The default chunk size is 256KiB, if your 60 second is bellow that IPFS is gonna rechunk it in it’s merkle tree.
If you want to be as efficient as possible for IPFS use --raw-leaves and make your chunks about 256KiB, better chunks can be more efficient but it’s at the risk of wasting more bandwidth since chunks can only be transfered whole for now.
You can also up the chunk size with --chunk=size-$NUMBERINBYTES which should be kept under 1MiB for now.