avfilter/af_asetnsamples: remove .needs_writable as it is not required

Signed-off-by: Paul B Mahol <onemda@gmail.com>
avfilter: remove redundant .get_(audio/video)_buffer initializations

Signed-off-by: Paul B Mahol <onemda@gmail.com>
avfilter/vf_rotate: fix 'oh' option description

Signed-off-by: Paul B Mahol <onemda@gmail.com>
doc: fix install-doc dependencies

Put it inside its own ifdef conditional.

Signed-off-by: James Almer <jamrial@gmail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
doc: rename *install-doc to *install-html

Signed-off-by: James Almer <jamrial@gmail.com>
Reviewed-by: Stefano Sabatini <stefasab@gmail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>