Remove unnecessary inlines

Signed-off-by: Claudio Matsuoka <cmatsuoka@gmail.com>
Fix sample range when downmixing

When downmixing to unsigned samples, apply offset to limited values.

Signed-off-by: Claudio Matsuoka <cmatsuoka@gmail.com>
Update changelog

Signed-off-by: Claudio Matsuoka <cmatsuoka@gmail.com>