7-Zip better than PA 2011?

[ampillion]

Hi, I just conducted a benchmark comparison test pitting 7-Zip 9.20 vs PA 2011 and I have noticed that archives created by 7-Zip are relatively small compared to the same archives created by PA 2011 with the same settings for both of them.

I used VLC Media Player (81.2 MB) as a test sample and here are the settings shown in the screenshots:

And here are the results:

7-Zip – 16.6 MB
PA 2011 – 17.4 MB

Although the difference between the output file size is minor, it becomes more apparent when compressing 1 GB or more.

Could the lack of advanced options (Dictionary and Word size) in PA 2011 played a role in this discrepancy? And is there a way to get PA 2011 to match the output file size of its 7-Zip counterpart?

[spwolf]

we both use different settings but overall difference should be literally in bytes or kb’s at max.

thanks for the report, we will be checking it out

[spwolf]

there is possibility of 7z using some extra settings in later versions for stronger compression in ultra mode… max and others are the same… we will be checking it out.

[ampillion]

@spwolf:

we both use different settings but overall difference should be literally in bytes or kb’s at max.

thanks for the report, we will be checking it out

Well, there is another thing you might want to check into. I ran a benchmark test again, this time with five duplicates of a previously mentioned test sample totaling 406 MB (5 x 81.2 MB) and I changed the compression level from Ultra to Normal for both archivers. Note that when I set it to normal in 7-Zip, the dictionary and word size were automatically changed to 16 MB and 32, respectively. Here are the results.

7-Zip – 26.0 MB (00:01:23)
PA 2011 – 26.0 MB (00:01:59)

Both of the output file size are the same despite the miniscule differences in bytes (see screenshots above). However, the time it took to compress them are strikingly obvious: 7-Zip was 36 seconds faster than PA 2011. Heck, I even changed the dictionary and word size back to the original (the default settings for Ultra) with the normal settings intact and it was still 7 seconds faster and resulted in slightly better compression ratios, 24.7 MB to be accurate.

All things said, I’m not sure why you used a different settings than the one used in 7-Zip, but I feel your choice of settings is in need of some kind of adjustment since it’s not quite up to par with 7-Zip’s settings.

I’m only bringing this up so you can improve the 7-Zip engine.

[spwolf]

@ampillion:

Well, there is another thing you might want to check into. I ran a benchmark test again, this time with five duplicates of a previously mentioned test sample totaling 406 MB (5 x 81.2 MB) and I changed the compression level from Ultra to Normal for both archivers. Note that when I set it to normal in 7-Zip, the dictionary and word size were automatically changed to 16 MB and 32, respectively. Here are the results.

7-Zip – 26.0 MB (00:01:23)
PA 2011 – 26.0 MB (00:01:59)

Both of the output file size are the same despite the miniscule differences in bytes (see screenshots above). However, the time it took to compress them are strikingly obvious: 7-Zip was 36 seconds faster than PA 2011. Heck, I even changed the dictionary and word size back to the original (the default settings for Ultra) with the normal settings intact and it was still 7 seconds faster and resulted in slightly better compression ratios, 24.7 MB to be accurate.

All things said, I’m not sure why you used a different settings than the one used in 7-Zip, but I feel your choice of settings is in need of some kind of adjustment since it’s not quite up to par with 7-Zip’s settings.

I’m only bringing this up so you can improve the 7-Zip engine.

try with lzma and see what happens there.

[davidsplash]

one idea realted to this isto note that the 7zip engine is newer than the one in pa

Did you use the beta 7zip version by the way?

[RJWaring]

@davidsplash:

one idea realted to this isto note that the 7zip engine is newer than the one in pa

Did you use the beta 7zip version by the way?

I must admit i love the 7zip format it is my preferred compression technique.

But i dont use their application as i prefer PowerArchiver. Is the Beta 7zip any good? better compression by much? when can PA Adapt it?

[davidsplash]

the only option possible is to have 7zip as a plugin sing the 7zip engine so that when a beta version of 7zip comes out you can choose to use that engine to ensure the best possible and uptodate 7zip experience

[spwolf]

@Sir:

I must admit i love the 7zip format it is my preferred compression technique.

But i dont use their application as i prefer PowerArchiver. Is the Beta 7zip any good? better compression by much? when can PA Adapt it?

compression should be exactly the same (or within 1%)… if it isnt, then it is an bug :-)

[ampillion]

@spwolf:

try with lzma and see what happens there.

Like lzma2, I got the same results with lzma under normal setting. The same is true for PA 2011 except the compression time was quite different.

7-Zip – 26.0 MB (00:01:23)
PA 2011 – 26.0 MB (00:01:29)

Both archivers yielded the same size for both files, but PA 2011 took less time to compress it (30 seconds faster) though it trails 7 seconds behind 7-Zip. It seems to me that PA 2011 handles lzma better than lzma2 which should not be the case considering that there’s no real difference between lzma and lzma2 in terms of compression ratio, compression/decompression speed, or RAM usage. The only big difference in lzma2 is when taking advantage of the extra CPU threads. In fact, I just realized that PA 2011 with lzma2 enabled do not even utilize the full extent of my Core i7-860 processor. 7-Zip, on other hand, has no problems maxing out my quad-core setup (8 CPU threads) which finish in 36 seconds albeit at the expense of few extra MBs.

@davidsplash:

one idea realted to this isto note that the 7zip engine is newer than the one in pa

Did you use the beta 7zip version by the way?

No, I’m using the latest stable version (9.20) and unless stated otherwise, I assume PA 2011 is using this version as well.

[ampillion]

It’s worth mentioning that the ZIPX format does make full use of my quad-core setup, thanks to “Multicore compression” option. I wondered why this option doesn’t exist for 7z format?

[spwolf]

@ampillion:

It’s worth mentioning that the ZIPX format does make full use of my quad-core setup, thanks to “Multicore compression” option. I wondered why this option doesn’t exist for 7z format?

it is due to the different engines - our engine for zip/zipx is our own and multicore optimized. For LZMA/LZMA2 we use 7zip engine.

What is happening right now with your issues is:
a. We didnt optimize Ultra settings in same way as 7zip - this should be simple fix in next release.
b. Devs turned off multicore in lzma2 since it would crash PA due to some issue with 7zip dll. We need to figure this one out.

thanks for all the help.