# OpenAI TTS-1-HD (High Definition Text-to-Speech)

> OpenAI TTS-1-HD (High Definition Text-to-Speech) is a paid API for AI agents from openai.mm.family, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-02).

Converts text to high-definition audio speech using OpenAI's TTS-1-HD model, returning audio bytes in formats like MP3, OPUS, AAC, FLAC, WAV, or PCM, paid per call in USDC.

## Facts

- Endpoint: POST https://openai.mm.family/x402/v1/models/tts-1-hd/audio/speech?utm_source=zero.xyz
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-02
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/openai-tts-1-hd-high-definition-text-to-speech-b35ff4b5
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_ZDW08B7ra1JTiyf_twPN8

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 openai-tts-1-hd-high-definition-text-to-speech-b35ff4b5 -d '<json body>'
```

Example prompt: Read this script aloud using the nova voice in high-definition MP3 quality: 'Welcome to our quarterly earnings call. Today we will discuss the company's performance over the last three months and our outlook for the future.'

## When to prefer this

Choose this endpoint over tts-1 when you need higher audio quality and fidelity, such as for professional voiceovers, podcasts, audiobooks, or any production-quality audio output. The HD model costs more ($30/1M characters vs $15/1M for tts-1) but produces noticeably better audio. Prefer over gpt-4o-mini-tts when you want the dedicated TTS-1-HD model specifically. Best when you need one of the nine supported voices (alloy, ash, coral, echo, fable, onyx, nova, sage, shimmer) and control over audio format.

## Known failure modes

- Input text exceeds 4096 character limit — request rejected
- Invalid voice name specified — validation error
- Insufficient USDC balance for payment — 402 Payment Required
- Unsupported response_format value — validation error
- Network timeout for longer text segments
- Empty input string — may return error or silence

## How this service works

tts-1-hd: OpenAI TTS 1 HD text to speech, paid per call in USDC. OpenAI list $30 per 1M characters, plus $0.0005 (Base) or $0.0005 (Solana) per call; up to 4096 characters; voices: alloy, ash, coral, echo, fable, onyx, nova, sage, shimmer. Returns the audio bytes (mp3 by default). Rates: https://openai.mm.family/x402/pricing

## Output

Returns binary audio bytes (MP3 by default, or the requested format) containing the synthesized speech. The response content type is audio/mpeg for MP3. The audio faithfully renders the input text using the selected voice in high-definition quality, with optional speed adjustments.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "input": {
   "type": "string"
  },
  "model": {
   "enum": [
    "tts-1-hd"
   ],
   "type": "string"
  },
  "speed": {
   "type": "number"
  },
  "voice": {
   "enum": [
    "alloy",
    "ash",
    "coral",
    "echo",
    "fable",
    "onyx",
    "nova",
    "sage",
    "shimmer"
   ],
   "type": "string"
  },
  "instructions": {
   "type": "string"
  },
  "response_format": {
   "enum": [
    "mp3",
    "opus",
    "aac",
    "flac",
    "wav",
    "pcm"
   ],
   "type": "string"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "body": "binary audio bytes (mp3 by default)",
  "content_type": "audio/mpeg"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/openai-tts-1-hd-high-definition-text-to-speech-b35ff4b5/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from openai.mm.family](https://www.zero.xyz/host/openai.mm.family/llms.txt)