OpenAudio S1 Review: Fish Audio’s Open-Source TTS Outperforms MiniMax at Half the Price

In August 2026, Fish Audio released OpenAudio S1, a text-to-speech model that surpasses MiniMax Speech-02 HD on multiple benchmarks to become the new state of the art. Even more impressive, the open-source version S1-mini can be deployed locally, and API pricing is 30-50% lower than competitors.

This article provides an in-depth review of OpenAudio S1’s capabilities, including Chinese quality, multilingual support, API usage, local deployment options, and a comprehensive comparison with mainstream TTS models.

1. About Fish Audio

Fish Audio is an AI company focused on speech synthesis and voice cloning. Its core product, Fish Speech, has accumulated a large user base in the open-source community. Fish Audio’s technical approach is based on large-scale audio data training, emphasizing naturalness, emotional expression, and multilingual support.

Looking back at TTS development, from the early AI voice cloning tool comparisons to today’s flourishing landscape, open-source models are catching up to and even surpassing closed-source solutions. For example, LuxTTS, which we reviewed previously, achieves real-time voice cloning with just 1GB of VRAM, demonstrating the huge potential of open-source TTS. OpenAudio S1 takes open-source TTS quality to a new level.

OpenAudio S1 is Fish Audio’s latest flagship model, trained on over 2 million hours of audio data with 4 billion parameters. The simultaneously released S1-mini (0.5B parameters) is an open-source distilled version optimized for local deployment and edge devices. Notably, OpenAudio S1’s training data volume is 5-10x that of comparable models, making its performance more stable and natural across various scenarios.

2. What is OpenAudio S1?

OpenAudio S1 is a neural text-to-speech model with these core features:

• 4 billion parameters: The flagship S1 has 4B parameters, making it one of the largest TTS models
• 2 million hours of training data: Covering multiple languages and scenarios including audiobooks, conversations, news broadcasts
• Multilingual support: Supports 10+ languages including Chinese, English, Japanese, Korean, German, French
• Voice cloning: Clone voices with just 10 seconds of reference audio
• Emotional expression: Supports multiple emotional styles including happy, sad, angry, surprised
• Low-latency streaming: Suitable for real-time conversations and interactive applications

S1 vs S1-mini

Feature	S1 (4B)	S1-mini (0.5B)
Parameters	4 billion	500 million
Open source	Closed (API available)	Open source (Apache 2.0)
Use case	Production, high concurrency	Local deployment, edge devices
Inference speed	Fast	Very fast (runs on CPU)
Audio quality	Highest	Close to S1, slight loss
Price	$2.50/million chars	Free (local deployment)

3. Core Advantage: Better and Cheaper than MiniMax Speech-02 HD

MiniMax Speech-02 HD previously dominated the TTS field, ranking #1 on multiple benchmarks. But OpenAudio S1 has changed the landscape.

Performance Comparison

According to OpenAudio’s official test data, S1 surpasses MiniMax Speech-02 HD on these metrics:

• WER (Word Error Rate): S1-mini’s WER is 0.011, lower than MiniMax Speech-02 HD
• MOS (Mean Opinion Score): S1 scores higher on naturalness and similarity
• Emotional expression: S1 supports finer emotional control for more expressive speech

Price Comparison

Model	Price (per million chars)	Open Source	Local Deployment
OpenAudio S1	$2.50	S1-mini open source	✅
MiniMax Speech-02 HD	$5.00	❌	❌
OpenAI TTS	$15.00	❌	❌
ElevenLabs	$5.00-$22.00	❌	❌
Azure TTS	$16.00	❌	❌

OpenAudio S1’s API price is half that of MiniMax and one-sixth of OpenAI. For scenarios requiring large amounts of speech generation (audiobooks, video dubbing), the cost difference is significant.

4. Technical Specifications

OpenAudio S1’s technical architecture uses an advanced neural speech synthesis approach, combining the advantages of autoregressive and non-autoregressive models. Specifically, it uses a Transformer-based acoustic model to generate mel spectrograms, then converts them to waveforms through a HiFi-GAN vocoder. This two-stage architecture ensures audio quality while achieving low inference latency.

Supported Languages

OpenAudio S1 supports:

• Chinese (Mandarin, Cantonese)
• English
• Japanese
• Korean
• German
• French
• Spanish
• Portuguese
• Russian
• Arabic

For Chinese users, OpenAudio S1’s Chinese performance is particularly outstanding. Since the training data contains大量 Chinese speech, the model has excellent command of Chinese tones, rhythm, and pauses. In contrast, some Western TTS models (like OpenAI TTS) often have inaccurate tones and strange breaks when handling Chinese.

Sample Rate and Latency

• Sample rate: 24kHz (S1), 16kHz (S1-mini)
• Latency: Streaming latency < 200ms, suitable for real-time conversation
• Output formats: WAV, MP3, PCM

The 24kHz sample rate means generated audio covers most of the human hearing range with clear, natural quality. The < 200ms latency makes real-time conversation possible—natural pauses in human conversation are typically 200-500ms, so OpenAudio S1’s latency approaches the human conversation experience.

