FFmpeg Errors

Issues with FFmpeg audio capture and device enumeration.

Symptoms

• "FFmpeg not found" error
• "Failed to start audio capture" message
• Audio devices not listed
• Silent audio levels despite speaking
• FFmpeg error in logs

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Common Errors

Error: FFmpeg Not Found

Message:

Failed to start audio capture: FFmpeg not found

Windows Solutions:

1. Reinstall Intervu — Bundled FFmpeg downloads during installation
2. Use system FFmpeg — Set custom path in Settings → Advanced → FFmpeg Path

macOS Solutions:

1. Install FFmpeg via Homebrew — FFmpeg is not bundled on macOS

brew install ffmpeg

2. Verify installation:

ffmpeg -version

3. Set custom path if needed — In Settings → Advanced → FFmpeg Path:
   • Intel Macs: /usr/local/bin/ffmpeg
   • Apple Silicon Macs: /opt/homebrew/bin/ffmpeg

Error: Device Not Found

Windows Message:

[dshow] Could not find device "CABLE Output"

Causes:

• VB-Cable not installed
• Device name changed
• Windows audio system needs refresh

Solutions:

1. Install VB-Cable (see No Audio Devices)
2. Reboot
3. Check exact device name in Windows Sound Settings

macOS Message:

[avfoundation] Could not find device ":0"

Causes:

• FFmpeg not installed or lacks AVFoundation
• Microphone permission not granted
• Device disconnected

Solutions:

1. Install FFmpeg: brew install ffmpeg
2. Grant microphone permission in System Settings → Privacy & Security
3. Reconnect audio device
4. Click Refresh Devices in Intervu Settings

Error: Permission Denied

Windows Message:

Permission denied when accessing microphone

Solutions:

1. Open Settings → Privacy → Microphone
2. Enable microphone access for apps
3. Enable microphone access for desktop apps
4. Restart Intervu

macOS Message:

Microphone permission not granted

Solutions:

1. Open System Settings → Privacy & Security → Microphone
2. Enable Intervu
3. If not listed, open Intervu and click the microphone button to trigger the permission prompt
4. Restart Intervu

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Bundled FFmpeg (Windows Only)

How It Works

Intervu bundles a custom FFmpeg build from gyan.dev on Windows:

1. During npm install, scripts/download-ffmpeg.js runs
2. Downloads FFmpeg to %LOCALAPPDATA%/intervu/ffmpeg.exe
3. ~214MB download

Checking Bundled FFmpeg

# Check if FFmpeg exists
dir %LOCALAPPDATA%\intervu\ffmpeg.exe

# Check file size (should be ~200MB)
# If much smaller, download failed

Re-downloading FFmpeg

If the bundled FFmpeg is corrupted:

# Navigate to Intervu directory
cd %LOCALAPPDATA%\intervu

# Delete corrupted file
del ffmpeg.exe

# Reinstall Intervu or manually download

macOS Users

FFmpeg is not bundled on macOS. You must install it manually via Homebrew: brew install ffmpeg

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Using System FFmpeg

If bundled FFmpeg doesn't work, use system FFmpeg.

Windows: Installing FFmpeg System-Wide

1. Download from ffmpeg.org
2. Extract to C:\ffmpeg
3. Add C:\ffmpeg\bin to PATH

macOS: Installing FFmpeg

brew install ffmpeg

Configuring in Intervu

1. Open Settings (gear icon)
2. Go to Advanced Settings
3. Set FFmpeg Path to your FFmpeg executable:
   • Windows: C:\ffmpeg\bin\ffmpeg.exe
   • macOS (Intel): /usr/local/bin/ffmpeg
   • macOS (Apple Silicon): /opt/homebrew/bin/ffmpeg
4. Restart Intervu

Required FFmpeg Build

Intervu requires FFmpeg with platform-specific audio support:

• Windows: Use "full" build from gyan.dev with DirectShow support (not "essentials" or "shared")
• macOS: Homebrew FFmpeg includes AVFoundation support by default
• Linux: Install ffmpeg package with libavdevice

Platform Audio Support

• Windows: Standard FFmpeg builds may not include DirectShow. Use the full gyan.dev build.
• macOS: Homebrew's FFmpeg includes AVFoundation. Other builds may lack it.

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FFmpeg Logs

Viewing FFmpeg Output

1. Open Settings (gear icon)
2. Click Open Logs Folder
3. Open app.log
4. Look for lines starting with [ffmpeg]

Common Log Messages

Windows — Successful start:

[ffmpeg] Starting audio capture: dshow://Audio=CABLE Output
[ffmpeg] Audio capture started

macOS — Successful start:

[ffmpeg] Starting audio capture: :0
[ffmpeg] Audio capture started

Windows — Device enumeration:

[ffmpeg] Listing devices...
[ffmpeg] Found device: CABLE Output
[ffmpeg] Found device: Microphone (USB)

macOS — Device enumeration:

[ffmpeg] listing AVFoundation devices...
[ffmpeg] Found device: MacBook Pro Microphone
[ffmpeg] Found device: BlackHole 2ch

Error messages:

[ffmpeg] Error: Could not open inputfile
[ffmpeg] Error: Device not found
[ffmpeg] Error: Permission denied

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Performance Issues

High CPU Usage

FFmpeg audio capture is CPU-light (~1-2%). If you see higher:

1. Check audio chunk duration (increase to reduce API calls)
2. Lower sample rate if possible
3. Close unnecessary applications

Audio Delay

Audio should be near real-time. If delayed:

1. Reduce audio chunk duration in Advanced Settings
2. Check system resources
3. Ensure GPU is being used for STT/LLM

Buffer Overflow

[ffmpeg] Buffer overflow, dropping packets

Causes:

• System can't process audio fast enough
• Network latency to STT endpoint

Solutions:

• Increase audio chunk duration
• Use local STT endpoint
• Close unnecessary applications

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Alternative Audio Capture

If FFmpeg continues to have issues, consider:

VB-Cable Recording (Windows)

Some users record directly from VB-Cable using OBS or Audacity, then use the file with Intervu's manual mode (if available in future versions).

Hardware Loopback

Some audio interfaces support loopback recording, bypassing the need for VB-Cable.

BlackHole + Multi-Output (macOS)

On macOS, use BlackHole with a multi-output device. See macOS Setup Guide for detailed instructions.

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Still Not Working?

Windows: Complete Reset

# Close Intervu
# Delete all Intervu data
rmdir /s /q %APPDATA%\intervu
rmdir /s /q %LOCALAPPDATA%\intervu

# Reinstall Intervu
# Reconfigure from scratch

macOS: Complete Reset

# Close Intervu
# Delete settings
rm -rf ~/Library/Application\ Support/intervu

# Reinstall FFmpeg if needed
brew reinstall ffmpeg

# Restart Intervu
# Reconfigure from scratch

Check Platform Version

Windows:

Intervu requires Windows 10 or later. Check your version:

winver

macOS:

Intervu requires macOS 12 (Monterey) or later. Check your version:

sw_vers

Check Audio Drivers

Windows:

1. Open Device Manager
2. Expand Sound, video and game controllers
3. Check for warning icons
4. Update drivers if needed

macOS:

Audio drivers are managed by the system. If you have issues:

1. Reset Core Audio: sudo killall coreaudiod
2. Check for macOS updates
3. Verify BlackHole is installed correctly

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Next Steps

• No Audio Devices — Device enumeration issues
• macOS Troubleshooting — macOS-specific issues
• Audio Devices — Audio configuration