Amuta Space Talkers

A diarization viewer for Whisper transcription output, featuring a visual "space" display of speakers and waveform-based audio navigation.

Features

• Speaker visualization: Speakers displayed as animated orbs in a starfield
• Real-time transcription: Live transcript panel following audio playback
• Waveform navigation: Click/drag on the waveform to seek through the audio
• Keyboard controls: Space to play/pause, Arrow keys to seek

Quick Start

1. Place your audio file in input/
2. Place your Whisper transcript JSON in outputs/float32/
3. Generate the waveform data (see below)
4. Start a local server and open in browser:

   npx serve -p 5000
   

   Then navigate to http://localhost:5000

Waveform Generation

For optimal performance with long audio files (1-3 hours), waveform data is pre-generated as JSON rather than decoded in the browser.

Prerequisites

• Node.js (v14+)
• FFmpeg installed and available in PATH

Generate Waveform Data

node scripts/generate-waveform.js <input-audio> [output-json] [columns]

Arguments:

• input-audio - Path to the audio file (opus, mp3, wav, etc.)
• output-json - Output path for waveform JSON (default: <input>.waveform.json)
• columns - Number of waveform columns/peaks (default: 1000)

Example:

# Generate waveform for a single file
node scripts/generate-waveform.js input/amuta_2026-01-12_1.opus outputs/float32/amuta_2026-01-12_1.waveform.json

# Or let it auto-generate the output path
node scripts/generate-waveform.js input/meeting.opus

Waveform JSON Format

The generated JSON file has this structure:

{
  "version": 1,
  "source": "meeting.opus",
  "duration": 7200.5,
  "sampleRate": 48000,
  "columns": 1000,
  "peaks": [
    { "min": -0.82, "max": 0.91 },
    { "min": -0.45, "max": 0.52 }
  ]
}

Field	Description
version	Schema version for future compatibility
source	Original audio filename
duration	Audio duration in seconds
sampleRate	Original sample rate
columns	Number of data points
peaks	Array of min/max amplitude pairs

Configuration

Edit the paths at the top of app.js:

const transcriptPath = "outputs/float32/amuta_2026-01-12_1.json";
const waveformPath = "outputs/float32/amuta_2026-01-12_1.waveform.json";

Speaker Labels

Map speaker IDs to display names in app.js:

const SPEAKER_LABELS = {
  "SPEAKER_01": "Maya",
  "SPEAKER_02": "David",
};

Keyboard Shortcuts

Key	Action
Space	Play/Pause
← / A	Seek back 10 seconds
→ / D	Seek forward 10 seconds
Shift + ←/→	Seek 60 seconds

File Structure

amuta-meetings/
├── index.html              # Main HTML page
├── app.js                  # Application logic
├── styles.css              # Styles
├── scripts/
│   └── generate-waveform.js  # Waveform generator script
├── input/                  # Audio files (gitignored)
├── outputs/
│   └── float32/            # Transcript and waveform JSON
└── plans/
    └── waveform-optimization.md  # Architecture documentation

Performance Notes

• Waveform JSON (~20KB) loads in milliseconds vs decoding 50-100MB audio in 5-15 seconds
• The waveform is loaded immediately on page load for instant display
• Audio is only downloaded once (by the <audio> element)