struct Context {
    virtual ~Context() = default;
};
struct VideoContext : public Context {};
struct AudioContext : public Context {};

struct VideoContextA1 : public VideoContext {
    int mA;
    float mB;
};

struct VideoContextA2 : public VideoContext {
    int mC;
    float mD;
};

class A {
    virutal int foo(Context* context) = 0;
};

class A1 : public A {
    int foo(Context* context) override {
        // dynamic cast
        auto* ctx = dynamic_cast<VideoContextA1*>(context);
        // .... bla bla bla
    }
};

class A2 : public A {
    int foo(Context* context) override {
        // dynamic cast
        auto* ctx = dynamic_cast<VideoContextA2*>(context);
        // .... bla bla bla
    }
};