avfilter/idet: add metadata to "current" frame instead of "next" frame

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avfilter/idet: add current frame classification to metadata

Fixes ticket 3832

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avformat/assenc: Add ignore_gaps option

Signed-off-by: Clément Bœsch <u@pkh.me>
avformat: add webp muxer

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/libwebpenc: support "P" frames in webp animations

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>