39.6.3.4 Overlay Blender Attributes

When two or more video layers are used, alpha blending is performed to define the final image displayed. Each window has its own blending attributes.

  • CRKEY bit—Enables the chroma keying and match logic.
  • INV bit—Performs bit inversion at pixel level.
  • ITER2BL bit—When written to ‘1’, the iterated data path is selected.
  • ITER bit—When written to ‘1’, the iterated value is used in the iterated data path, otherwise the iterated value is set to 0.
  • REVALPHA bit—Uses the reverse alpha value.
  • GAEN bit—Enables the global alpha value in the data path.
  • LAEN bit—Enables the local alpha value from the pixel.
  • OVR bit—When written to ‘1’, the overlay is selected as an input of the blender.
  • DMA bit—The DMA data path is activated.
  • REP bit—Enables the bit replication to fill the 24-bit internal data path.
  • DSTKEY bit—When written to ‘1’, Destination keying is enabled.
  • GA field—Defines the global alpha value.