Clips in instances are retrieved via the
OfxImageEffectSuiteV1::clipGetHandle
function. This returns a property handle for the clip in a specific instance. This handle is valid for the duration of the instance.
Images are fetched from a clip via the
OfxImageEffectSuiteV1::clipGetImage
function. This takes a time and an optional region to extract an image at from a given clip. This returns, in a property handle, an image fetched from the clip at a specfic time. The handle contains all the information relevant to dealing with that image.
Once fetched, an image must be released via the
OfxImageEffectSuiteV1::clipReleaseImage
function. All images must be released within the action they were fetched in. You cannot retain an image after an action has returned.
Images may be fetched from an attached clip in the following situations...
kOfxImageEffectActionRender
action
kOfxActionInstanceChanged
and
kOfxActionEndInstanceChanged
actions with a
kOfxPropChangeReason
of
kOfxChangeUserEdited
A host may not be able to support random temporal access, it flags its ability to do so via the
kOfxImageEffectPropTemporalClipAccess
property. A plugin that wishes to perform random temporal access must set a property of that name on the plugin handle and the clip it wishes to perform random access from.