Microsoft DirectX 8.0

Frame Stepping Property Set

Decoders that implement frame-accurate seeking under Microsoft® DirectShow® must implement the AM_KSPROPSETID_FrameStep property set, which is used in conjunction with the IVideoFrameStep interface. This property set consists of two properties. AM_PROPERTY_FRAMESTEP is used to pass the step commands and stepping-capability information, and AM_FRAMESTEP_STEP is used to specify the number of frames to step.

Syntax

typedef enum {
        AM_PROPERTY_FRAMESTEP_STEP   = 0x01,
        AM_PROPERTY_FRAMESTEP_CANCEL = 0x02,
        AM_PROPERTY_FRAMESTEP_CANSTEP = 0x03,
        AM_PROPERTY_FRAMESTEP_CANSTEPMULTIPLE = 0x04
} AM_PROPERTY_FRAMESTEP;

Members

AM_PROPERTY_FRAMESTEP_STEP
Instructs the decoder to begin a step operation.
AM_PROPERTY_FRAMESTEP_CANCEL
Instructs the decoder to cancel the current step operation.
AM_PROPERTY_FRAMESTEP_CANSTEP
The decoder returns S_OK on this instruction to indicate that it can perform frame stepping, S_FALSE otherwise.
AM_PROPERTY_FRAMESTEP_CANSTEPMULTIPLE
The decoder returns S_OK on this instruction to indicate that it can step multiple frames at a time, S_FALSE otherwise.
typedef struct _AM_FRAMESTEP_STEP
{
    DWORD dwFramesToStep;
} AM_FRAMESTEP_STEP;

AM_FRAMESTEP_STEP Members

dwFramesToStep
DWORD value specifying to the decoder the number of frames to step. Must be at least 1. If greater than one, this instruction means to skip (n - 1) frames and show the nth.