ref_struct_VDXFilterStateInfo - shekh/VirtualDub2 GitHub Wiki

VirtualDub Plugin SDK 1.2

VDXFilterStateInfo structure

Reflects the video pipeline state while a video filter is active.

struct VDXFilterStateInfo {
    sint32  lCurrentFrame;
    sint32  lMicrosecsPerFrame;
    sint32  lCurrentSourceFrame;
    sint32  lMicrosecsPerSrcFrame;
    sint32  lSourceFrameMS;
    sint32  lDestFrameMS;

    enum {
        kStateNone      = 0x00000000,
        kStatePreview   = 0x00000001,
        kStateRealTime  = 0x00000002,
        kStateMax       = 0xFFFFFFFF
    };

    uint32  flags;
    sint32  mOutputFrame;
};

lCurrentFrame
The frame number of the current frame being produced by the video filter, starting at zero.

lMicrosecsPerFrame
Approximate frame rate of the destination video stream, in microseconds per frame.

lCurrentSourceFrame
The frame number of the current source frame being processed by the video filter, starting at zero. This is useful for associating data that must be tracked with the source, such as field order and subtitling data. The frame number sequence need not be sequential; gaps in the frame sequence reflect where portions of the source may have been omitted from processing. It is also possible for source numbers to be duplicated when the source is resampled to a higher frame rate prior to the filter.

lMicrosecsPerSrcFrame
Approximate frame rate of the source video stream, in microseconds per frame.

lSourceFrameMS
Starting time of the source video frame, in milliseconds. Note that this is not simply the same as combining lCurrentSourceFrame and lMicrosecsPerSrcFrame, as the host can internally use a higher precision value in computing this field.

lDestFrameMS
Starting time of the destination video frame, in milliseconds. Note that this is not simply the same as combining lCurrentFrame and lMicrosecsPerFrame, as the host can internally use a higher precision value in computing this field.

flags
(V10+ only) A bitfield with the following flags:

kStatePreview
Set when the filter chain is being run for preview purposes only, such as when scrubbing through the timeline or previewing the output; cleared when the processed video is saved or an analysis pass is running. If your filter records data about the video or otherwise expects a full pass through it, you should suppress that action when this flag is set.

kStateRealTime
Set when the filter chain is being run in a situation with real-time constraints, such as preview or capture mode. A filter might switch to a different algorithm when this flag is present.

mOutputFrame
(V13+ only)

Frame number of the output, in the transformed sequence produced by the filter. The prefetchProc method maps each output frame to a source frame. When prefetchProc is omitted, therefore, lCurrentSourceFrame and mOutputFrame will be the same.

The main differences between lDestFrameMS and mOutputFrame have to do with editing and frame rate changing filters. lDestFrame counts up sequentially for each frame and is the same for all filters in the pipeline, regardless of whether there are frame rate doublers or editing involved. mOutputFrame, on the other hand, indicates frame numbers for frames just after they are produced by the filter, before they are reordered by editing or downstream prefetchProc routines.

Copyright (C) 2007-2012 Avery Lee.