EMULAB Forum

clrmamepro [English] => clrmame Discussion => Topic started by: falcon247 on 07 February 2013, 12:08

Title: 7Zip Compression Size Problem?
Post by: falcon247 on 07 February 2013, 12:08

Hi,  :)

 When I merged MAME 0.148 ROMs (.zip), using the rebuild option in ClrMamePro (.7z), everything went great and I have 8,720 .7z Files as it should be, but I noticed that the size is bigger than the set I found online (28.40 GB) and mine is (34.1 GB), so I opened one of the files (18wheelr) (77.7 MB):-

(http://img703.imageshack.us/img703/7536/18wheelr2.png)

 Then I extracted the files and Recompressed it using add to archive... (7-Zip) (65.4 MB):-

(http://img688.imageshack.us/img688/6443/18wheelr.png)

 I noticed that the method and block are different, so Why it's different? and What does it mean? Did I do anything wrong while rebuilding? and How I can fix this to get the highest compression rate?

PS:
 - I'm using 7-Zip 9.30 alpha (64-Bit) & ClrMamePro 4.09a (64-Bit)
 - 7z command Lines in ClrMamePro:
     Compress: a -y -r -ms=off -mx9 %1 %2
     Delete    : d -y -ms=off -mx9 %1 %2

 Any help would be appreciated.

Thanks

Title: Re: 7Zip Compression Size Problem?
Post by: Roman on 07 February 2013, 12:17

Different compression settings, different sizes....easy as that....
you can tweak more bytes of any file in an archive if you fiddle around with commandline switches of 7z....but again..who cares about gaining some free space in days where multi terabyte hds cost nearly nothing and a full MAME with CHDs is like 1/3 TB or something....

Tweaking here sounds a bit like finding a perfect AT connection string for modems...back in 198x....lots of work and testing to gain some transfer bits...

Title: Re: 7Zip Compression Size Problem?
Post by: Zandro on 07 February 2013, 17:17

The difference comes from specifying non-solid compression settings in cmpro (-ms=off). This is seriously recommended, as it keeps each file as a separately managed block within the archive, rather than merging everything together into a single block (see the column to the right of the one you highlighted) which entails a slower, memory intensive decomp/recomp process for each file.

Title: Re: 7Zip Compression Size Problem?
Post by: falcon247 on 07 February 2013, 17:50

Thanks Zandro for replying, but I didn't exactly understood what I suppose to do to fix this? I don't know that much about 7zip CommandLine. so can you please tell me what I should do exactly?

thanks

Title: Re: 7Zip Compression Size Problem?
Post by: Zandro on 08 February 2013, 01:11

If you want to 'fix' the 'issue' of it not compressing as much, set -ms=on and rebuild.  Again, this is ill advice.  You shouldn't want the extra overhead.

Other reading: http://romshepherd.com/smf/index.php/topic,677.msg2958.html#msg2958 (http://romshepherd.com/smf/index.php/topic,677.msg2958.html#msg2958)

Title: Re: 7Zip Compression Size Problem?
Post by: falcon247 on 08 February 2013, 09:20

 I know it's better to use .zip over .7z and that Multi-Terabytes HDs is cheap, but this is driving me crazy, I'm trying to fix this for days but nothing is working, I set -ms on but still it won't use solid-compression, Is this a bug in ClrMamePro or in 7-Zip 9.30 alpha? I just want to know why ClrMamePro won't use solid-compression even though I set it on? I've become obsessed with this!!!  ;D

New 7z command Lines in ClrMamePro:
     Compress: a -y -r -ms=on -mx9 %1 %2
     Delete    : d -y -ms=on -mx9 %1 %2

 Any help would be appreciated

Thanks

Title: Re: 7Zip Compression Size Problem?
Post by: Roman on 08 February 2013, 11:58

you wont be able to do further fixing on solid archives. they are not recommended to be used. as mentioned before it's not worth the hassle anyway.