Understanding pipeline architecture

Pipelines are the core abstraction for handling streaming video in Scope. A pipeline encapsulates model loading, inference logic, configuration schemas, and metadata.

Pipeline Definition

The Pipeline Base Class

All pipelines inherit from the abstract Pipeline class:

from abc import ABC, abstractmethod

class Pipeline(ABC):
    @classmethod
    def get_config_class(cls) -> type["BasePipelineConfig"]:
        """Return the Pydantic config class for this pipeline."""
        ...

    @abstractmethod
    def __call__(self, **kwargs) -> dict:
        """Process video frames and return results."""
        pass

Method	Purpose
`get_config_class()`	Returns the Pydantic config class that defines parameters and metadata
`__call__()`	Processes input frames and returns generated video

Configuration Schema

Every pipeline defines a Pydantic configuration class that inherits from BasePipelineConfig. This class serves as the single source of truth for:

Pipeline metadata (ID, name, description, version)
Feature flags (LoRA support, VACE support, quantization)
Parameter definitions with validation constraints
UI rendering hints for the frontend

Example Configuration

from pydantic import Field
from scope.core.pipelines.base_schema import BasePipelineConfig, ModeDefaults, ui_field_config

class LongLiveConfig(BasePipelineConfig):
    # Metadata (class variables)
    pipeline_id = "longlive"
    pipeline_name = "LongLive"
    pipeline_description = "A streaming autoregressive video diffusion model..."
    estimated_vram_gb = 20.0
    supports_lora = True
    supports_vace = True

    # Parameters (instance fields with validation)
    height: int = Field(
        default=320,
        ge=1,
        description="Output height in pixels",
        json_schema_extra=ui_field_config(
            order=4, component="resolution", is_load_param=True
        ),
    )

    noise_scale: float = Field(
        default=0.7,
        ge=0.0,
        le=1.0,
        description="Amount of noise to add during video generation",
        json_schema_extra=ui_field_config(
            order=7, component="noise", modes=["video"], is_load_param=True
        ),
    )

Pipeline Metadata

Configuration classes declare metadata as class variables:

Metadata	Type	Description
`pipeline_id`	`str`	Unique identifier used for registry lookup
`pipeline_name`	`str`	Human-readable display name
`pipeline_description`	`str`	Description of capabilities
`pipeline_version`	`str`	Semantic version string
`docs_url`	`str \| None`	Link to pipeline documentation
`estimated_vram_gb`	`float \| None`	Estimated VRAM requirement in GB
`artifacts`	`list[Artifact]`	Model files required by the pipeline

Feature Flags

Feature flags control which UI controls are shown:

Flag	Effect
`supports_lora`	Enables LoRA management UI
`supports_vace`	Enables VACE reference image UI
`supports_cache_management`	Enables cache controls
`supports_quantization`	Enables quantization selector
`supports_kv_cache_bias`	Enables KV cache bias slider

Artifacts

Artifacts declare model files and resources that a pipeline requires. The system downloads these automatically before the pipeline loads.

Available Artifact Types

Type	Source	Attributes
`HuggingfaceRepoArtifact`	HuggingFace Hub	`repo_id`, `files`
`GoogleDriveArtifact`	Google Drive	`file_id`, `files` (optional), `name` (optional)

Example

from scope.core.pipelines.artifacts import HuggingfaceRepoArtifact, GoogleDriveArtifact

class MyPipelineConfig(BasePipelineConfig):
    pipeline_id = "my-pipeline"

    artifacts = [
        HuggingfaceRepoArtifact(
            repo_id="depth-anything/Video-Depth-Anything-Small",
            files=["video_depth_anything_vits.pth"],
        ),
        GoogleDriveArtifact(
            file_id="1Smy6gY7BkS_RzCjPCbMEy-TsX8Ma5B0R",
            files=["flownet.pkl"],
            name="RIFE",
        ),
    ]

Common artifacts shared across pipelines can be reused:

from scope.core.pipelines.common_artifacts import WAN_1_3B_ARTIFACT, VACE_ARTIFACT

class MyPipelineConfig(BasePipelineConfig):
    artifacts = [WAN_1_3B_ARTIFACT, VACE_ARTIFACT]

Input Requirements

The prepare() method declares input frame requirements before processing. Pipelines that accept video input must implement it.

