imediaseeking接口定义了一套标志am_seeking_seeking_capabilities,用来描述可能支持的seek功能。
typedef enum am_seeking_seekingcapabilities { am_seeking_canseekabsolute = 0x1, am_seeking_canseekforwards = 0x2, am_seeking_canseekbackwards = 0x4, am_seeking_cangetcurrentpos = 0x8, am_seeking_cangetstoppos = 0x10, am_seeking_cangetduration = 0x20, am_seeking_canplaybackwards = 0x40, am_seeking_candosegments = 0x80, am_seeking_source = 0x100} am_seeking_seeking_capabilities;
