| --- |
| library_name: pytorch |
| license: other |
| license_name: blizzard-2013-non-commercial |
| license_link: LICENSE |
| --- |
| |
| # Piper VITS en_US Lessac Medium (Ambarella N1-655 CVflow v3 NVP) |
| |
| Piper VITS (`en_US-lessac-medium`) is a neural text-to-speech (TTS) model based on VITS (Variational Inference with adversarial learning for end-to-end Text-to-Speech), partitioned into a static-shape phoneme encoder (`vits_enc.bin`) and a 50-frame overlap-tiled waveform decoder (`vits_dec.bin`) for the Ambarella N1-655 CVflow v3 NVP. |
|
|
| > [!IMPORTANT] |
| > **Non-Commercial Dataset Notice (`blizzard-2013-non-commercial`)**: While the Piper VITS model architecture and code are licensed under the **MIT License**, the `en_US-lessac-medium` voice checkpoint was trained on the **Blizzard Challenge 2013 (Lessac Technologies, Inc.)** dataset. Under the Blizzard Challenge 2013 dataset license terms, these voice weights are restricted to **non-commercial research, educational, and demonstration use only** and may not be used for commercial purposes without separate authorization from Lessac Technologies, Inc. |
| |
| Original paper: [Conditional Variational Autoencoder with Adversarial Learning for End-to-End Text-to-Speech](https://arxiv.org/abs/2106.06103) |
| |
| Model Configuration: |
| - Reference implementation: [https://github.com/rhasspy/piper](https://github.com/rhasspy/piper) |
| - Original Weight: [https://huggingface.co/rhasspy/piper-voices/tree/main/en/en_US/lessac/medium](https://huggingface.co/rhasspy/piper-voices/tree/main/en/en_US/lessac/medium) |
| - Dataset: Blizzard Challenge 2013 — Lessac Technologies, Inc. (Non-Commercial Research License) |
| - License: other (`blizzard-2013-non-commercial`, see `LICENSE` — MIT code + Blizzard Challenge 2013 Non-Commercial Dataset) |
| - Support Cooper version: |
| - CNNGen: `[3.9.0 / n1-655x]` (`cavalry_gen 3.0.4`) |
|
|
| ## Upstream Attribution & Modification Notice |
| - **Upstream Code & Architecture Copyright**: Copyright (c) 2023 Michael Hansen (`rhasspy` / OHF-Voice `piper`), licensed under the MIT License. |
| - **Upstream Voice Dataset License (`blizzard-2013-non-commercial`)**: The `en_US-lessac-medium` voice weights are derived from the **Blizzard Challenge 2013** corpus provided by **Lessac Technologies, Inc.** and distributed for **non-commercial research, educational, and evaluation use only**. |
| - **Modification Notice**: Modified by Ambarella International LLC (2026). Partitioned at the stochastic duration predictor / length regulator into Stage 0 (`vits_enc.bin`) and Stage 1 50-frame overlap-tiled HiFi-GAN decoder (`vits_dec.bin`), and compiled via Ambarella Cooper SDK CNNGen 3.9.0 (`cavalry_gen 3.0.4`) for CVflow v3 N1-655 (`vdg_arch = 0xB`). |
|
|
| ## NVP Port & Runtime Specification |
| - **Target SoC**: Ambarella N1-655 (`vdg_arch = 0xB`, CVflow v3 `cavalry_gen` 3.0.4) |
| - **Archive members**: `vits_enc.bin`, `vits_dec.bin`, `phoneme_id_map.json` |
| - **Stage 0 (`vits_enc.bin`)**: `input` `[1, 128]` int16, `x_mask` `[1, 1, 128]` FP16 -> `m_p` `[1, 192, 128]`, `logs_p` `[1, 192, 128]`, `logw` `[1, 1, 128]` IEEE FP16 |
| - **CPU Bridge**: `d_i = ceil(exp(logw_i) * x_mask_i * length_scale)`, expand `m_p`/`logs_p` to `[1, 192, 500]` (`y_mask` `[1, 1, 500]`) |
| - **Stage 1 (`vits_dec.bin`)**: 50-frame overlap-tiled (`core=20, ctx=15`) `z_p` `[1, 192, 50]`, `y_mask` `[1, 1, 50]` FP16 -> `audio` `[1, 1, 1, 12800]` IEEE FP16 @ 22.05 kHz (hop=256) |
| |
| | Model | Device | Compression | Model Link | |
| | :---: | :---: | :---: | :--- | |
| | Piper | N1-655 | Amba_optimized | [Model_Link](https://huggingface.co/cchiou-amba/Piper/blob/main/n1-655_piper_vits_lessac_amba_optimized.tar.gz) | |
| |
