Otherwise sm_size can be larger than size, which results in a negative
packet size.
Reviewed-by: Michael Niedermayer <michaelni@gmx.at>
Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com>
(cherry picked from commit 6b9fdf7f)
Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com>