DeflOpt can further compress Zopfli output

[GoogleCodeExporter]

What steps will reproduce the problem?
1. compress with Zopfli
2. run DeflOpt on its output... it's sometimes further compressed


What is the expected output?
Zopfli is supposed to produce the smallest Deflate stream

What do you see instead?
It's not the case since DeflOpt can still reduce Zopfli output

What version of the product are you using?
Current source

On what operating system?
Linux

On enwik8:

***                 DeflOpt V2.07                 ***
***       Built on Wed Sep  5 18:56:30 2007       ***
***  Copyright (C) 2003-2007 by Ben Jos Walbeehm  ***

"Z:/home/caveman/zopfli/enwik8.gz"
Number of bytes saved: 1,745 (34,995,756 --> 34,994,011) (13,960 bits)
File rewritten.

Number of files processed  :        1
Number of files rewritten  :        1
Total number of bytes saved:    1,745


DeflOpt is avaible here:
http://www.walbeehm.com/download/
It can be run on Linux using Wine.

Defluff is a similar tool:
http://encode.ru/threads/1214-defluff-a-deflate-huffman-optimizer

If you need a tool to compare Deflate streams, defdb can be downloaded from 
here:
http://encode.ru/threads/1428-defdb-a-tool-to-dump-the-deflate-stream-from-gz-an
d-png-files

Original issue reported on code.google.com by cryo...@free.fr on 1 Mar 2013 at 5:04

[GoogleCodeExporter]

Thanks for the report. Anything that makes the output smaller is good. We're 
considering to add improved tree encoding to Zopfli.

Original comment by lode.van...@gmail.com on 10 Apr 2013 at 4:05

[GoogleCodeExporter]

Is this feature still planned for inclusion into zopfli?

Original comment by np.m...@gmail.com on 10 Dec 2013 at 9:18

[GoogleCodeExporter]

I would like to see this feature added.  I am avoiding using zopfli for 
anything because I don't want to implant it now and then a second time when 
this feature is added.

Original comment by per...@gmail.com on 10 Dec 2013 at 4:48

[GoogleCodeExporter]

my test result with the latest revision b87006baae7d:
Original               3,779,490 bytes
old Zopfli             3,597,554 bytes
old Zopfli + DeflOpt   3,586,025 bytes
new Zopfli             3,579,219 bytes
new Zopfli + DeflOpt   3,577,427 bytes

Original comment by jayxon on 24 Jul 2014 at 6:40