Specifying Pixel Aspect Ratios

Hosts and plugins flag whether whether they can deal with input/output clips of differing pixel aspect ratios via the kOfxImageEffectPropSupportsMultipleClipPARs property.

If the host sets this to 0, then all effect's input and output clips will always have the same pixel aspect ratio, and the plugin may not remap them.

If the plugin sets this to 0, then the host will transparently map all of an effect's input and output clips to a single pixel aspect ratio, even if the actual clips are of differring PARs.

In the above two cases, the common pixel aspect ratio chosen will be the smallest on all the inputs, as this preserves image data.

If both the plugin and host set this to 1, then the plugin can, during kOfxImageEffectActionGetClipPreferences , specify how the host is to map each clip, including the output clip.