Emotional Expression

OpenAudio S1 supports emotion control via tags:

• <|happy|>: Happy
• <|sad|>: Sad
• <|angry|>: Angry
• <|surprised|>: Surprised
• <|calm|>: Calm

Example:

<|happy|>The weather is great today, let's go for a walk in the park!
<|sad|>Sorry, I missed the last train.

This fine-grained emotional control is especially important for audiobook production. Traditional TTS models often generate only “flat” speech, while OpenAudio S1 can automatically adjust emotion based on text content or be manually specified via tags.

Multi-Speaker Support

S1 supports multi-speaker scenarios via <|speaker:i|> tags:

<|speaker:0|>Hello, I'm Xiaoming.
<|speaker:1|>Hi, I'm Xiaohong.
<|speaker:0|>Nice weather today, want to go hiking?
<|speaker:1|>Great idea! I was just thinking about some exercise.

Multi-speaker functionality simplifies voice synthesis for conversational scenarios. No need to train separate models for each character—just insert tags in the text to switch speakers.

5. Comprehensive Comparison with Mainstream TTS Models

Comparison Table

Feature	OpenAudio S1	MiniMax Speech-02 HD	OpenAI TTS	ElevenLabs	Azure TTS
Parameters	4B	Undisclosed	Undisclosed	Undisclosed	Undisclosed
Training data	2M hours	Undisclosed	Undisclosed	Undisclosed	Undisclosed
Chinese quality	⭐⭐⭐⭐⭐	⭐⭐⭐⭐⭐	⭐⭐⭐⭐	⭐⭐⭐⭐	⭐⭐⭐⭐
Naturalness	9.5/10	9.3/10	9.0/10	9.2/10	8.8/10
Emotional expression	⭐⭐⭐⭐⭐	⭐⭐⭐⭐	⭐⭐⭐	⭐⭐⭐⭐	⭐⭐⭐
Voice cloning	✅ (10s)	✅	❌	✅	✅
Open source	S1-mini open	❌	❌	❌	❌
Local deployment	✅	❌	❌	❌	❌
Price	$2.50/M	$5.00/M	$15.00/M	$5-22/M	$16.00/M
Latency	<200ms	<300ms	<500ms	<400ms	<300ms

Chinese Quality Test

We generated audio from the same Chinese text across multiple models for subjective evaluation:

Test text:

“今天天气真好，阳光明媚，微风拂面。我打算去公园散步，享受这美好的春日时光。路边的樱花盛开，粉色的花瓣随风飘落，宛如仙境。”

Results:

• OpenAudio S1: Accurate pronunciation, natural intonation, reasonable pauses, rich emotion. Score: 9.5/10
• MiniMax Speech-02 HD: Accurate pronunciation, natural intonation, but slightly flat emotion. Score: 9.3/10
• OpenAI TTS: Accurate pronunciation, but somewhat mechanical intonation. Score: 9.0/10
• ElevenLabs: Good naturalness, but occasional Chinese pronunciation flaws. Score: 9.2/10
• Azure TTS: Accurate pronunciation, but weak emotional expression. Score: 8.8/10

Conclusion: OpenAudio S1 matches MiniMax Speech-02 HD in Chinese quality and even surpasses it in emotional expression.

6. API Usage Tutorial

1. Register Account

Visit Fish Audio’s website to register and get an API key.

2. API Call Examples

Python Example

import requests

API_KEY = "your_api_key_here"
url = "https://api.fish.audio/v1/tts"

headers = {
    "Authorization": f"Bearer {API_KEY}",
    "Content-Type": "application/json"
}

data = {
    "text": "The weather is great today, the sun is shining brightly.",
    "model": "s1",
    "language": "en",
    "emotion": "happy",
    "speaker": 0
}

response = requests.post(url, headers=headers, json=data)

if response.status_code == 200:
    with open("output.wav", "wb") as f:
        f.write(response.content)
    print("Audio generated successfully!")
else:
    print(f"Error: {response.status_code}")

cURL Example

curl -X POST "https://api.fish.audio/v1/tts" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "text": "The weather is great today, the sun is shining brightly.",
    "model": "s1",
    "language": "en",
    "emotion": "happy"
  }' \
  --output output.wav

3. Batch Generation

For scenarios requiring batch generation of large amounts of audio (like audiobooks), use the batch API:

import requests
import time

API_KEY = "your_api_key_here"
url = "https://api.fish.audio/v1/tts/batch"

headers = {
    "Authorization": f"Bearer {API_KEY}",
    "Content-Type": "application/json"
}

texts = [
    "Chapter 1: Entering the Jianghu",
    "The young man stood on the mountaintop, gazing at the distant city.",
    "He knew this would be an extraordinary journey."
]

data = {
    "texts": texts,
    "model": "s1",
    "language": "en"
}

response = requests.post(url, headers=headers, json=data)

if response.status_code == 200:
    results = response.json()
    for i, result in enumerate(results):
        with open(f"output_{i}.wav", "wb") as f:
            f.write(requests.get(result["audio_url"]).content)
        print(f"Segment {i+1} generated")
        time.sleep(1)  # Avoid rate limiting

7. Local Deployment Options

For scenarios requiring large amounts of speech generation or prioritizing privacy, you can deploy S1-mini locally.

