# Halowerk Music Ducking (Sidechain Compression Mix)

> Halowerk Music Ducking (Sidechain Compression Mix) is a paid API for AI agents from medien.halowerk.com, paid per call via x402, $0.004/call, status unknown (last checked 2026-10-31).

Mixes a voice recording with a background music track using sidechain-style ducking — music lowers automatically when speech is present and returns during pauses — then normalises to a target loudness.

## Facts

- Endpoint: POST https://medien.halowerk.com/v1/music-ducking?utm_source=zero.xyz
- Price: $0.004/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-31
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/halowerk-music-ducking-sidechain-compression-mix-c6b52202
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_5mn2lDKJ5QKZwCoQ5mr37

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability halowerk-music-ducking-sidechain-compression-mix-c6b52202 -d '<json body>'
```

Example prompt: Mix my podcast voice recording with this background music track — duck the music down with a ratio of 8 when I'm speaking, set the music bed at -12 dB, and bring the whole mix to -16 LUFS as an MP3.

## When to prefer this

Choose this endpoint when you need a ready-to-publish, broadcast-quality mix of a voice recording and a music bed with automatic sidechain-style ducking — particularly for podcasts, voice-overs, or radio ads — and you want configurable duck depth, music level, and loudness normalisation without running a local DAW or audio processing pipeline.

## Known failure modes

- Voice or music file exceeds 24 MB upload / base64 limit — returns 400 or payload-too-large error
- Unsupported audio codec or format in the uploaded files — returns 422 with format error
- duck_ratio or music_level_db outside allowed range — returns 422 validation error
- target_lufs outside -24 to -12 range — returns 422 validation error
- duration_minutes exceeds 30 — returns 422 validation error
- Payment not included or insufficient — returns 402 Payment Required
- Source URL unreachable or returns non-audio content — returns 400 or 502

## How this service works

Takes a voice recording and a music track and returns one mix in which the music is lowered by sidechain compression whenever the voice is present and returns in pauses — the standard podcast and voice-over sound. The music is looped or trimmed to the voice length, starts at the chosen bed level and fades out at the end; the voice is levelled first. Depth of ducking and music level are selectable, and the mix is brought to the target loudness, measured afterwards.

## Output

A single mixed audio file (MP3, WAV, FLAC, or Opus) in which the music track has been looped or trimmed to match the voice length, sidechain-ducked under speech, faded out at the end, and normalised to the specified LUFS target. The voice is levelled before mixing.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "music": {
   "type": "object",
   "properties": {
    "url": {
     "type": "string",
     "maxLength": 2048
    },
    "filename": {
     "type": "string",
     "maxLength": 260
    },
    "content_base64": {
     "type": "string",
     "maxLength": 5500000
    }
   },
   "additionalProperties": false
  },
  "voice": {
   "type": "object",
   "properties": {
    "url": {
     "type": "string",
     "maxLength": 2048
    },
    "filename": {
     "type": "string",
     "maxLength": 260
    },
    "content_base64": {
     "type": "string",
     "maxLength": 5500000
    }
   },
   "additionalProperties": false
  },
  "duck_ratio": {
   "type": "number",
   "default": 8,
   "maximum": 20,
   "minimum": 2,
   "description": "How strongly the music dips under speech."
  },
  "target_lufs": {
   "type": "number",
   "default": -16,
   "maximum": -12,
   "minimum": -24
  },
  "output_format": {
   "enum": [
    "opus",
    "mp3",
    "wav",
    "flac"
   ],
   "type": "string",
   "default": "mp3"
  },
  "music_level_db": {
   "type": "number",
   "default": -12,
   "maximum": 0,
   "minimum": -30,
   "description": "Music level when nobody speaks, relative to the voice."
  },
  "duration_minutes": {
   "type": "integer",
   "maximum": 30,
   "minimum": 1,
   "description": "Length of the voice track in started minutes."
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/halowerk-music-ducking-sidechain-compression-mix-c6b52202/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from medien.halowerk.com](https://www.zero.xyz/host/medien.halowerk.com/llms.txt)