---
license: mit
pipeline_tag: text-to-speech
library_name: rlx
tags:
- tts
- melotts
- vits2
- rlx
- rlxp
---

# TinyTTS / MeloTTS RLX bundle

MeloTTS/VITS2 English nested `.rlxp` subgraphs + frontend for RLX TinyTTS and MeloTTS. CPU / Metal / MLX / CUDA / wgpu.

| Field | Value |
|---|---|
| **Hub id** | [`eugenehp/tiny-tts-rlx`](https://huggingface.co/eugenehp/tiny-tts-rlx) |
| **Kind** | RLX-native weight bundle (graphs + sidecars ready for `rlx-*` crates). |
| **RLX crate** | [`rlx-tiny-tts`](https://github.com/MIT-RLX/rlx-models/tree/main/crates/rlx-tiny-tts) |
| **Upstream** | https://github.com/tronghieuit/tiny-tts |

## Quick start

```bash
just fetch-tiny-tts   # or: hf download eugenehp/tiny-tts-rlx tiny-tts.rlxp --local-dir weights/tts/tiny-tts-rlx
just fetch-tiny-tts && cargo run -p rlx-tiny-tts --release --features apple-silicon -- --data weights/tts/tiny-tts-rlx --text "Hi." --device metal --out /tmp/tiny.wav
```

## Primary files (use these)

- `tiny-tts.rlxp` — 29.4 MiB

## Contents

Hub ships `tiny-tts.rlxp` only (nested graph packs + frontend). Also used by `rlx-melotts` / `just fetch-melotts`. Runtime does **not** load `.onnx` from Hub.

## Pack layout (`.rlxp`)

Outer RLXPFLAT bundle: nested native subgraph packs under `graphs/` (hot weight tensors + graph IR sidecars) plus English frontend assets. No `.onnx` on Hub. `rlx-tiny-tts` materializes the outer pack, then lowers each nested pack to HIR for the utterance length.

Official RLX package format (`RLXPFLAT`, container v2).

```text
[0..8)   magic          RLXPFLAT
[8..12)  version        u32 LE (= 2)
[12..16) flags          u32 LE (hybrid hot/warm/cold)
[16..24) toc_len        u64 LE
[24..)   TOC            JSON table of contents
         data region    64-byte aligned payloads
```

The TOC lists **tensors** (named weight blobs) and/or **sidecars** (files: ONNX,
tokenizers, manifests, …). Sidecars are usually **cold + zstd**; model weights in
tensor packs are **hot + uncompressed** for mmap. Runtime crates open the pack
directly (or materialize sidecars to a temp dir for asset-only packs).

### This pack

| Field | Value |
|---|---|
| **File** | `tiny-tts.rlxp` (29.4 MiB) |
| **Manifest name** | `tiny-tts` |
| **Producer** | `rlx-assets` |
| **Container** | RLXPFLAT v2, flags=0x1 |
| **Tensors** | 0 |
| **Sidecars** | 16 |

### Sidecars (file assets)

Outer TOC is file sidecars only. Neural weights live **inside** each `graphs/<name>.rlxp` as hot mmap tensors (not safetensors).

Paths below are logical ids inside the pack (`__flat__/sidecar/<id>`).
Cold sidecars are zstd-compressed; sizes show raw → stored.

| Sidecar | Raw | Stored | Role |
|---|---:|---:|---|
| `config.json` | 325 B | 220 B | Model / sample-rate config (44.1 kHz) |
| `frontend/bert/tokenizer.json` | 694.7 KiB | 214.5 KiB | BERT WordPiece tokenizer |
| `frontend/bert/tokenizer_config.json` | 351 B | 218 B | Tokenizer config |
| `frontend/cmudict_rep.txt` | 3.9 MiB | 1.0 MiB | CMUdict repair / variants |
| `frontend/g2p_checkpoint.safetensors` | 3.2 MiB | 3.0 MiB | G2P checkpoint |
| `frontend/g2p_cmudict.txt` | 3.3 MiB | 995.6 KiB | CMUdict for G2P |
| `frontend/homographs.en` | 18.3 KiB | 5.0 KiB | Homograph list |
| `frontend/perceptron_tagger.json` | 5.4 MiB | 1.5 MiB | POS tagger |
| `frontend/symbols.json` | 2.1 KiB | 726 B | Symbol table |
| `graphs/decoder.rlxp` | 13.7 MiB | 12.5 MiB | Nested pack: hot tensors + graph.json |
| `graphs/duration_predictor.rlxp` | 1.0 MiB | 598.8 KiB | Nested pack: hot tensors + graph.json |
| `graphs/flow.rlxp` | 13.7 MiB | 8.0 MiB | Nested pack: hot tensors + graph.json |
| `graphs/text_encoder.rlxp` | 2.9 MiB | 1.7 MiB | Nested pack: hot tensors + graph.json |

### Architecture

**Pipeline:** text → English frontend (G2P) → `text_encoder` → `duration_predictor` → monotonic alignment + latent sample (Rust) → `flow` → `decoder` → 44.1 kHz mono WAV.

| Module | Role | Typical dtype | Notes |
|---|---|---|---|
| `text_encoder` | phone/tone/lang → latent | f32 | length = phoneme count `T` |
| `duration_predictor` | per-phone duration | f32 | |
| `flow` | prior / flow | f32 | |
| `decoder` | HiFi-GAN-style vocoder | f32 | ConvTranspose upsample ×512 |
| frontend | G2P + BERT tokenizer + CMUdict | — | file sidecars |

### Logical tree

```text
tiny-tts.rlxp
├── graphs/
│   ├── text_encoder.rlxp      # hot f32/i64 + graph.json
│   ├── duration_predictor.rlxp
│   ├── flow.rlxp
│   └── decoder.rlxp
├── config.json
└── frontend/                 # G2P / tokenizer (not neural)
```

### How it is packed

`just export-tiny-tts-rlxp` / `pack_rlxp` example: ONNX pack-time source → nested `graphs/*.rlxp` via `rlx-assets` native-pack, then outer bundle. Hub artifact has zero `.onnx`.

## Note

MeloTTS (`rlx-melotts`) loads this same bundle — locally `weights/tts/melotts` is a symlink.

## Note

Hub ships **no ONNX**. Nested `graphs/*.rlxp` hold hot f32/i64 tensors + `graph.json`; the crate lowers to HIR per utterance length.

## Run with RLX

Clone [rlx-models](https://github.com/MIT-RLX/rlx-models), place this repo under `weights/tts/tiny-tts-rlx` (or pass the path explicitly), then:

```bash
just fetch-tiny-tts && cargo run -p rlx-tiny-tts --release --features apple-silicon -- --data weights/tts/tiny-tts-rlx --text "Hi." --device metal --out /tmp/tiny.wav
```

## License

MIT — see `LICENSE`. Inherit upstream terms when redistributing.

Original weights and authorship: https://github.com/tronghieuit/tiny-tts

## Maintenance

Cards and LFS attrs are regenerated from the local `weights/` tree in [rlx-models](https://github.com/MIT-RLX/rlx-models) via `python3 scripts/prepare_weights_hf.py`.