Getting Images From Clips

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...

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.

  • it is an error for a plugin to attempt random temporal image access if the host does not support it
  • it is an error for a plugin to attempt random temporal image access if it has not flagged that it wishes to do so and the clip it wishes to do so from.