Files
hao-ai-lab-FastVideo/docs/inference/configuration.md
T
Davids048andClaude Opus 5.5 4117696a4f [refactor]: describe and use the resolved config in docs, examples, and local tests
- Docs, AGENTS.md files, and skills describe ResolvedGeneratorConfig,
  resolve_inference_config, typed YAML, and --config plus dotted
  overrides for training and preprocessing instead of FastVideoArgs and
  flat flags.
- The local tests build resolved configs (or small fakes that expose typed
  paths) instead of FastVideoArgs; the LoRA extraction scripts build
  pipelines with from_pretrained(model_path, resolved_config=...).
- The mixkit README's NVFP4 snippet uses from_config with
  engine.quantization.transformer_quant (the from_pretrained keyword it
  used is rejected).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012M91wnVFmPEvJ9h39r5BH7
2026-10-03 06:16:10 +00:00

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4.5 KiB
Markdown

# Configuration
## Multi-GPU Setup
FastVideo automatically distributes the generation process when multiple GPUs are specified:
```python
# Will use 4 GPUs in parallel for faster generation
generator = VideoGenerator.from_pretrained(
"Wan-AI/Wan2.1-T2V-1.3B-Diffusers",
num_gpus=4,
)
```
One node uses the multiprocessing executor (`execution_backend: mp`, the
default). Two machines — for example two DGX Sparks, one GPU each — need Ray:
```yaml
generator:
engine:
num_gpus: 2
execution_backend: ray
parallelism:
sp_size: 2
```
Set `RAY_ADDRESS` and `FASTVIDEO_HOST_IP` to the interconnect IPs, not Wi-Fi.
The FastH3 example selects Ray automatically when `RAY_ADDRESS` is set. Full
bring-up: [Pair two NVIDIA DGX Sparks](../getting_started/installation/spark_pair.md).
## Customizing Generation
`VideoGenerator.from_pretrained` accepts only common engine and offload
keywords, such as `num_gpus` and `dit_cpu_offload`. The full list is
`fastvideo.api.compat.FROM_PRETRAINED_KWARGS`. Pass every other startup
setting to `VideoGenerator.from_config` at its config path, and pass
generation settings to `VideoGenerator.generate` as a request:
```python
from fastvideo import VideoGenerator
def main():
model_name = "Wan-AI/Wan2.1-T2V-1.3B-Diffusers"
# Create the generator
generator = VideoGenerator.from_config({
"model_path": model_name,
"engine": {
"num_gpus": 1,
"offload": {"dit_layerwise": True},
"precision": {"vae": "fp16"},
},
})
# Generate video with custom parameters
prompt = "A beautiful sunset over a calm ocean, with gentle waves."
video = generator.generate({
"prompt": prompt,
"sampling": {
# How many frames to generate
"num_frames": 45,
# Video resolution (width, height)
"width": 1024,
"height": 576,
# How many steps we denoise the video (higher = better quality, slower generation)
"num_inference_steps": 30,
# How strongly the video conforms to the prompt (higher = more faithful to prompt)
"guidance_scale": 7.5,
# Random seed for reproducibility
"seed": 42, # Optional, leave unset for random results
},
"output": {
"output_path": "my_videos/", # Controls where videos are saved
"save_video": True,
},
})
# If return_frames=True, frames are available in video.frames
print(f"Generated {len(video.frames)} frames")
if __name__ == '__main__':
main()
```
## JSON/YAML Config Files (CLI)
The inference CLI is config-first. Use an explicit subcommand with `--config`,
then apply optional dotted overrides on top, matching the training CLI style.
By default, CLI generation uses `return_frames=false` unless you set
`request.output.return_frames: true` in config or via a dotted override.
```bash
fastvideo generate --config config.yaml
```
Example nested config:
```yaml
generator:
model_path: FastVideo/FastHunyuan-diffusers
engine:
num_gpus: 2
parallelism:
sp_size: 2
request:
prompt: A capybara relaxing in a hammock
sampling:
num_frames: 45
height: 720
width: 1280
num_inference_steps: 6
seed: 1024
output:
output_path: outputs/
```
Override individual values from the CLI with dotted paths:
```bash
fastvideo generate --config config.yaml --request.sampling.seed 42
```
## Where a Value Came From
FastVideo resolves the generator config once at startup and records the source of every value: the input config
(`input`; `explicit` tells whether you wrote the value or it is the schema default), a `FASTVIDEO_*` environment
variable, the model's defaults, or a derived value. A worker's device policy and values read from checkpoint files
are recorded too.
```python
generator = VideoGenerator.from_config(config)
generator.resolved_config.provenance("engine.parallelism.sp_size")
# PathProvenance(path='engine.parallelism.sp_size', value=2, source='derive_parallel_sizes', ...)
result = generator.generate(request)
result.resolved_request.provenance("sampling.num_frames")
# PathProvenance(..., value=81, source='fill_sampling_defaults[preset wan_t2v_1_3b]', explicit=False)
```
`resolved_config.provenance_table()` lists every path. After startup, `resolved_config` is read-only; a later
change is a recorded override (`resolved_config.with_override(source, values)`) that returns a new object.
## Performance Optimization
For configuring optimizations, please see our [optimizations guide](optimizations.md)