# V1 API

FastVideo's V1 API provides a streamlined interface for video generation tasks with powerful customization options. This page documents the primary components of the API.

## Video Generator

This class will be the primary Python API for generating videos and images.

<api-reference path="fastvideo.entrypoints.video_generator.VideoGenerator" heading="3" members="from_pretrained" />
`VideoGenerator.from_pretrained()` should be the primary way of creating a new video generator.

## Configuring FastVideo

The following two classes `PipelineConfig` and `SamplingParam` are used to configure initialization and sampling parameters, respectively.

### PipelineConfig

<api-reference path="fastvideo.configs.pipelines.base.PipelineConfig" heading="4" members="from_pretrained,dump_to_json" />
### SamplingParam

<api-reference path="fastvideo.api.sampling_param.SamplingParam" heading="4" members="from_pretrained" />
### Returning samples without previews

Set `OutputConfig(return_samples=True, return_frames=False, save_video=False)`
to receive the decoded CPU tensor in `GenerationResult.samples` without building
preview grids or writing media. Pixel samples retain the existing float `[0, 1]`
contract. `return_frames=True` continues to return both samples and preview frames.
The legacy sampling/keyword interface accepts the same `return_samples` option.

### Choosing an output filename

Set `request.output.output_video_name` to choose a filename when
`request.output.output_path` is a directory:

```python
result = generator.generate({
    "prompt": "A waterfall in the mountains",
    "output": {"output_path": "outputs/", "output_video_name": "my_clip"},
})
# Saves outputs/my_clip.mp4 when that file does not already exist.
```

An explicit file path such as `outputs/custom.mp4` takes precedence over
`output_video_name`. Without a name, the filename is derived from the prompt
(or the input video for prompt-less super-resolution pipelines). Names are
sanitized, and existing files are preserved by adding numeric suffixes such as
`my_clip_1.mp4`, including when processing multiple prompts. A matching extension
in the name is not duplicated. Image workloads accept PNG, JPEG, or WebP names
and default to PNG; audio workloads use WAV.

For requests that save media, the sanitized filename is checked against the
destination filesystem's filename byte limit, including its extension and any
collision suffix. If the limit cannot be determined, 255 bytes is used.
Overlong names are rejected before model execution; use a shorter name rather
than relying on automatic truncation. Multibyte characters may use more than
one byte each. Prompt-file batches retain their existing per-prompt error
handling.

Requests with `save_video=False` or `output_type="latent"` do not prepare an
output file: filename validation, directory creation, and collision checks are
skipped. This also applies to latent output when `save_video=True`.

The legacy `SamplingParam` and `generate_video` keyword interfaces accept the
same `output_video_name` option.