There is a maximum of 32 start registers available that are divided in two register banks, Bank0 and Bank1, each of 16 registers. Both the banks have the same initial offset (that is, 0xAC) and are accessed depending upon the S2MM_REG_INDEX value. If you want to access the 17th start address, it can be done by setting S2MM_REG_INDEX to 1 and accessing offset 0xAC.
When AXI VDMA is configured for an address space greater than 32, a maximum of 16 registers are available. Two registers are used to specify an address that is more than 32 bits. The first register is used to specify LSB 32 bits while the next register is used to specify the MSB 32 bits of any start address.
Therefore with an address space greater than 32 you can specify a maximum of 8 frame buffers, each 64 bits wide.
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X-Ref Target - Figure 2-20 
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|
Bits |
Field Name |
Default Value |
Access Type |
Description |
|---|---|---|---|---|
|
31–0 (Offset 0xAC to 0xE8 max.) |
Start Address 1 to N |
0h |
R/W |
Indicates the Start Address for video buffer 1 to N. |