Pin回调SetDeviceState

当KSPIN改变状态时，调用该回调。

typedef struct {
  PFNKSPINIRP  Create;
  PFNKSPINIRP  Close;
  PFNKSPIN  Process;
  PFNKSPINVOID  Reset;
  PFNKSPINSETDATAFORMAT  SetDataFormat;
  PFNKSPINSETDEVICESTATE  SetDeviceState; //改变状态
  PFNKSPIN  Connect;
  PFNKSPINVOID  Disconnect;
  const KSCLOCK_DISPATCH*  Clock;
  const KSALLOCATOR_DISPATCH*  Allocator;
} KSPIN_DISPATCH, *PKSPIN_DISPATCH;

设置状态的函数声名为：

NTSTATUS
  AVStrMiniPinSetDeviceState(
    IN PKSPIN  Pin,
    IN KSSTATE  ToState,
    IN KSSTATE  FromState);
    );

对应的状态有4个,而FromState给示的是上一下状态，所以有了状态的切换。

typedef enum {
  KSSTATE_STOP;
  KSSTATE_ACQUIRE;
  KSSTATE_PAUSE;
  KSSTATE_RUN;
} KSSTATE;

• KSSTATE_STOP：最小资源消耗状态
• KSSTATE_ACQUIRE :正在获取资源
• KSSTATE_PAUSE ：正准备运行到KSSTATE_RUN状态。
• KSSTATE_RUN ：正在进行流传输

状态切换

打开相机时

CCapturePin::SetState FromState:KSSTATE_STOP ———> ToState:KSSTATE_ACQUIRE
CCapturePin::SetState FromState:KSSTATE_ACQUIRE ———> ToState:KSSTATE_PAUSE
CCapturePin::SetState FromState:KSSTATE_PAUSE ———> ToState:KSSTATE_RUN

从工作到暂停时：

CCapturePin::SetState FromState:KSSTATE_RUN ———> ToState:KSSTATE_PAUSE

从暂停时到恢复运行：

CCapturePin::SetState FromState:KSSTATE_PAUSE ———> ToState:KSSTATE_RUN

从暂停时到停止：

CCapturePin::SetState FromState:KSSTATE_PAUSE ———> ToState:KSSTATE_ACQUIRE
CCapturePin::SetState FromState:KSSTATE_ACQUIRE ———> ToState:KSSTATE_STOP
Cleanup CCapturePin
~CCapturePin
Cleanup CCaptureFilter

从工作到停止：

CCapturePin::SetState FromState:KSSTATE_RUN ———> ToState:KSSTATE_PAUSE
CCapturePin::SetState FromState:KSSTATE_PAUSE ———> ToState:KSSTATE_ACQUIRE
CCapturePin::SetState FromState:KSSTATE_ACQUIRE ———> ToState:KSSTATE_STOP

Cleanup CCapturePin
~CCapturePin
Cleanup CCaptureFilter

总结

• KSSTATE_STOP ：就是停止
• KSSTATE_ACQUIRE：从STOP到KSSTATE_ACQUIRE ，就要创建资源，为准备打开。从PAUSE到ACQUIRE可以释放资源
• KSSTATE_RUN：工作之前必是KSSTATE_PAUSE