results are merged — Overlapping regions are deduplicated to produce seamless, continuous output
4. Optional: Enhancement — A language model corrects domain-specific terminology and formatting
5. Optional: Translation — Content can be translated while preserving original timestamps

Key Features

• Parallel processing — Handles a 2-hour lecture in a fraction of sequential time by transcribing 3+ chunks simultaneously
• Large file support — No practical limit on audio duration; files are automatically chunked and reassembled
• Multiple output formats — SRT subtitle files (with timestamps), VTT subtitles, and plain text transcripts
• Finnish and multilingual — Works with Finnish, Swedish, English, and other languages supported by Whisper
• Speaker diarization — Optional GPT-4o Transcribe model identifies who is speaking
• Overlap deduplication — 15-second overlaps between chunks avoid cutting words mid-sentence

Software Component

pip install gaik[parallel-transcriber]

The ParallelTranscriber class handles chunking, transcription, merging, and output — all configured through a simple TranscriptionConfig object. Requires ffmpeg for audio processing.

Related Resources