How can I delete data from in a hexdump file from one offset to another?

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http://unix.stackexchange.com – I've created a disk image which was zeroed, formatted to ext4 file system, and then had several various files copied to it. I'm trying to extract these files using a combination of xxd and dd, but with certain files I find their size has increased and cannot be properly interpreted by their default viewer/player. The reason behind this is because the file system is inserting several almost identical chunks of what I guess is some form of metadata periodically on the image. The data starts off as, or pretty similar to the hex code below, followed by what seems to be a random assortment of cha (HowTos)