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.