Re: [Flashcoders] Simple compression algo?
Hi Juan - I don't think it's assigning the string that's slow. It's calling sendAndLoad that is slow, because I think when you make the call the data is urlencoded or something. I've already found that, and am not calling it. I was simply outputting the before and after string lengths to see how Base64 and LZW worked. Could be the class I was using, but either way it was way too slow to be useful to me. My simple array compressor is nearly instant and on some images it's getting me an 80%+ reduction in the array size, which is more than enough for my needs. On average it's only around a 20% or so reduction, but that's still good enough as my images are not very big. I think you're idea is great, and for AS3 a definite, but in AS2 I fear it's just going to be too slow. Plus, I've already spent far too long on this little aside and should be moving on, though I do enjoy these kinds of things. If you want to see some of my test results, I posted a little article on my blog: www.dmennenoh.blogspot.com Thanks much! Dave - Head Developer http://www.blurredistinction.com Adobe Community Expert http://www.adobe.com/communities/experts/ ___ Flashcoders mailing list Flashcoders@chattyfig.figleaf.com http://chattyfig.figleaf.com/mailman/listinfo/flashcoders
Re: [Flashcoders] Simple compression algo?
I don't think it's assigning the string that's slow. It's calling
sendAndLoad that is slow, because I think when you make the call the data is
urlencoded or something
Yes, you're probably right. I thought maybe the string was encoded as soon
as it assigned, but it makes more sense that the encoding is done when the
data is actually sent.
If you're code already works, great, go with it. I was just suggesting
another approach, but I understand what you mean. You've invested
a considerable time on it and already works pretty good for your actual
needs, so it makes no sense to try another method that could be worse
performance-wise.
I've taken a glimpse at your code, by the way. I like that it's simple and
neat, but I was thinking that maybe you could avoid the first loop, by just
adding an else to the main if in the second loop. Not sure if it'll make a
noticeable difference in performance, since assigning an empty string to an
array element is fast, but you'll be saving almost 100.000 iterations (on a
320 x 300 image).
Something like this:
comp[0] = orig[0];
var lastEqualIndex = 0;
for(var i = 1; i l; i++){
if(orig[i] != comp[lastEqualIndex]){
//new color
comp[i] = orig[i];
lastEqualIndex = i;
} else {
comp[i] = ;
}
}
return comp;
}
All in all, it's a good and simple solution!
Cheers
Juan Pablo Califano
2008/2/5, Dave Mennenoh [EMAIL PROTECTED]:
Hi Juan - I don't think it's assigning the string that's slow. It's
calling
sendAndLoad that is slow, because I think when you make the call the data
is
urlencoded or something. I've already found that, and am not calling it. I
was simply outputting the before and after string lengths to see how
Base64
and LZW worked. Could be the class I was using, but either way it was way
too slow to be useful to me. My simple array compressor is nearly instant
and on some images it's getting me an 80%+ reduction in the array size,
which is more than enough for my needs. On average it's only around a 20%
or
so reduction, but that's still good enough as my images are not very big.
I think you're idea is great, and for AS3 a definite, but in AS2 I fear
it's
just going to be too slow. Plus, I've already spent far too long on this
little aside and should be moving on, though I do enjoy these kinds of
things. If you want to see some of my test results, I posted a little
article on my blog: www.dmennenoh.blogspot.com
Thanks much!
Dave -
Head Developer
http://www.blurredistinction.com
Adobe Community Expert
http://www.adobe.com/communities/experts/
___
Flashcoders mailing list
Flashcoders@chattyfig.figleaf.com
http://chattyfig.figleaf.com/mailman/listinfo/flashcoders
___
Flashcoders mailing list
Flashcoders@chattyfig.figleaf.com
http://chattyfig.figleaf.com/mailman/listinfo/flashcoders
Re: [Flashcoders] Simple compression algo?
Sounds a bit like Run Length Encoding Right, I mentioned that. :) I kept it simple to be able to reconstruct the image from it more easily in PHP. Gotta try the base64 thing next. Dave - Head Developer http://www.blurredistinction.com Adobe Community Expert http://www.adobe.com/communities/experts/ ___ Flashcoders mailing list Flashcoders@chattyfig.figleaf.com http://chattyfig.figleaf.com/mailman/listinfo/flashcoders
Re: [Flashcoders] Simple compression algo?
