📢 Request: English-only Kokoro v1.0 + Opset 4 Compatible Quantized Model for iOS

[abdussamad0]

Hi Sherpa-ONNX team 👋,

Thank you for all the incredible work on Sherpa-ONNX — especially the TTS capabilities. I’m currently integrating your models into a Flutter-based iOS app, and I’d like to request support for a mobile-compatible version of Kokoro.

⸻

✅ Request #1: English-only version of Kokoro v1.0

There is a need for a version of Kokoro v1.0 that contains only the English speakers to reduce model size and simplify integration in mobile apps (especially where multilingual support isn’t required).

We found relevant models hosted here:
• 🔗 https://github.com/thewh1teagle/kokoro-onnx/releases/tag/model-files
• 🔗 https://huggingface.co/NeuML/kokoro-int8-onnx/tree/main

However, all of these models crash on iOS due to the issue described below.

⸻

❗ Problem: Opset 5 / ai.onnx.ml Compatibility on iOS

When trying to run the model in our Flutter app on iPhone (using ONNX Runtime for iOS), the app crashes with the following exception:

Ort::Exception: Failed to load model...
ONNX Runtime only guarantees support for opsets officially released.
Opset 5 for domain ai.onnx.ml is under development...
Current official support is up to opset 4.

So while kokoro-v1_0-en-int8.onnx does work perfectly on macOS (M4 Mac Mini), it fails to load in iOS due to ONNX Runtime’s limited opset support for ai.onnx.ml.

⸻

✅ Request #2: Quantized version of Kokoro v1.0 (English-only) using Opset 4

If there’s a delay in officially releasing these versions, could you please:
• Provide an Opset 4-compatible quantized ONNX version of Kokoro (English-only)?
• Or share guidance on how we could re-export the model to use opset 4 for ai.onnx.ml?

Even basic model conversion tips or a script suggestion would help — the goal is to get Kokoro running on iOS without crashing due to opset errors.

⸻

🔧 Ideal Files to Include

If possible, please consider providing:
• kokoro-v1_0-en-int8-opset4.onnx
• tokens.txt
• voices.bin (with only English speakers)
• espeak-ng-data (trimmed for English phonemes only)

⸻

Thank you again for all the amazing work!
Happy to help test, validate, or debug on Flutter/iOS if needed. 🙏

[csukuangfj]

closed by #2137

[abdussamad0]

If possible, could you kindly share any guidance on how I might re-export the Kokoro quantized model using opset 4 for the ai.onnx.ml domain, so it can run successfully with ONNX Runtime on iOS?

[csukuangfj]

You can find export_onnx.py in https://github.com/k2-fsa/sherpa-onnx/pull/2137/files

You need to figure it out by yourself.