Return Value	Meaning
`Requirements(input_size=N)`	Pipeline needs N input frames before `__call__()`
`None`	Pipeline operates in text-only mode (no video input needed)

Example

from scope.core.pipelines.interface import Requirements

class MyPipeline(Pipeline):
    def prepare(self, **kwargs) -> Requirements:
        return Requirements(input_size=4)

    def __call__(self, **kwargs) -> dict:
        video = kwargs.get("video")  # List of 4 frames
        # ... process video ...

Multi-mode Pipeline Example

Pipelines that support both text-to-video and video-to-video modes use the prepare_for_mode() helper from defaults.py:

from scope.core.pipelines.defaults import prepare_for_mode
from scope.core.pipelines.interface import Requirements

class LongLivePipeline(Pipeline):
    def prepare(self, **kwargs) -> Requirements | None:
        """Return input requirements based on current mode."""
        return prepare_for_mode(self.__class__, self.components.config, kwargs)

The helper returns Requirements when video mode is active (indicated by video=True in kwargs) and None for text mode. The input_size is calculated from the pipeline’s configuration. Why implement prepare():

Without it, the frame processor cannot know how many frames to buffer before calling __call__()
Enables efficient queue management - the processor sizes queues based on requirements
Allows multi-mode pipelines to dynamically switch between text and video input modes

Mode System

Pipelines can support multiple input modes with different default parameters:

class LongLiveConfig(BasePipelineConfig):
    # Base defaults
    height: int = Field(default=320, ...)
    width: int = Field(default=576, ...)

    # Mode-specific overrides
    modes = {
        "text": ModeDefaults(default=True),
        "video": ModeDefaults(
            height=512,
            width=512,
            noise_scale=0.7,
        ),
    }

Mode	Description
`text`	Text-to-video generation from prompts only
`video`	Video-to-video with input conditioning

The default=True flag marks which mode is selected initially.

Preprocessors and Postprocessors

Pipelines can be declared as preprocessors or postprocessors using the usage class variable:

from scope.core.pipelines.base_schema import BasePipelineConfig, ModeDefaults, UsageType

class MyPreprocessorConfig(BasePipelineConfig):
    pipeline_id = "my-preprocessor"
    pipeline_name = "My Preprocessor"
    usage = [UsageType.PREPROCESSOR]

    modes = {"video": ModeDefaults(default=True)}

Type	Purpose	UI Location
`UsageType.PREPROCESSOR`	Process input video before main pipeline	Preprocessor dropdown
`UsageType.POSTPROCESSOR`	Process output video after main pipeline	Postprocessor dropdown
(empty list)	Standard pipeline	Main pipeline selector

Dynamic UI Rendering

JSON Schema Generation

Pydantic models automatically generate JSON Schema via model_json_schema(). The backend exposes this schema through the /pipelines endpoint, which the frontend consumes for dynamic UI rendering. The schema includes:

Field types and validation constraints (minimum, maximum, enum)
Default values
Descriptions (used as tooltips)
Custom UI metadata (via json_schema_extra)

Schema-to-UI Flow

Backend (Python)                    Frontend (React)
─────────────────                   ─────────────────
BasePipelineConfig
       │
       ▼
model_json_schema()
       │
       ▼
GET /pipelines  ───────────────────▶  configSchema
                                           │
                                           ▼
                                    parseConfigurationFields()
                                           │
                                           ▼
                                    Field type inference
                                           │
                                    ┌──────┴──────┐
                                    ▼             ▼
                              Primitive      Complex
                              widgets        components

Field Type Inference

For fields without a component specified, the frontend automatically renders an appropriate widget based on the JSON Schema type. The frontend (schemaSettings.ts) infers widget types from schema properties:

Schema Property	Inferred Type	Widget
`type: "boolean"`	`toggle`	Toggle switch
`type: "string"`	`text`	Text input
`type: "number"` with `minimum`/`maximum`	`slider`	Slider with input
`type: "number"` without bounds	`number`	Number input
`enum` or `$ref`	`enum`	Select dropdown

Two-Tier Component System

The UI uses a two-tier approach: primitive fields render as individual widgets based on inferred type, while complex components group related fields into unified UI blocks.

