Since I couldn't find what I was looking for, I wrote my own (sort of **). This prompted me to search for a program that would generate file CRCs for all files in a directory. Not only that a checksum is not guaranteed to catch multiple errors. Whilst HJsplit allows you to generate a checksum for each file, it is very tedious to do 60 as in the case of my 60MB stack. The answer here is to generate a Checksum or CRC for each of the chunks and have the recipient compare his with yours. The trouble is, how do you determine which chunk is bad? There isn't a lot of use going to all the trouble of zipping/splitting/joining if the final result at the other end is still an unusable file!. How do you know that one of the chunks wasn't corrupted? You could (and probably should) ZIP the file before splitting - even a SEGY file will compress a little bit, and the ZIP procedure adds a CRC to the file so that when the rejoined file is Unzipped, if there is a corrupted chunk, then the recipient will know. Splitting the file though is not the end of the story. Lors de la division dun fichier, vous pouvez spécifier la taille des parties. Le programme Freebyte est doté de quatre fonctions faciles à utiliser : Séparer, joindre, comparer et vérifier. I usually split big files into 1MB (1000KB) chunks for uploading. FreeByte (Gratuit) HJSplit est un outil gratuit permettant de diviser et de recombiner des fichiers dune taille pouvant atteindre plus de 100 gigaoctets. It's very easy to use, and handles both splitting and joining, so your recipient should have it also. There is an excellent piece of freeware available that does all this, it's called HJSplit and is available for download from here :

Whoever downloads these chunks has to be able to join them all up of course. My solution was to split the file into small chunks and send the chunks as separate files. It is usually impossible to upload a file of this size to even an FTP site as the link just drops out. And of course being shared with everyone on crew meant even less was available to me for my big upload. 64KbS is little better than a dial up modem. Recently I was in a situation of having to upload a 60MB field stack to an FTP site over a crew's shared 64KbS VSAT link. The problem is that whilst the Oil Company (or Contractor) demand these files, they are seldom prepared to provide a decent VSAT link to allow it. They could be Field Stacks, Raw Field Records, Photographs, Reports or any number of other files. Often on field crews these days it is necessary to send large files of various sorts.

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