Voice Interview System

A comprehensive voice-enabled interview demonstration showcasing PromptKit’s stage-based pipeline architecture with support for streaming, VAD, TTS, and ASM-based models.

Features

• Dual Audio Modes

  • ASM Mode: Native bidirectional audio streaming with Gemini 2.0 (continuous, real-time)
  • VAD Mode: Voice Activity Detection with turn-based processing and TTS output

• Stage-Based Pipeline Architecture

  • Demonstrates the full power of PromptKit’s streaming pipeline
  • Real-time audio processing through pipeline stages
  • Seamless integration with multiple provider modes

• Multiple Interview Topics

  • Classic Rock Music
  • Space Exploration
  • Programming & Computer Science
  • World History
  • Movies & Cinema

• Optional Webcam Integration

  • Send periodic webcam frames for multimodal context
  • Visual engagement analysis

• Rich Terminal UI

  • Real-time audio level visualization
  • Progress tracking with score display
  • Live transcript display
  • Beautiful, interactive interface using Bubbletea

Requirements

System Dependencies

# macOS
brew install portaudio ffmpeg

# Ubuntu/Debian
sudo apt-get install portaudio19-dev ffmpeg

# Windows
# Download PortAudio from http://www.portaudio.com/
# Download ffmpeg from https://ffmpeg.org/download.html

Environment

export GEMINI_API_KEY=your_api_key_here

Quick Start

# Navigate to the example directory
cd sdk/examples/voice-interview

# Run with default settings (ASM mode, Classic Rock topic)
go run .

# Run with a specific topic
go run . --topic programming

# Run in VAD mode (turn-based with TTS)
go run . --mode vad --topic space

# Enable webcam for visual context
go run . --webcam --topic movies

# List all available topics
go run . --list-topics

Command-Line Options

Flag	Default	Description
--mode	asm	Audio mode: asm (native audio) or vad (turn-based with TTS)
--topic	classic-rock	Interview topic (see --list-topics)
--webcam	false	Enable webcam for visual context
--pack	./interview.pack.json	Path to PromptPack file
--no-ui	false	Disable rich terminal UI
--verbose	false	Enable verbose logging
--list-topics	-	List available interview topics and exit

Architecture

Pipeline Stages

This example demonstrates the stage-based pipeline architecture:

┌─────────────────────────────────────────────────────────────────┐
│                    Voice Interview Pipeline                      │
├─────────────────────────────────────────────────────────────────┤
│                                                                  │
│  ┌──────────────┐    ┌──────────────┐    ┌──────────────┐       │
│  │   Audio      │    │   VAD        │    │  Provider    │       │
│  │   Capture    │───▶│   Stage      │───▶│   Stage      │       │
│  │   Stage      │    │ (if VAD mode)│    │ (ASM/Text)   │       │
│  └──────────────┘    └──────────────┘    └──────────────┘       │
│         │                                        │               │
│         │                                        ▼               │
│         │            ┌──────────────┐    ┌──────────────┐       │
│         │            │   TTS        │◀───│  Response    │       │
│         │            │   Stage      │    │  Processing  │       │
│         │            │ (if VAD mode)│    │              │       │
│         │            └──────────────┘    └──────────────┘       │
│         │                   │                                    │
│         ▼                   ▼                                    │
│  ┌──────────────────────────────────────────────────────┐       │
│  │                  Audio Playback                       │       │
│  └──────────────────────────────────────────────────────┘       │
│                                                                  │
└─────────────────────────────────────────────────────────────────┘

ASM Mode (Audio Streaming Model)

In ASM mode, the pipeline uses native bidirectional audio streaming:

• Continuous streaming: Audio flows continuously in both directions
• No turn detection needed: The model handles conversation flow
• Lower latency: Real-time response without waiting for turn boundaries
• Requires: Gemini 2.0 Flash Exp or similar ASM-capable models

VAD Mode (Voice Activity Detection)

In VAD mode, the pipeline uses turn-based processing:

• Turn detection: VAD stage detects speech/silence boundaries
• Accumulation: Speech is accumulated until silence detected
• TTS output: Text responses are converted to speech
• Works with: Any text-based LLM + TTS service

Project Structure

voice-interview/
├── main.go                 # Entry point with mode selection
├── interview.pack.json     # PromptPack configuration
├── README.md              # This file
├── audio/
│   └── portaudio.go       # Audio capture/playback
├── video/
│   └── webcam.go          # Webcam capture (optional)
├── interview/
│   ├── controller.go      # Interview orchestration
│   ├── state.go           # State management
│   └── questions.go       # Question banks
└── ui/
    └── app.go             # Bubbletea terminal UI

Customization

Adding New Topics

Edit interview/questions.go to add new question banks:

func myCustomQuestions() *QuestionBank {
    return &QuestionBank{
        Topic:       "My Custom Topic",
        Description: "Description of the topic",
        Questions: []Question{
            {
                ID:       "custom-1",
                Text:     "Your question here?",
                Answer:   "Expected answer",
                Hint:     "Optional hint",
                Category: "category",
            },
            // Add more questions...
        },
    }
}

Then register it in GetQuestionBank().

Modifying the Interview Flow

The interview behavior is defined in interview.pack.json. Modify the system template to change:

• Interviewer personality
• Scoring guidelines
• Feedback style
• Response format

Custom Audio Configuration

Adjust audio settings in audio/portaudio.go:

const (
    InputSampleRate       = 16000  // Microphone sample rate
    OutputSampleRate      = 24000  // Speaker sample rate
    Channels              = 1      // Mono audio
    InputFramesPerBuffer  = 1600   // 100ms chunks
    EnergyThreshold       = 500    // VAD sensitivity
)

Troubleshooting

No Audio Input

1. Check microphone permissions in system settings
2. Verify PortAudio installation: brew info portaudio
3. List audio devices: The app will show available devices on startup

Webcam Not Working

1. Ensure ffmpeg is installed: ffmpeg -version
2. Check camera permissions
3. Try a different device index: The app uses device 0 by default

API Errors

1. Verify GEMINI_API_KEY is set correctly
2. Check API quota and rate limits
3. Ensure you have access to the required models:
   • ASM mode: gemini-2.0-flash-exp
   • VAD mode: gemini-2.5-flash

UI Display Issues

Run with --no-ui flag for simple terminal output if the rich UI doesn’t render correctly.

Example Session

╔══════════════════════════════════════════════════════════════╗
║         🎤 Voice Interview System - PromptKit Demo           ║
╠══════════════════════════════════════════════════════════════╣
║  Topic: Classic Rock Music                                   ║
║  Mode:  ASM (Native Audio)                                   ║
║  Questions: 5                                                ║
╠══════════════════════════════════════════════════════════════╣
║  Controls:                                                   ║
║    • Speak naturally into your microphone                    ║
║    • Press Ctrl+C to end the interview                       ║
╚══════════════════════════════════════════════════════════════╝

🎤 [████████████████░░░░░░░░░░░░░░] 53%

Question 1 of 5
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
Q1: Which band released the album 'Dark Side of the Moon' in 1973?

🤖 That's correct! Pink Floyd released this iconic album...
👤 Pink Floyd

Score: 10/50  │  Progress: 20%

Related Examples

• duplex-streaming - Basic duplex streaming example
• streaming - Text streaming example
• multimodal - Image/audio input example

License

This example is part of PromptKit and is available under the same license.