lavfi: add compand filter

Signed-off-by: Paul B Mahol <onemda@gmail.com>
doc/filters: fix typo

Signed-off-by: Paul B Mahol <onemda@gmail.com>
asfdec: avoid using AVStream->priv_data

This ensures that we dont write into one struct and read the other without
realizing that they arent identical.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
asfdec: move packet_obj_size to ASFStream

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
asfdec: remove "ignoring invalid packet_obj_size" code

The code is no longer needed

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