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Davids048andClaude Fable 5.1 a5aa64ab6b [refactor]: decide every config value before the config freezes, and drop the from_pretrained keywords
VideoGenerator.from_pretrained(model_path, config) takes the same nested
settings as from_config; the 24 flat keywords, from_pretrained_kwargs_to_config,
FROM_PRETRAINED_KWARGS, and every flat_field in the schema are deleted.
nvfp4_fa4 is the typed field engine.attention.nvfp4_fa4, applied by a
resolution step. 65 call sites and the docs use the nested form; the three
kwargs golden cases are config cases with byte-identical results.

Every value is decided during resolution; no runtime code calls
with_override. The device offload policy (unified memory, MPS, layerwise
conflicts, lazy module load) runs as resolution steps in the main process
(fastvideo/api/device_policy.py), and the worker runs on the config it
receives. The LTX-2 refine defaults from model_index.json and the MiniMax-H3
schedule from fastvideo_inference.json are resolution steps
(fastvideo/api/checkpoint_defaults.py) that read local checkpoints or download
only those files; the H3 pipeline validates the schedule against the loaded
schedulers but no longer writes it. The preprocessing entry point passes the
downloaded local path as run state instead of a config override. Teacher and
critic models load with override_transformer_cls_name as a load argument.
The test isolation turns the device policy off, as it blocks downloads, so
that the goldens do not depend on the machine.

Against the 3f6893a0 goldens, every field still matches except boundary_ratio
and ltx2_vae_tiling (DESIGN section 9) and the fields that no longer exist.
The launcher and trainer YAML verifications report 0 unexplained differences.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
2026-10-04 07:14:31 +00:00

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# SPDX-License-Identifier: Apache-2.0
"""Stable Audio Open 1.0 — text-to-audio (baseline) example.
User story (game-audio designer, prototyping):
"I'm prototyping a level and I need 6 seconds of background
ambience — gentle wind, distant thunder, a hint of birdsong. I
don't want to dig through a sound library; I want to type what I
hear in my head and get a wav back. If it's wrong I'll iterate
on the prompt. This is the first stop."
User story (musician sketching ideas):
"I want to bounce a 30s lo-fi drum loop to use as a placeholder
bed while I build the rest of the track. Type prompt, get audio,
drop into the DAW. The actual production beat I'll record
myself, but I need *something* to write the chords against."
User story (researcher exploring the model):
"First time touching Stable Audio Open — what does it sound
like at default settings? This is the smallest amount of code
that goes from prompt to mp4."
How it works:
Pure text-to-audio (T2A). The pipeline runs:
T5 + NumberConditioner -> StableAudioDiT -> Oobleck VAE
via the `dpmpp-3m-sde` k-diffusion sampler. All components are
FastVideo-native — no diffusers / transformers model imports at
runtime (see REVIEW item 30). Mirrors upstream
`stable_audio_tools.inference.generation.generate_diffusion_cond`
bit-for-bit (~0.2% abs_mean drift on 25 steps).
Tunable knobs (the "creative dials"):
audio_end_in_s
1–6 — quick ideation (sub-10s wall clock at 100 steps)
10–30 — full musical phrase / loop length (the README example
uses 30s)
47.5 — model maximum (full sample_size = 2097152 / 44100 Hz)
num_inference_steps
25 — fast preview, occasional artifacts
100 — preset default (matches the HF model card)
250 — diminishing returns past here
guidance_scale
3 — looser, more variation per seed
7 — preset default; matches README
12+ — sharper but can sound "fried"
Prerequisites:
1. Accept the terms on https://huggingface.co/stabilityai/stable-audio-open-1.0
and export your HF token in the shell:
export HF_TOKEN=hf_...
2. Install optional inference deps (one-time):
uv pip install k_diffusion einops_exts alias_free_torch torchsde
"""
from fastvideo import VideoGenerator
PROMPT = "Lo-fi hip hop instrumental with vinyl crackle and gentle piano."
def main() -> None:
generator = VideoGenerator.from_pretrained(
"FastVideo/stable-audio-open-1.0-Diffusers",
{
"engine": {
"num_gpus": 1,
},
},
)
output_path = "outputs_audio/stable_audio_basic/output_stable_audio.wav"
generator.generate({
"prompt": PROMPT,
"output": {
"output_path": output_path,
"save_video": True,
},
"extensions": {
# 6-second clip; the model max is ~47.5s.
"audio_end_in_s": 6.0,
},
# The registered preset gives 100 steps + CFG=7.0 by default;
# override num_inference_steps / guidance_scale here for QA.
})
generator.shutdown()
if __name__ == "__main__":
main()