IAMVideoCompression::get_PFramesPerKeyFrame (Compact 2013)

3/26/2014

This method retrieves the rate of predicted (P) frames per key frame.

Syntax

HRESULT get_PFramesPerKeyFrame(
  long* pPFramesPerKeyFrame
);

Parameters

• pPFramesPerKeyFrame
  [out] Pointer to a long variable that receives the number of P frames per key frame. If the value is negative, the filter will use the default rate.

Return Value

Returns an HRESULT value.

Remarks

To determine if the filter supports this method, call the IAMVideoCompression::GetInfo method and check for the CompressionCaps_CanBFrame (see CompressionCaps) flag in the pCapabilities parameter. The GetInfo method also returns the default P-frame rate.

P frames are used in MPEG compression; in general, this property does not apply to other compression formats. For example, suppose a key frame occurs once every 10 frames, and there are three P frames per key frame. The P frames will be spaced evenly between the key frames. The remaining six frames are bidirectional (B) frames.

Requirements

See Also

Reference

IAMVideoCompression Interface
IAMVideoCompression::put_KeyFrameRate
IAMVideoCompression::GetInfo
CompressionCaps