That sounds good. Something like the JPEG VLC for the actual distance between entries and just store deltas on a space filling curve should be good then.


On 14 January 2014 13:11, Oscar Forth <oscar@trueharmoniccolours.co.uk> wrote:
Just a random though, so apologies if i'm talking about my arse, but ... couldn't you just use something like the bit plane compression from Wavelet Difference Reduction (WDR)?

A lot depends on your data, I appreciate, so this may not work out as any significant saving ...

I wrote about the compression method in my blog a few years back:

http://trueharmoniccolours.co.uk/Blog/?p=55

Obviously thats in the context of a full wavelet image compressor so you will have to just grab the part I explain in the link above.

Also apologies for the code formatting on my blog ... ill fix it one day ;)

Oscar

On 14 January 2014 12:37, Richard Fabian <raspo1@gmail.com> wrote:
The web is full of different solutions for compressing things, but some of you have probably already done this and found a really good ratio compression scheme that fits what I'm asking about.

I've got a load of entites, (4-7k) that live on a grid (1024x1024), and I need to persist them to a savegame which gets sent across the network to keep the save safe. I need to compress it. I'm compressing the entities in the world already, ones that have been affected cost a few bytes, but the but for the ones that don't have any changes, all I'm left with is the coords. There are only a few that need the fatter compression, but at the numbers I'm looking at, those "unchanged entity" coords add up to a lot of data when storing as 20 bit structs. This is too much for sending over the network regularly as part of a save.

I've had some ideas on how to compress the data, but they might be crap. I don't know.

I can't easily regenerate the set so thought someone who wanted to compress consumables might know the name of a good solution for sparse bitset compression. The bits are clumped around different areas of the grid, so I feel that something that leverages spatial coherence might do well.

Any leads would be highly appreciated.

--
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