Why filepack is not always the best option

Questions, bug reports, features requests, ... about the Oric Software Development Kit. Please indicate clearly in the title the related element (OSDK for generic questions, PictConv, FilePack, XA, Euphoric, etc...) to make it easy to locate messages.

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Twilighte
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Why filepack is not always the best option

Post by Twilighte »

If i filepack my complete game intending it to be loaded from tape then depacked, if there is one single byte wrong, the most likely scenario would be the decrunch would also fail and the loaded game would not work :(

However loading the full 48K game with errors will not neccesarily crash the game, especially if the corrupted bytes reside in the graphics or sound data which arguably take the largest amount of memory. It may just cause some anomolies ;)

There is the argument that says a packed game is smaller and therefore has less data to get wrong :P

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Xeron
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Post by Xeron »

Surely an ideal solution would be a packer with a small amount of redundancy so that some errors could be detected and repaired? It would be a bigger file, but probably could still be usefully smaller than the original.

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Chema
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Post by Chema »

Of course there are some techniques that could detect and repair individual errors, but it typically takes over 50% of additional space, IIRC. Hamming codes is an option.

I am not sure, however, that completely loading the game and then decrunching is the best way to go. Maybe a custom load routine which decompresses, detect and even correct bits on the fly could do a better job here (the sooner errors are detected, the better, and it would need less additional space). But maybe it is not possible on the Oric.

Nevertheless, and with the risk of getting a bit off topic, what surprises me (from my total ignorance about Oric load routines) is that nobody has come to a solution where loading errors are avoided to a good extent, and also some kind of "turbo" routines.

Is the hardware limiting this, or simply a domain nobody ever explored? I know there is a way of loading very quickly from CD, but it requires a very good signal (CD), while the turbo loading from other computers (speccy, for instance) worked with normal tapes.

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Twilighte
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Post by Twilighte »

Chema wrote:Is the hardware limiting this, or simply a domain nobody ever explored? I know there is a way of loading very quickly from CD, but it requires a very good signal (CD), while the turbo loading from other computers (speccy, for instance) worked with normal tapes.
Ok, since i don't want to move too far off the original topic i'll raise a new thread for my reply to this :{P

http://forum.defence-force.org/viewtopi ... =5265#5265

highwayman
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Post by highwayman »

i would prefer it to fail so i know it's corrupt.
much preferable to finding out much later.

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