---
license: apache-2.0
tags:
  - qhexrt
  - melotts
  - tts
  - hexagon
  - npu
  - qnn
language:
  - en
pipeline_tag: text-to-speech
---

# MeloTTS-EN — QHexRT NPU bundle (Hexagon v79)

Precompiled **MeloTTS English** text-to-speech for the **QHexRT** runtime on Qualcomm Hexagon **v79**
(Snapdragon 8 Elite / SM8750, e.g. Galaxy S25). The 3 acoustic graphs (encoder → flow → decoder) are
Qualcomm AI Hub `qnn_context_binary` graphs; the g2p frontend + duration alignment + vocoder windowing
are QHexRT's own host pipeline. Device-validated: text → 44.1 kHz mono audio.

Measured on S25/v79: ~1.0 s to synthesize 4.56 s of speech (≈4.5× real-time).

## Contents (`v79/`)
| file | what |
|------|------|
| `melotts-en.json` | QHexRT manifest (TTS family, `tts_synthesize` plan) |
| `melo_encoder.bin` | text/phoneme encoder (→ durations + priors) |
| `melo_flow.bin` | flow (normalizing-flow latent) |
| `melo_decoder.bin` | vocoder/decoder (→ waveform) |
| `melo_tokens.txt` | phoneme token table (g2p) |
| `melo_lexicon.txt` | open pronunciation lexicon (g2p) |

## Run (QHexRT CLI)
```bash
huggingface-cli download runanywhere/melotts_en_HNPU --local-dir melotts_en_HNPU
# QNN libs come from the QAIRT SDK (lib/aarch64-android) + the v79 HTP skel; push them next to qhx_say.
adb push melotts_en_HNPU/v79 /data/local/tmp/wq/melotts
adb shell "cd /data/local/tmp/wq && LD_LIBRARY_PATH=. ADSP_LIBRARY_PATH=. \
  ./qhx_say melotts/melotts-en.json libQnnHtp.so libQnnSystem.so melotts 'Hello from Hexagon.' melotts/out.wav"
# -> melotts/out.wav (44.1 kHz mono)
```

## Notes
- Arch: **v79** only (context binaries are dsp-arch-pinned).
- No custom op-package needed — pure-native AI Hub graphs.
- v1: no BERT prosody (ja_bert=0). English only.
- Source: MeloTTS-EN, compiled via Qualcomm AI Hub for `qualcomm-snapdragon-8-elite-for-galaxy`.