rhymeswithlion/magenta-realtime-mlx-cpp

Magenta RealTime — C++ MLX runtime bundle

This dataset is a re-packaging of Google's Magenta RealTime weights for the C++ MLX runtime in rhymeswithlion/magenta-realtime-mlx-cpp.

It contains exactly what mlx-stream needs at startup; nothing more, nothing less. The upstream .pt / .npy checkpoints are intentionally not mirrored here — they're only useful for the (Python) re-export tooling on the project's main distribution.

Contents

.
├── spectrostream_encoder.safetensors      (35 MB)
├── spectrostream_decoder.safetensors     (136 MB)
├── spectrostream_codebooks.safetensors    (64 MB)
├── musiccoca_encoder.safetensors         (911 MB)
├── musiccoca_codebooks.safetensors        (36 MB)
├── musiccoca_vocab.model                 (1.5 MB)
├── depthformer/
│   └── depthformer_base.safetensors     (1.33 GB)
└── mlxfn/
    ├── encode_base_bf16.mlxfn               (~5 MB)
    ├── depth_step_base_bf16_cl01.mlxfn        ...
    │   ...
    ├── depth_step_base_bf16_cl15.mlxfn      (15 files, ~4 KB each)
    ├── temporal_step_base_bf16_cl01.mlxfn     ...
    │   ...
    ├── temporal_step_base_bf16_cl49.mlxfn   (49 files, ~200 KB each)
    └── manifest.json

Total: 73 files, ~2.7 GB.

Most .safetensors are direct conversions of the upstream .pt / .npy artefacts (tensor keys, dtypes, and storage layout preserved verbatim). The exception is musiccoca_encoder.safetensors, which has been lightly fine-tuned to better match the original (pre-conversion) MusicCoCa XLA SavedModel's outputs — see the provenance table at the bottom.

The mlxfn/*.mlxfn files are mx::export_function serialisations of the Depthformer encode + per-cache-length decode steps. They're an optional accelerator: the C++ binary still works without them, but falls back to a ~50 % slower capturing-lambda compile path. Weights are passed in as flowing function arguments, so each .mlxfn file is small (KB-scale, not GB).

How to use

The runtime expects this exact layout under .weights-cache/. The repo's Makefile does the right thing:

git clone https://github.com/rhymeswithlion/magenta-realtime-mlx-cpp
cd magenta-realtime-mlx-cpp
make mlx-stream

This invokes scripts/download_weights_from_hf.py (which snapshots this dataset into .weights-cache/), builds the C++ binary, and starts streaming audio.

To download the bundle by itself:

huggingface-cli download \
  --repo-type dataset \
  rhymeswithlion/magenta-realtime-mlx-cpp \
  --local-dir ./weights-cache

License

This bundle is licensed under Creative Commons Attribution 4.0 International (CC-BY-4.0), matching the upstream google/magenta-realtime weights.

Copyright 2025 Google LLC.

musiccoca_encoder.safetensors has been lightly fine-tuned to better match the outputs of the original (pre-conversion) MusicCoCa XLA SavedModel, and the resulting fine-tune deltas are licensed under Apache License 2.0, Copyright 2026 Brian Cruz. It is shape-compatible with the upstream encoder and is loaded by the runtime without code changes.

The C++ MLX runtime that consumes these weights (rhymeswithlion/magenta-realtime-mlx-cpp) is also licensed under Apache License 2.0, Copyright 2026 Brian Cruz.

Magenta RealTime Terms of Use

Reproduced from the upstream model card:

Magenta RealTime is offered under a combination of licenses: the codebase is licensed under Apache 2.0, and the model weights under Creative Commons Attribution 4.0 International. In addition, we specify the following usage terms:

Copyright 2025 Google LLC

Use these materials responsibly and do not generate content, including outputs, that infringe or violate the rights of others, including rights in copyrighted content.

Google claims no rights in outputs you generate using Magenta RealTime. You and your users are solely responsible for outputs and their subsequent uses.

Unless required by applicable law or agreed to in writing, all software and materials distributed here under the Apache 2.0 or CC-BY licenses are distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the licenses for the specific language governing permissions and limitations under those licenses. You are solely responsible for determining the appropriateness of using, reproducing, modifying, performing, displaying or distributing the software and materials, and any outputs, and assume any and all risks associated with your use or distribution of any of the software and materials, and any outputs, and your exercise of rights and permissions under the licenses.

Attribution

Please attribute Google's Magenta RealTime when using this bundle:

@article{gdmlyria2025live,
    title={Live Music Models},
    author={Caillon, Antoine and McWilliams, Brian and Tarakajian, Cassie
            and Simon, Ian and Manco, Ilaria and Engel, Jesse and Constant,
            Noah and Li, Pen and Denk, Timo I. and Lalama, Alberto and
            Agostinelli, Andrea and Huang, Anna and Manilow, Ethan and
            Brower, George and Erdogan, Hakan and Lei, Heidi and Rolnick,
            Itai and Grishchenko, Ivan and Orsini, Manu and Kastelic, Matej
            and Zuluaga, Mauricio and Verzetti, Mauro and Dooley, Michael
            and Skopek, Ondrej and Ferrer, Rafael and Borsos, Zal{\'a}n and
            van den Oord, {\"A}aron and Eck, Douglas and Collins, Eli and
            Baldridge, Jason and Hume, Tom and Donahue, Chris and Han,
            Kehang and Roberts, Adam},
    journal={arXiv:2508.04651},
    year={2025}
}

Source bundle provenance

Artefact	Source
spectrostream_*.safetensors	Converted from upstream spectrostream_*.pt / .npy
musiccoca_encoder.safetensors	Converted from upstream musiccoca_encoder.pt, then lightly fine-tuned by Brian Cruz to better match the original (pre-conversion) MusicCoCa XLA SavedModel; fine-tune deltas Apache-2.0
musiccoca_codebooks.safetensors	Converted from upstream musiccoca_codebooks.npy
musiccoca_vocab.model	Verbatim copy of upstream SentencePiece vocab
depthformer/depthformer_base.safetensors	Converted from upstream depthformer_base.pt
mlxfn/*.mlxfn	Traced via mx.export_function from the converted weights

Conversion + export tooling is published separately and is not part of this runtime bundle.