mlt_properties_set_double( properties, "movit.parms.vec4.factor[0]", opacity );
mlt_properties_set_double( properties, "movit.parms.vec4.factor[1]", opacity );
mlt_properties_set_double( properties, "movit.parms.vec4.factor[2]", opacity );
mlt_properties_set_double( properties, "movit.parms.vec4.factor[0]", opacity );
mlt_properties_set_double( properties, "movit.parms.vec4.factor[1]", opacity );
mlt_properties_set_double( properties, "movit.parms.vec4.factor[2]", opacity );