Unable to deallocate media - deallocate call failed.

无法解除分配媒体 - 解除分配调用失败.

In general, value types are cheaper to allocate and deallocate;

通常情况下，值类型的内存空间分配和释放的开销较小；

Using singletons makes the design more efficient because they remove the need to allocate and deallocate memory every time a state change is made.

使用单件使得这一设计更加高效，因为避免了在每一次状态转换的时候申请和释放内存。