Supertonic 2

Supertone's Supertonic 2 on-device TTS model, exported for loom.cpp. Encodes text itself -- no external phonemiser needed.

This is a loom.cpp export: a single self-describing GGUF that carries its own graph topologies, tokenizer (if any) and driver script, produced by loom-exporter.

Original model

Exported from Supertone/supertonic-2. Weights are unmodified; this repo packages the same parameters into loom.cpp's GGUF format.

License

OpenRAIL-M -- inherited from the base model above.

Language(s)

en, ko, es, pt, fr

Usage

Run it with loom-py -- loom-py-rt on PyPI:

pip install -U "loom-py-rt[hub]"

import loom

model = loom.Model.from_pretrained("loom-ai-org/supertonic-2-loom")

# This model encodes text itself -- no phonemiser needed at all.
print(model.tokenizer)                       # kind, vocabulary size, default language

# sample_rate=44100: a rate is not something a checkpoint necessarily carries, so it is a value
# you have to know from the model's documentation and pass. It is used only if the GGUF declares none;
# a wrong rate does not fail, it plays the voice at the wrong speed.
audio = model.text2speech.infer("hello world", sample_rate=44100)
audio.save("out.wav")

# That uses the voice the file itself defaults to. Whether it carries others is under "Known
# limitations" (and, where it does, a section below says how to pick one).

Choosing a voice

This file embeds one voice (F1) and uses it whenever no style is passed. Nine more ship in this repo under voice_styles/:

import json
from huggingface_hub import hf_hub_download

path = hf_hub_download("loom-ai-org/supertonic-2-loom", filename="voice_styles/M1.json")
style = json.load(open(path))

# Each file holds two embeddings, stored with a leading batch axis: style_ttl is (1, 50, 256) and
# style_dp is (1, 8, 16). `infer` takes them flat, so drop the batch axis and concatenate the rows.
flatten = lambda entry: [v for row in entry["data"][0] for v in row]
style_ttl = flatten(style["style_ttl"])   # 50 * 256 = 12800 floats
style_dp = flatten(style["style_dp"])     #  8 *  16 =   128 floats

# The door passes any input it does not name straight to the model, so a style rides along with the
# text -- and what comes back is still `loom.Audio`, at the file's own rate.
audio = model.text2speech.infer("hello world", style_ttl=style_ttl, style_dp=style_dp, seed=1234)
audio.save("m1.wav")

The two arguments travel together: pass neither for the built-in voice, or both to select another. A different voice predicts a different duration, so the waveform generally changes length as well as timbre.

Plain lists are fine -- this package has no runtime dependencies and accepts any sequence of floats, so numpy.asarray(...).ravel() works equally well if numpy is already around.

The layer underneath

The call above is the high-level door: one per task, named for the modality pair it maps between, with the windowing, sampling and assembly this model needs already applied. Under it, model.infer(...) passes your arguments straight to the driver this GGUF embeds -- which is where you go for a knob the door does not name.

model.driver_source prints that driver, including a header comment documenting every argument it accepts for this model, and is the authority on it. See loom-py for the API and loom.cpp for what the engine does between the two.

Known limitations

One synthesis call carries at most model.hparam("txt_len") ids -- 512 in this export, roughly 490 characters once the <lang>...</lang> wrap and the inserted final period are counted, so a short paragraph. Anything shorter is padded and masked by the driver, so any count up to the ceiling synthesizes correctly; anything longer has to be split by the caller, and this export deliberately does not do that for you (where a sentence may be broken is a text-domain decision, not a model contract). The text length is fixed rather than dynamic for two independent reasons -- a single dynamic-length symbol per graph, and a relative-position windowing step that cannot be traced dynamically -- so the graphs are traced at several widths and the driver runs the smallest that fits your text. Short text therefore does not pay for the ceiling.

One voice is built in. infer uses it when you pass no style, and takes any other voice as a style_ttl/style_dp pair. What this export does not carry is the two style encoders, so it cannot derive a style from your own audio -- cloning a new voice needs the upstream checkpoint. Selecting among existing voices does not.

Files

• supertonic-2.gguf -- the model, exported with loom-exporter.
• voice_styles/*.json -- ten precomputed voices (F1-F5, M1-M5), copied unmodified from the upstream checkpoint. F1 is also embedded in the GGUF as the default, so these are only needed to select a different voice. See the usage example above.