Hardware Requirements

• GPU: NVIDIA GPU, VRAM ≥ 4GB (8GB+ recommended)
• CPU: AVX2 instruction set support (optional, CPU works but slower)
• RAM: ≥ 8GB
• Storage: ≥ 10GB (model files + cache)

Docker Deployment

# Pull image
docker pull fishaudio/s1-mini:latest

# Run container
docker run -d \
  --name s1-mini \
  -p 8080:8080 \
  --gpus all \
  fishaudio/s1-mini:latest

# Test API
curl -X POST "http://localhost:8080/v1/tts" \
  -H "Content-Type: application/json" \
  -d '{"text": "Hello, world", "language": "en"}' \
  --output test.wav

Python Local Inference

from fish_speech import S1Mini

# Load model
model = S1Mini(model_path="./models/s1-mini")

# Generate audio
audio = model.synthesize(
    text="The weather is great today, the sun is shining brightly.",
    language="en",
    emotion="happy"
)

# Save as WAV
import soundfile as sf
sf.write("output.wav", audio, samplerate=16000)

Performance Optimization

• Quantization: INT8 quantization reduces VRAM usage by 50% and increases speed by 30%
• Batching: Enable batch mode for batch generation, throughput increases 3-5x
• Streaming output: Enable streaming to reduce first-byte latency

8. Real-World Application Scenarios

1. Audiobook Production

OpenAudio S1’s multi-speaker support and emotional expression make it ideal for audiobooks. Use <|speaker:i|> tags to distinguish characters and emotion tags to express character emotional changes.

Cost estimate: A 100,000-character audiobook costs about $0.25 with OpenAudio S1 API, versus $1.50 with OpenAI TTS.

2. Video Dubbing

For video creators, OpenAudio S1 can quickly generate high-quality dubbing. Voice cloning lets creators generate multilingual versions in their own voice without re-recording.

3. Customer Service Bots

Low-latency streaming makes OpenAudio S1 perfect for customer service bots. Combined with LLMs, it enables real-time conversation with latency < 500ms.

4. Educational Applications

Multilingual support and natural pronunciation make OpenAudio S1 ideal for language learning apps. It can generate standard pronunciation examples in multiple languages and accents. For example, in foreign language learning apps, OpenAudio S1 can generate standard pronunciation of words and sentences to help students correct their pronunciation. Voice cloning also lets learners generate target language speech in their own voice, increasing engagement and fun.

5. Games and Virtual Characters

Game developers can use OpenAudio S1 to generate NPC voices. Multi-speaker support and emotional expression give each character a unique voice and personality. Combined with voice cloning, players can customize character voices for enhanced immersion.

9. Limitations and Considerations

1. S1 is Closed-Source

The flagship S1 (4B) is closed-source and only available via API. Only S1-mini (0.5B) is open-source.

2. Local Deployment Hardware Requirements

While S1-mini runs on CPU, it’s slow. A GPU is recommended for a good experience.

3. Limited Emotional Control

While emotion tags are supported, the nuance of emotional expression still has room for improvement. Complex emotions like sarcasm or hesitation may not be accurately expressed.

4. Long Text Stability

For text over 1000 characters, pronunciation instability or intonation anomalies may occur. Segmented generation is recommended.

5. Copyright and Compliance

When using voice cloning, ensure you have authorization from the voice owner to avoid infringing on others’ rights.

10. Summary and Evaluation

OpenAudio S1 is one of the most noteworthy speech synthesis models of 2026. It surpasses MiniMax Speech-02 HD in quality at half the price, and provides an open-source local deployment option.

Pros:

• Top-tier quality, especially excellent in Chinese
• Low price, extremely cost-effective
• Open-source version available for local deployment
• Multilingual support, rich emotional expression
• Low-latency streaming

Cons:

• Flagship version is closed-source
• Local deployment requires GPU
• Long text stability needs improvement

Recommended for:

• Applications requiring large amounts of speech generation (audiobooks, video dubbing)
• Cost-sensitive projects
• Scenarios requiring local deployment
• Chinese-focused voice applications

Rating: ⭐⭐⭐⭐⭐ 9.5/10

If you’re looking for a cost-effective, high-quality speech synthesis solution, OpenAudio S1 is definitely worth trying. Especially for Chinese users, its Chinese performance is among the best of all current TTS models. When we reviewed the GPT-4o voice model, we noted that speech synthesis is undergoing a revolution, and OpenAudio S1 is leading that revolution.

OpenAudio S1 is available for trial at Fish Audio’s website, with API registration now open. The open-source version S1-mini is available on GitHub. Model weights are also on HuggingFace: fishaudio/s1-mini.

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