vision20-20

Hi guys, I am completely clueless when it comes to DVR's and would like some assistance. I would like to know if there are any DVR's on the market that can back data up on to a flash drive in MPEG 4 format. Most of the DVR's I have looked at have the AVI format option when backing up but a client of mine is interested in having the back up format as MPEG-4. The DVR is going to be used to capture diving operations through AHD cameras so a AHD compatible DVR is preferable. I thank you in advance.