# Forge Audio Pool

> Add fire-and-forget audio playback with a source pool and volume fading for click-free start/stop transitions.

- **Type:** Skill
- **Install:** `agentstack add skill-nebulavenus-forge-gpu-forge-audio-pool`
- **Verified:** Yes — security-reviewed for prompt injection and unsafe behavior
- **Seller:** [Nebulavenus](https://agentstack.voostack.com/s/nebulavenus)
- **Installs:** 0
- **Category:** [Content & Media](https://agentstack.voostack.com/c/content-and-media)
- **Latest version:** 0.1.0
- **License:** Zlib
- **Upstream author:** [Nebulavenus](https://github.com/Nebulavenus)
- **Source:** https://github.com/Nebulavenus/forge-gpu/tree/main/.claude/skills/forge-audio-pool

## Install

```sh
agentstack add skill-nebulavenus-forge-gpu-forge-audio-pool
```

Requires the [AgentStack CLI](https://agentstack.voostack.com/docs/cli). Works with Claude Code, Cursor, and any MCP-compatible agent.

## About

# forge-audio-pool

Add fire-and-forget sound effect playback using `ForgeAudioPool` and smooth
volume transitions using the fade envelope on `ForgeAudioSource`. Based on
[Audio Lesson 02](../../../lessons/audio/02-sound-effects/).

## When to use

- Playing the same sound multiple times with overlap (polyphony)
- One-shot sound effects that should auto-clean-up when finished
- Starting or stopping sounds without audible clicks (fade-in / fade-out)
- Ambient loops that toggle smoothly with a volume ramp

## Source pool pattern

```c
#include "audio/forge_audio.h"

/* In app_state */
ForgeAudioPool pool;
ForgeAudioBuffer sfx_buffer;

/* In SDL_AppInit */
forge_audio_pool_init(&pool);
forge_audio_load_wav("assets/audio/impact.wav", &sfx_buffer);

/* Fire-and-forget: each call allocates a new slot (up to 32) */
int slot = forge_audio_pool_play(&pool, &sfx_buffer, 1.0f, false);
if (slot = 0) {
    ForgeAudioSource *src = forge_audio_pool_get(&pool, slot);
    forge_audio_source_fade_in(src, 0.3f);
}

/* Update fades on all pool sources each frame */
for (int i = 0; i < FORGE_AUDIO_POOL_MAX_SOURCES; i++) {
    if (pool.sources[i].playing) {
        forge_audio_source_fade_update(&pool.sources[i], dt);
    }
}
```

## Ambient loop with fade toggle

For a single looping source managed outside the pool (direct fade control):

```c
/* In app_state */
ForgeAudioSource ambient;
bool ambient_active;

/* Toggle on key press */
if (ambient_active) {
    forge_audio_source_fade_out(&ambient, fade_duration);
    ambient_active = false;
} else {
    if (!ambient.playing) forge_audio_source_reset(&ambient);
    forge_audio_source_fade_in(&ambient, fade_duration);
    ambient_active = true;
}
```

## Common mistakes

- **Forgetting `fade_update`** — The fade does not advance automatically.
  Call `forge_audio_source_fade_update(src, dt)` once per frame for every
  source that might be fading.
- **Calling fade_update per mix call** — Call it per frame, not per mix
  invocation. The rate is in units per second, scaled by `dt`.
- **Not zeroing the mix buffer** — `forge_audio_pool_mix()` is additive.
  Always `memset(out, 0, ...)` before the first mix call each frame.
- **Ignoring pool_play return value** — Returns -1 when full. Decide whether
  to drop the sound or steal an existing slot.

## API reference

| Function | Purpose |
|---|---|
| `forge_audio_pool_init` | Zero all 32 slots |
| `forge_audio_pool_play` | Play buffer in first idle slot → index or -1 |
| `forge_audio_pool_get` | Get source pointer at index → `ForgeAudioSource*` or NULL |
| `forge_audio_pool_mix` | Mix active sources, reclaim finished |
| `forge_audio_pool_stop_all` | Stop everything |
| `forge_audio_pool_active_count` | Count of playing sources |
| `forge_audio_source_fade` | Start fade toward target over duration |
| `forge_audio_source_fade_in` | 0→1 fade, starts playback |
| `forge_audio_source_fade_out` | Current→0 fade, auto-stops |
| `forge_audio_source_fade_update` | Advance fade by dt seconds |

## Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

- **Author:** [Nebulavenus](https://github.com/Nebulavenus)
- **Source:** [Nebulavenus/forge-gpu](https://github.com/Nebulavenus/forge-gpu)
- **License:** Zlib

Install and usage instructions live in the source repository linked above.

## Pricing

- **Free** — Free

## Security capabilities

Automated source analysis of v0.1.0 — what this tool can access:

- **Network access:** no
- **Filesystem access:** no
- **Shell / process execution:** no
- **Environment & secrets:** no
- **Dynamic code execution:** no

*"Yes" means the capability is present in the source — more access means more to trust, not that it is unsafe.*


## Versions

- **0.1.0** — security scan: passed — Imported from the upstream source.

## Links

- Listing page: https://agentstack.voostack.com/l/skill-nebulavenus-forge-gpu-forge-audio-pool
- Seller: https://agentstack.voostack.com/s/nebulavenus
- Browse the marketplace: https://agentstack.voostack.com/browse

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