Choosing a HAP variant trades alpha support and colour fidelity against data-rate

HAP defines several named variants distinguished by their texture format. The choice is a practical tradeoff a VJ makes per clip. Plain Hap (RGB DXT1/BC1) is smallest and has no transparency. Hap Alpha (RGBA DXT5/BC3) adds an alpha channel for overlays and logos. Hap Q (Scaled YCoCg DXT5/BC3) gives noticeably better colour fidelity at a higher data-rate, and Hap Q Alpha adds transparency on top of that. Specialist variants (Hap Alpha-Only, Hap R using BC7, Hap HDR using BC6) cover HDR and alpha-only cases. The decision hinges on two questions: does the clip need transparency, and is colour fidelity worth the extra storage bandwidth? VJs typically reach for Hap Q on quality-critical footage and plain Hap to save bandwidth on backgrounds that need neither alpha nor high fidelity.

Examples

A logo sting with a transparent background must be Hap Alpha or Hap Q Alpha. A full-screen background plate needs neither transparency nor top colour fidelity, so plain Hap streams fastest and lets you stack more layers.

Assessment

For a clip that needs a transparent background and one that is an opaque full-screen background, state which HAP variant you would pick for each and justify the choice in terms of alpha support and data-rate.