1e41f4b71Sopenharmony_ci# MediaKeySession_Callback 2e41f4b71Sopenharmony_ci 3e41f4b71Sopenharmony_ci 4e41f4b71Sopenharmony_ci## Overview 5e41f4b71Sopenharmony_ci 6e41f4b71Sopenharmony_ciThe MediaKeySession_Callback struct describes the callback used to listen for events such as media key expiry or change, without returning media key session instances. It applies to the scenario where a single media key session needs to be decrypted. 7e41f4b71Sopenharmony_ci 8e41f4b71Sopenharmony_ci**Since**: 11 9e41f4b71Sopenharmony_ci 10e41f4b71Sopenharmony_ci**Related module**: [Drm](_drm.md) 11e41f4b71Sopenharmony_ci 12e41f4b71Sopenharmony_ci 13e41f4b71Sopenharmony_ci## Summary 14e41f4b71Sopenharmony_ci 15e41f4b71Sopenharmony_ci 16e41f4b71Sopenharmony_ci### Member Variables 17e41f4b71Sopenharmony_ci 18e41f4b71Sopenharmony_ci| Name| Description| 19e41f4b71Sopenharmony_ci| -------- | -------- | 20e41f4b71Sopenharmony_ci| [MediaKeySession_EventCallback](_drm.md#mediakeysession_eventcallback) [eventCallback](_drm.md#eventcallback) | Event callback, for example, a media key expiry event.| 21e41f4b71Sopenharmony_ci| [MediaKeySession_KeyChangeCallback](_drm.md#mediakeysession_keychangecallback) [keyChangeCallback](_drm.md#keychangecallback) | Callback of the media key change event.| 22