Why do some VFBC layers fail to appear on the XSVI output interface?
For example, given four VFBC layers, you can see that all four of the layers are read out of the four VFBC ports by the Video On Screen Display (OSD), but that only two of the layers data are posted onto the XSVI output interface, even when all four VFBC layers are enabled. It appears that for VFBC0 and VFBC2, the OSD can read data and put the data onto the XSVI interface, but for VFBC1 and VFBC3 the OSD reads that data, but the data is not posted to the XSVI output interface.
There are several controls to ensure that the layers are properly output from the OSD core.
If the layers are not enabled or have the same priority, you might see the behavior described above where some of the layers are not posted onto the XSVI output interface.
For a detailed list of LogiCORE IP Video On Screen Display Release Notes and Known Issues, see (Xilinx Answer 33257).