lavfi/pan: switch to AVFrame.
lavfi/silencedetect: switch to AVFrame.
lavfi/showspectrum: switch to AVFrame.
lavfi/ebur128: switch to AVFrame.
lavfi/edgedetect: switch to AVFrame.
lavfi/geq: switch to AVFrame.
lavfi/pp: switch to AVFrame.

Note: qp not honored anymore...
lavfi/subtitles: switch to AVFrame.
lavfi/thumbnail: switch to AVFrame.