Pipeline internals

The stage interface is quite simple. Each stage acts as an iterator, typically yielding some kind of pose bundle. A pose bundle is an iterator of skeletons, either with ids or not depending on whether it has been tracked.

Each stage inherits from the PipelineStageBase abstract base class which includes also send_back to send back events to earlier stages in the pipeline.

skelshop.pipebase.PipelineStageBase

The abstract base class for a pipeline stage.

__next__(self) special

Get the payload for the next frame

Source code in skelshop/pipebase.py

@abstractmethod
def __next__(self):
    """
    Get the payload for the next frame
    """
    ...

send_back(self, name, *args, **kwargs)

Send a message back down the pipeline by calling a method with name, *args, and `*kwargs

Source code in skelshop/pipebase.py

def send_back(self, name: str, *args, **kwargs):
    """
    Send a message back down the pipeline by calling a method with `name`,
    `*args`, and `*kwargs
    """
    meth = getattr(self, name, None)
    if meth is not None:
        meth(*args, **kwargs)
        return
    if self.prev is not None:
        self.prev.send_back(name, *args, **kwargs)

Events types in use through send_back

Currently cut event is sent back by any shot segmentation stage to the tracking stage, so that tracking can be reset. Each stage is free to deal with events as it wishes, e.g. a tracking stage attempting to track across shots could react differently to this event.

A rewind event can be sent back so that a RewindStage will reverse a given number of frames in its buffer. Note that you must arrange for a RewindStage to be placed into the pipeline.