How to konw what size a blank DVD disk is?

i am working a DVD brun program with NeroAPI, and there is a puzzling problem which blocks my progress.
that is how to konw how many Bytes when insert a blank DVD disk. i use the NeroGetCDInfo to grab disk info. and can get some info like following:

>Total Capacity:2298496<br>
>Unused Blocks:0<br>
>Medium Flags:<br>

as showed above, NeroGetCDInfo can return total capacity in block unit. but how can i get size in byte unit? i don’t know what size is one block.

by the way, when I check disk by using “Nero InfoTool”, it can recognize disk capacity as 4.38GB. i wonder how it can get this. anyone konws? give a hand plz. :confused:

One logical block size is 2048 bytes.

Is there anyone can tell me, please, how to get FreeCapacityInBlocks and that’s it. Or in Bytes. I’m not C programmer. Is it possible to get this info using Nero or other products?

I mean number and there should be no other info.

The size of a DVD is normally printed on the face of the DVD. Generally 120mins, 4.7GB