Free space problem with multisession


how can I determine the amount of data which can burn on a CD (exact as possible)?

If I burn multisession cds for every session a seperate leadin/out is written, which have a size of 11400 blocks(~23 MB) for the second session and 6900 blocks(~14 MB) for every further session (as far as NeroGetCDInfo reports this gaps between the sessions). This gaps between the sessions are not so small to ignore them.

NeroGetCDInfo returns in the ncdiFreeCapacityInBlocks member of the NERO_CD_INFO structure, an amount of free blocks. Is this the free space for data or must I reduce this value with the block amount for leadin/out? If I must reduce the value, which space should I calculate for leadin/out?

If I have a data set for the next session, I can calculate the space for it with NeroEstimateTrackSize(…) with NETS_EXCAT_SIZE. Can I assume the session fits on CD, if this value is smaller then ncdiFreeCapacityInBlocks or must I calculate additional space for leadin/out?