Actually, from my tests (on the component I made, which was AS 3.0), the bottle neck was not encoding to base 64 per se (as I assumed at first), but assigning the resulting string to the LoadVars object (o URLRequest in my case...). If I commented out that specific line, it worked way faster; when the big string was assigned to the URLRequest, it took a while, even in AS 3.0 (I'm talking about really big images, perhaps some 1 MB string...) In my component I used a mix of AS 2.0 and AS 3.0. The app was AS 2.0; I got the raw pixel data and sent it to the AS 3.0 module (loaded in an invisible frame) through a local connection (in various passes not just the whole array because there's a limit, I think it's 40 Kb or something like that). Once I got the raw pixel data in the AS 3.0 module I converted it to jpeg, then encoded it to Base64, and the post it to the server. It took a while to get it right, but finally I got it working. Later I realized that the URLRequest object lets you send binary data, so I avoided the base64 encoding step. You're stuck with AS 2.0, so there are things you can't do. For instance, posting binary data to the server. As far as I know, you just can send text, using a LoadVars obj. However, you can try to create the jpeg in the swf. I'm not saying it'll be faster. Who knows. But maybe it's worth trying. I have a JPGEnconder class, that can be ported to AS 2.0. The code is far from understandable to me, but just adapting it to AS 2.0 seems feasible. The only thing missing is the native ByteArray class, but it's not that hard to make one (in the end, it's just a storage structure with a pointer / cursor and a few methods to make it easier reading bytes, shorts, ints, etc). So, I think the parts needed to give it a try are there. If you're interested I can post somewhere the Base64 class (AS 3.0, should be ported), the ByteArray (might need to add some methods but already reads/writes unsigned bytes and unsigned shorts), and a Base64 encoder (AS 2.0, too, I've used to some extent and works fine). What I was thinking, to sum things up, is this: * get the raw image data into a ByteArray * encode that data to create a JPEG image in memory * encode that image data to base64 * post the resulting string to the server Might or might not cut it, haven't tried it as I said, and that's really the only way to know. If you want to use some of the code I mentioned to give it a try, just let me know. Cheers Juan Pablo Califano 2008/2/4, Dave Mennenoh [EMAIL PROTECTED]: you're sending a comma separated string to the server? why not have 2 hey digits for all the data and omit the comma? this would bring your data to 2/3 of its size, which means 26sec*2/3 = 17.3sec when this works, you could try to send binary data - so instead if sending the string ff you would send the binary byte 255. if this works, this would cut the time in half again = 8.6sec if you can't create binary data, you could still use base64 encoding instead, which would give you 8.6*1.33 = 11.5sec. Yeah, I'm sending an array of colors. What's a hey digit? And it's not FF, that was just an example, it's colors so it's FF or 16777215 as an integer and it's not any faster to send as integers, in fact I found it a little slower so am sending the hex string. Keeping in the commas just makes it easy to reconstruct the image since if an array index is null I just use the last good color. I did say it was simple. :) I'll definitely give base64 a shot. I'm stuck with AS2 here so I didn't think I could do binary, but Juan seems to say it's possible. Thanks Dave - Head Developer http://www.blurredistinction.com Adobe Community Expert http://www.adobe.com/communities/experts/ ___ Flashcoders mailing list Flashcoders@chattyfig.figleaf.com http://chattyfig.figleaf.com/mailman/listinfo/flashcoders ___ Flashcoders mailing list Flashcoders@chattyfig.figleaf.com http://chattyfig.figleaf.com/mailman/listinfo/flashcoders
[Flashcoders] Simple compression algo?
Hi all, I've been working on allowing users to dowload a jpeg from a movieClip in AS2 and came up with a simple, yet novel compression idea, that's a bit like RLE but not quite. Basically it is this - analyze the image pixel by pixel to get the hex color codes into an array. Then, make a new array the same length as the colors array, but filled with - so it's full of nulls. I then iterate the colors array and if the current color is the same as the previous color, I don't add it to the new array - otherwise I do. So if I have: [ff, ff, ff, aa, ff, aa, aa, aa, aa] the new array would be [ff, , , aa, ff, aa, , , ] It makes it easy to reconstruct too, and it's taken about 7 seconds off in my tests. Saving a 300x320 image went from about 26sec to now 19sec. It's not huge, but everything is something... Dave - Head Developer http://www.blurredistinction.com Adobe Community Expert http://www.adobe.com/communities/experts/ ___ Flashcoders mailing list Flashcoders@chattyfig.figleaf.com http://chattyfig.figleaf.com/mailman/listinfo/flashcoders
Re: [Flashcoders] Simple compression algo?
