ref_iface_IVDXVideoSource_IsKey - shekh/VirtualDub2 GitHub Wiki

VirtualDub Plugin SDK 1.2

IVDXVideoSource interface

IVDXVideoSource:: IsKey

Returns true if the sample corresponds to a key frame, false otherwise.

bool IsKey(sint64 sample_num);

Parameters

sample_num	Number of sample being queried.

Thread safety

This method is not thread-safe.

Errors

Errors may not be returned from this function (see SetError()).

Remarks

The result of IsKey() should be consistent between calls for the same sample, and with the information returned by GetSampleInfo().

For a video source that follows the traditional AVI predictive model, this function returns true for a key frame and false for a delta frame or null frame. The first frame in the source should always be a key frame.

Video sources that use bidirectional prediction, such as MPEG-1/2, should return true for an I frame and false for P and B frames.

When using the default I/P decoder model, IsKey() is called frequently.