UI Metadata

The ui_field_config() helper attaches rendering hints to schema fields:

height: int = Field(
    default=320,
    ge=1,
    description="Output height in pixels",
    json_schema_extra=ui_field_config(
        order=4,              # Display order (lower = higher)
        component="resolution", # Complex component grouping
        is_load_param=True,   # Requires pipeline reload
        modes=["video"],      # Only show in video mode
        label="Height",       # Short label
        category="configuration", # Panel placement
    ),
)

Field	Type	Description
`order`	`int`	Sort order for display (lower values appear first)
`component`	`str`	Groups fields into complex widgets (e.g., “resolution”, “noise”)
`modes`	`list[str]`	Restrict visibility to specific input modes
`is_load_param`	`bool`	If `True`, field is disabled during streaming
`label`	`str`	Short display label; description becomes tooltip
`category`	`str`	`"configuration"` for Settings panel, `"input"` for Input & Controls

Complex Components

Fields with the same component value are grouped and rendered together:

Component	Fields	Rendered As
`resolution`	`height`, `width`	Linked dimension inputs
`noise`	`noise_scale`, `noise_controller`	Slider + toggle
`vace`	`vace_context_scale`	VACE configuration panel
`lora`	`lora_merge_strategy`	LoRA manager
`denoising_steps`	`denoising_steps`	Multi-step slider

Fields with the same component value are grouped and rendered once.

Mode-Aware Filtering

Fields specify which modes they appear in via modes:

noise_scale: float = Field(
    ...,
    json_schema_extra=ui_field_config(modes=["video"]),
)

The frontend filters fields based on the current input mode, hiding irrelevant controls.

Load-time vs Runtime Parameters

Type	`is_load_param`	Editable During Streaming	Example
Load parameter	`True`	No	Resolution, quantization, seed
Runtime parameter	`False`	Yes	Prompt strength, noise scale

Load parameters are passed when the pipeline loads and require a restart to change. Runtime parameters can be adjusted while streaming.

Pipeline Registry

Pipelines register with the central PipelineRegistry at startup:

from scope.core.pipelines.registry import PipelineRegistry

PipelineRegistry.register(config_class.pipeline_id, pipeline_class)

Built-in vs Node Pipelines

Built-in pipelines are registered automatically when the registry module is imported. Node pipelines register through the pluggy hook system:

from scope.core.plugins.hookspecs import hookimpl

@hookimpl
def register_pipelines(register):
    from .pipelines import MyCustomPipeline
    register(MyCustomPipeline)

GPU-Based Filtering

Pipelines with estimated_vram_gb set are only registered if a compatible GPU is detected. This prevents showing pipelines that cannot run on the current hardware.

Developing Nodes

Create your own custom pipelines

Node Architecture

Technical details of the node system

Getting Started

Tutorials

Guides

API Reference

Pipelines

Reference

Concepts

Pipeline Architecture

Understanding pipeline architecture

Pipeline Definition

The Pipeline Base Class

Configuration Schema

Example Configuration

Pipeline Metadata

Feature Flags

Artifacts

Available Artifact Types

Example

Input Requirements

Example

Multi-mode Pipeline Example

Mode System

Preprocessors and Postprocessors

Dynamic UI Rendering

JSON Schema Generation

Schema-to-UI Flow

Field Type Inference

Two-Tier Component System

UI Metadata

Complex Components

Mode-Aware Filtering

Load-time vs Runtime Parameters

Pipeline Registry

Built-in vs Node Pipelines

GPU-Based Filtering

See Also

Developing Nodes

Node Architecture

Getting Started

Tutorials

Guides

API Reference

Pipelines

Reference

Concepts

Documentation Index

​Understanding pipeline architecture

​Pipeline Definition

​The Pipeline Base Class

​Configuration Schema

​Example Configuration

​Pipeline Metadata

​Feature Flags

​Artifacts

​Available Artifact Types

​Example

​Input Requirements

​Example

​Multi-mode Pipeline Example

​Mode System

​Preprocessors and Postprocessors

​Dynamic UI Rendering

​JSON Schema Generation

​Schema-to-UI Flow

​Field Type Inference

​Two-Tier Component System

​UI Metadata

​Complex Components

​Mode-Aware Filtering

​Load-time vs Runtime Parameters

​Pipeline Registry

​Built-in vs Node Pipelines

​GPU-Based Filtering

​See Also

Developing Nodes

Node Architecture

Understanding pipeline architecture

Pipeline Definition

The Pipeline Base Class

Configuration Schema

Example Configuration

Pipeline Metadata

Feature Flags

Artifacts

Available Artifact Types

Example

Input Requirements

Example

Multi-mode Pipeline Example

Mode System

Preprocessors and Postprocessors

Dynamic UI Rendering

JSON Schema Generation

Schema-to-UI Flow

Field Type Inference

Two-Tier Component System

UI Metadata

Complex Components

Mode-Aware Filtering

Load-time vs Runtime Parameters

Pipeline Registry

Built-in vs Node Pipelines

GPU-Based Filtering

See Also