docs: README with installation and usage instructions

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

README.md

@@ -0,0 +1,106 @@
+# ComfyUI-PrismAudio
+
+Custom nodes for [PrismAudio](https://github.com/FunAudioLLM/ThinkSound) (ICLR 2026) — video-to-audio and text-to-audio generation using decomposed Chain-of-Thought reasoning with a 518M parameter DiT diffusion model and Stable Audio 2.0 VAE.
+
+## Installation
+
+Clone into your ComfyUI custom nodes directory:
+
+```bash
+cd ComfyUI/custom_nodes
+git clone -b prismaudio https://github.com/FunAudioLLM/ThinkSound ComfyUI-PrismAudio
+pip install -r ComfyUI-PrismAudio/requirements.txt
+```
+
+**flash-attn** is optional. It is detected at runtime and falls back to PyTorch SDPA if unavailable.
+
+For the **Feature Extractor** node (video feature extraction), a separate conda environment is required — see [Feature Extraction Environment](#feature-extraction-environment) below.
+
+## Nodes
+
+| Node | Description |
+|------|-------------|
+| **PrismAudio Model Loader** | Loads the diffusion model and VAE. Auto-downloads weights from HuggingFace. Inputs: `precision` (auto/fp32/fp16/bf16), `offload_strategy` (auto/keep_in_vram/offload_to_cpu). |
+| **PrismAudio Feature Loader** | Loads pre-computed `.npz` feature files for use with the sampler. |
+| **PrismAudio Feature Extractor** | Subprocess bridge that extracts features from video. Requires a separate conda env with JAX/TF. |
+| **PrismAudio Sampler** | Main generation node. Takes model + features, produces AUDIO. Inputs: `duration`, `steps`, `cfg_scale`, `seed`. |
+| **PrismAudio Text Only** | Text-to-audio generation without video. Uses the T5-Gemma text encoder. Inputs: `text_prompt`, `duration`, `steps`, `cfg_scale`, `seed`. |
+
+## Workflows
+
+### Quality Path (Video-to-Audio)
+
+```
+Video → PrismAudio Feature Extractor → PrismAudio Sampler → Save Audio
+```
+
+### Pre-computed Path
+
+```
+PrismAudio Feature Loader (.npz) → PrismAudio Sampler → Save Audio
+```
+
+### Text-Only
+
+```
+PrismAudio Text Only → Save Audio
+```
+
+> **Note:** CoT text is a STRING input on the sampler. You can use any existing ComfyUI LLM nodes to generate it.
+
+## HuggingFace Authentication
+
+Required for gated models (T5-Gemma, and possibly Stable Audio VAE).
+
+1. Visit <https://huggingface.co/FunAudioLLM/PrismAudio> and accept the license.
+2. Authenticate via one of:
+   - **Environment variable:** `export HF_TOKEN=hf_...`
+   - **CLI login:** `huggingface-cli login`
+
+There is no `hf_token` widget on the nodes by design — ComfyUI saves all STRING values to workflow JSON, which would expose your token.
+
+## Model Files
+
+Weights are auto-downloaded to `ComfyUI/models/prismaudio/`:
+
+| File | Size | Description |
+|------|------|-------------|
+| `prismaudio.ckpt` | ~2.7 GB | Diffusion model |
+| `vae.ckpt` | ~2.5 GB | Stable Audio 2.0 VAE |
+| `synchformer_state_dict.pth` | ~950 MB | Synchformer |
+
+T5-Gemma is cached in the standard HuggingFace cache directory (`~/.cache/huggingface/`).
+
+## VRAM Requirements
+
+| VRAM | Strategy |
+|------|----------|
+| 24 GB+ | Keep all models in VRAM |
+| 12–24 GB | Sequential offload |
+| 8–12 GB | Aggressive offload + fp16 |
+| < 8 GB | May work with aggressive offload |
+
+## Feature Extraction Environment
+
+The **PrismAudio Feature Extractor** node runs extraction in a subprocess using a separate Python environment (JAX/TF dependencies).
+
+```bash
+conda env create -f scripts/environment.yml
+conda activate prismaudio-extract
+```
+
+Then set the `python_env` input on the Feature Extractor node to:
+
+```
+/path/to/conda/envs/prismaudio-extract/bin/python
+```
+
+## Troubleshooting
+
+- **Gated model errors** — Accept the license at <https://huggingface.co/FunAudioLLM/PrismAudio> and set `HF_TOKEN`.
+- **VRAM errors** — Switch `offload_strategy` to `offload_to_cpu`, or use `fp16` precision.
+- **flash-attn** — Purely optional. Auto-detected at runtime; falls back to PyTorch SDPA.
+
+## Credits
+
+PrismAudio by [FunAudioLLM](https://github.com/FunAudioLLM) (ICLR 2026). [Paper & code](https://github.com/FunAudioLLM/ThinkSound).