​
Overview

NullFilter is a filtering processor that blocks all frames from passing through, with the exception of system frames and end frames which are required for proper pipeline operation.

​
Constructor Parameters

The NullFilter constructor accepts no specific parameters beyond those inherited from FrameProcessor.

​
Functionality

When a frame passes through the processor:
  • If the frame is a SystemFrame or EndFrame, it is passed through
  • All other frame types are blocked and do not continue through the pipeline
This filter effectively acts as a barrier that allows only the essential system frames required for pipeline initialization, shutdown, and management.

​
Use Cases

NullFilter is useful in several scenarios:
  • Temporarily disabling parts of a pipeline without removing components
  • Creating dead-end branches in parallel pipelines
  • Testing pipeline behavior with blocked communication
  • Implementing conditional pipelines where certain paths should be blocked

​
Usage Example

from pipecat.processors.filters import NullFilter

# Create a null filter that blocks all non-system frames
blocker = NullFilter()

# Add to pipeline
pipeline = Pipeline([
    source,
    blocker,  # Blocks all regular frames
    destination  # Will only receive system frames
])

​
Frame Flow

​
Notes

  • Blocks all regular frames in both directions
  • Only allows system frames and end frames to pass through
  • Useful for testing, debugging, and creating conditional pipelines
  • Minimal overhead as it performs simple type checking
  • Can be used to temporarily disable parts of a pipeline