Libavfilter
The libavfilter library provides a generic audio/video filtering framework containing several filters, sources and sinks.
lavfi
Libavfilter input virtual device.
This input device reads data from the open output pads of a libavfilter filtergraph.
For each filtergraph open output, the input device will create a corresponding stream which is mapped to the generated output. The filtergraph is specified through the option graph.
FFmpeg 에서 샘플 영상 만드는 방법
FFmpeg:CLI#테스트 영상 생성 항목 참조.