Basic compression speed?

Try using DeflatorOutputStream, everything you write to it is compressed automatically. InflatorInputStream does the reverse.

Write to

import java.io.ByteArrayOutputStream;

import java.io.File;

import java.io.FileInputStream;

import java.io.IOException;

import java.util.zip.DeflaterOutputStream;

public class CompressTest {

public static void main(String args[]) throws IOException {

String str = readFile(args[0]);

compressText(str);

}

public static String readFile(String fileName) throws IOException {

File file = new File(fileName);

byte[] bytes = new byte[(int) file.length()];

FileInputStream fis = new FileInputStream(file);

fis.read(bytes);

fis.close();

return new String(bytes, 0);

}

public static void compressText(String text) {

try {

byte[] stringBytes = text.getBytes();

long start = System.currentTimeMillis();

ByteArrayOutputStream baos = new ByteArrayOutputStream();

DeflaterOutputStream dos = new DeflaterOutputStream(baos);

dos.write(stringBytes);

dos.close();

byte[] bytes = baos.toByteArray();

long end = System.currentTimeMillis();

double compressionRatio = (double) text.length() / bytes.length;

double runTime = (end - start) / 1000.0;

System.out.println("Compression ratio=" + compressionRatio + ", compression time=" + runTime + " secs");

} catch (IOException e) {

e.printStackTrace();

}

}

}

I ran this for the king james version of the bible. A big text file from ftp://unboundftp.biola.edu/pub/kjv.zip and got the following results for the text file.

Compression ratio=3.2839847108115876, compression time=1.047 secs

That is about 1 second to compress a 5 MB of text (on a 1.8 GHz AMD)

Peter-Lawreya at 2007-7-8 1:06:39 >

My arithmetic compressor did around 30kB/s - 300kB/s IIRC

It was on computer underclocked to 1.8 GHz

I consider compressing 700MB avi under an hour as very nice for an arithmetic compressor, so... You have the answer.

Static "huffman" tree is faster, but not as much interesting.

Raghar

Lord_of_the_chaosa at 2007-7-8 1:06:39 >