Interesting stuff. I assume you're creating the jpeg on the server since you seem to be passing the raw bitmap data (compressing the pixel data with your algorythm). Perhaps another approach worth trying is creating the jpef directly on the Flash app. Have you tried it? I've done that with AS 3.0, using a class provided by adobe, JPGEncoder, that I found browsing the web. I think it could be easily ported to AS 2.0; the only AS 3.0 feature used in the encoder is the ByteArray, which can be ported to AS 2.0 as well. I've already done that and it works fine; of course, since it's AS and not native code (and since it runs in the AVM1 instead of the AVM2), the performance would not be as good as the native ByteArray. I haven't benchmarked or stress-test it, but so far, it gets the job done. The cons of this approach: it will require more processing on the client side (perhaps too much to consider using it in production, but the only way to know is testing and benchmarking, I guess). On the other hand, sending a ~10 - ~15 Kb jpeg upstream should be way faster than posting a ~750 KB string (assuming 24 bits per pixel, 300 px * 320 px * 4 bytes (3 per pixel, 1 for the each comma) * 2 (taking the max value of 'ff', 2 chars). Probably it's a bit less than that since your are compressing it... Can you describe the flow of your app? Cheers Juan Pablo Califano - Original Message - From: Dave Mennenoh [EMAIL PROTECTED] To: Flash Coders List flashcoders@chattyfig.figleaf.com Sent: Sunday, February 03, 2008 8:12 PM Subject: [Flashcoders] Simple compression algo? Hi all, I've been working on allowing users to dowload a jpeg from a movieClip in AS2 and came up with a simple, yet novel compression idea, that's a bit like RLE but not quite. Basically it is this - analyze the image pixel by pixel to get the hex color codes into an array. Then, make a new array the same length as the colors array, but filled with - so it's full of nulls. I then iterate the colors array and if the current color is the same as the previous color, I don't add it to the new array - otherwise I do. So if I have: [ff, ff, ff, aa, ff, aa, aa, aa, aa] the new array would be [ff, , , aa, ff, aa, , , ] It makes it easy to reconstruct too, and it's taken about 7 seconds off in my tests. Saving a 300x320 image went from about 26sec to now 19sec. It's not huge, but everything is something... Dave - Head Developer http://www.blurredistinction.com Adobe Community Expert http://www.adobe.com/communities/experts/ ___ Flashcoders mailing list Flashcoders@chattyfig.figleaf.com http://chattyfig.figleaf.com/mailman/listinfo/flashcoders ___ Flashcoders mailing list Flashcoders@chattyfig.figleaf.com http://chattyfig.figleaf.com/mailman/listinfo/flashcoders
Re: [Flashcoders] Simple compression algo?
Sounds a bit like Run Length Encoding Dave Mennenoh wrote: Hi all, I've been working on allowing users to dowload a jpeg from a movieClip in AS2 and came up with a simple, yet novel compression idea, that's a bit like RLE but not quite. Basically it is this - analyze the image pixel by pixel to get the hex color codes into an array. Then, make a new array the same length as the colors array, but filled with - so it's full of nulls. I then iterate the colors array and if the current color is the same as the previous color, I don't add it to the new array - otherwise I do. So if I have: [ff, ff, ff, aa, ff, aa, aa, aa, aa] the new array would be [ff, , , aa, ff, aa, , , ] It makes it easy to reconstruct too, and it's taken about 7 seconds off in my tests. Saving a 300x320 image went from about 26sec to now 19sec. It's not huge, but everything is something... Dave - Head Developer http://www.blurredistinction.com Adobe Community Expert http://www.adobe.com/communities/experts/ ___ Flashcoders mailing list Flashcoders@chattyfig.figleaf.com http://chattyfig.figleaf.com/mailman/listinfo/flashcoders -- Glen Pike 01736 759321 www.glenpike.co.uk http://www.glenpike.co.uk ___ Flashcoders mailing list Flashcoders@chattyfig.figleaf.com http://chattyfig.figleaf.com/mailman/listinfo/flashcoders
RE: [Flashcoders] Simple compression algo?
Hi, Hi all, I've been working on allowing users to dowload a jpeg from a movieClip in AS2 and came up with a simple, yet novel compression idea, that's a bit like RLE but not quite. Basically it is this - analyze the image pixel by pixel to get the hex color codes into an array. Then, make a new array the same length as the colors array, but filled with - so it's full of nulls. I then iterate the colors array and if the current color is the same as the previous color, I don't add it to the new array - otherwise I do. So if I have: [ff, ff, ff, aa, ff, aa, aa, aa, aa] the new array would be [ff, , , aa, ff, aa, , , ] you're sending a comma separated string to the server? why not have 2 hey digits for all the data and omit the comma? this would bring your data to 2/3 of its size, which means 26sec*2/3 = 17.3sec when this works, you could try to send binary data - so instead if sending the string ff you would send the binary byte 255. if this works, this would cut the time in half again = 8.6sec if you can't create binary data, you could still use base64 encoding instead, which would give you 8.6*1.33 = 11.5sec. regards Claudius ___ Flashcoders mailing list Flashcoders@chattyfig.figleaf.com http://chattyfig.figleaf.com/mailman/listinfo/flashcoders
