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Case
Registered: Aug 2002
Posts: 142 |
Depacking files from Memory
Hi, i am doing some coding and have hit a wall. I need to pack and then depack 3 pictures from memory depending on a keypress.
Can anyone help me with one ? |
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Krill
Registered: Apr 2002
Posts: 2980 |
What exactly is the question? :) |
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Beastifire
Account closed
Registered: Mar 2013
Posts: 40 |
Pack as in RLE (equal char) or crunch? |
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Oswald
Registered: Apr 2002
Posts: 5094 |
LZWVL
here. PC side packer, and sourcecode for depacker. RTFM I havent used it myself. |
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Dano
Registered: Jul 2004
Posts: 234 |
LZWVL works just fine, used it myself.
Another alternative is TinyCrunch which in the latest version works aswell, yet is a tad faster. |
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ChristopherJam
Registered: Aug 2004
Posts: 1409 |
Yes, TinyCrunch V1.2 should be fine for that, distribution even comes with test code that decrunches an image to $2000
NuCrunch V1.0.1 also has some sample code that decrunches an image, then an update to the image. It's a little slower, but it has a better compression ratio and lets you include multiple data segments in the stream, so the decruncher can then update a few different areas of ram for you with a single call. |
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Flavioweb
Registered: Nov 2011
Posts: 463 |
I guess you can use any packer you want.
Just get crunched bytes from ram instead from a mass storage device...
Also in exomizer docs there are some examples on how decrunch directly from ram. |
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Krill
Registered: Apr 2002
Posts: 2980 |
In general, try the fastest (but most likely least crunchy) packer/algorithm first, then move on to increasingly crunchier (and likely ever-so-slightly slower) packers, stop when you've found the first one to produce output that *just* fits in the memory reserved for it.
That way, repeating content can be displayed randomly or in rotation with a pleasantly quick turnover.
Over at http://codebase64.org/doku.php?id=base:compression_benchmarks is a rather recent graph.
Note the 4 clusters of algorithms and the overall "the slower the crunchier" and "the faster the less crunchy" trend*.
But keep in mind, your mileage may vary, depending on content.
Edit:
* Obviously not linear, might be something like a tweaked y=1/x (x*y=1) connection. Maybe "wasted_bytes = some_constant / num_cycles" or "num_cycles * wasted_bytes = some_constant". |
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Erol
Registered: Jul 2003
Posts: 6 |
I can only speak from my experience.
While making Rewind (Rewind) I have extensively tested Exomizer and ByteBoozer 2.
Everything in this demo is depacked from memory and you can see the amount of content that was managed to pack in under 202 blocks.
BB2 won because depacking was faster than Exomizer and it was important for the demo pace.
So it all depends on your preferences. You need to experiment a little. |
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Krill
Registered: Apr 2002
Posts: 2980 |
Yes, it very often pays off not to go for the best compression around at the cost of speed.
The only exception would be cracks which get bonus points for being the smallest version around, no matter if there's still space in memory/on the disk/image or not. :)
Exomizer being the reference for best general-purpose compression ratios on C-64, note that the graph I linked is timestamped at April 2017 at the time of writing this, which was before Exomizer 3. Exo 3 is quite a bit faster than Exo 2, yet still in the same slow camp. |
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Case
Registered: Aug 2002
Posts: 142 |
Hi, I should have been have given more information but it was late and i was tired.
Basically i have 3 standard bitmaps that i want to depack from memory and display one after each other on a loop.
Normally the way to do this would be to have one in each back and just flip between them, however i have some music sitting at $8000 which does not help.
I would also likt to do the depack from memory route so i can increase the number of images later on if needed.
I have tried to use ByteBoozer 2.0, but was unable to get it to depack (proberly due to my poor coding skills). If anyone has a working .exe of the packer and the depacker in kickass format i would be very grateful. |
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