How do I replace data in a pipeline in DeepStream?

[fanzh]

1. what is the media pipeline? what are the model’s inputs and outputs? here is a sample to modify image data :Deepstream sample code snippet - #3 by bcao

@1017948396

but on a black image with a size of 200×400

2. why is it a black image? the detection models usually give a bonding boxes, which are some coordinates.