dd question

[Amadeus W.M.]

I have a binary file with data. Each block of 48 bytes is a record. I 
want to extract the first 8 bytes within each record. I'm thinking this 
should be possible with dd, but gawk, perl - anything goes. It just has 
to be fast, because the data files are ~ 1Gb.

I can do this in C++ but I was just wondering if it can be done with 
existing well tested tools.

Any suggestions? Thanks!