Audio Output

Dual-Output Architecture

The app plays audio simultaneously to two independent output devices:

graph LR
    subgraph TTS Engine
        A[Audio Buffer]
    end
    A --> B[Monitor Output]
    A --> C[Secondary Output]
    B --> D[Headphones/Speakers]
    C --> E[Virtual Cable Input]
    E --> F[Voice App Mic Input]

Monitor Output

The primary output device — typically your headphones or speakers. This is where you hear the speech.

Secondary Output

The virtual audio cable input. Voice applications (Discord, VRChat) use this as their microphone input.

Volume Controls

Independent volume sliders for each output:

• Monitor Volume: 0–100% (default: 100%)
• Secondary Volume: 0–100% (default: 100%)

Volumes are applied as float multipliers (0.0–1.0) to the NAudio WasapiOut stream.

Device Selection

In Settings → Audio:

1. Monitor Output dropdown — lists all active WASAPI render devices
2. Secondary Output dropdown — lists all active WASAPI render devices
3. Refresh button — re-enumerates devices (useful after plugging/unplugging)

Test Buttons

Three test buttons help verify your audio setup:

Trailing Silence Trimming

When enabled, the app automatically removes trailing silence from generated TTS audio:

• Trim Trailing Silence: Enable/disable the feature
• Silence Retention: What percentage of trailing silence to keep (5–100%)
  • 5% = almost all silence removed (fastest turnaround)
  • 100% = no trimming (default)

How It Works

1. After TTS synthesis, the raw 16-bit PCM data is scanned backwards from the end
2. Frames where all samples are below the silence threshold (~0.5% of max amplitude) are identified
3. The specified fraction of trailing silence is retained
4. The trimmed audio is passed to the audio router

Audio Format

Playback State

The PlaybackState singleton tracks:

• IsPlaying — whether audio is currently playing
• CurrentText — the text being spoken
• PlaybackDurationSeconds — total audio duration
• PlaybackStartedUtc — when playback began

This state is shared between the overlay and phrase playback, ensuring the playback timer and status display are consistent.