Retrospect Compression

[sjs01]

I'm using Retrospect 6.1, Mac OS 10.4.2 on a Mac 1.0GHz dual processor. When I backup/archive my audio files, which are Sound Designer ll format, Retrospect applies virtually no compression (usually about 1 or 2 %). When I stuff these SAME files using Aladin's Stuffit, they compress by 30-40%.

 

I've tried a multitude of things including: Archiving disk to disk (using different combinations of firewire and/or internal IDE drives) using software compression, Archiving disk to tape (Sony AITe200UL) using software compression, Archiving disk to tape (Sony AITe200UL) using hardware compression, all with the same results - virtually no compression.

 

Can anyone shed any light on why "Stuffit" will compress a set of Sound Designer ll files by 30-40%, but Retrospect will only compress these same files by 1-2%?

[Lennart_T]

How fast is Retrospect compressing the files vs StuffIt? I bet StuffIt is MUCH slower. If you had unlimited CPU time, the compression can be even larger.

 

 

 

You don't want to slow down your backups too much, do you?

[sjs01]

Actually, Stuffit is quite close in speed as I use it on pretty standard settings. I wouldn't expect either Retrospect, which is backup software, or the Sony AITe200UL, being a backup device, to compress the same as dedicated compression software.

 

But when products are advertised to perform a function, I do expect them to perform. Retrospect advertises that it can reduce the file(s) size up to half, while Sony advertises a compression ratio of 2.6. In the real world, I would have expected a savings of approx. 20% (given that stuffit will perform at 40%, and on smaller files I've achieved 83%).

 

So if anyone has any tips, or idea's on how to achieve even modest compreression ratio's with either the Retrospect software, or Sony AITe200UL, I would greatly appreciate your input.

 

Thanks

[Lennart_T]

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Actually, Stuffit is quite close in speed as I use it on pretty standard settings.

 

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That's not my experience, but YMMV.

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Retrospect advertises that it can reduce the file(s) size up to half, while Sony advertises a compression ratio of 2.6.

 

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In both cases it's "up to", depending on what you compress.

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So if anyone has any tips, or idea's on how to achieve even modest compreression ratio's with either the Retrospect software, or Sony AITe200UL, I would greatly appreciate your input.

 

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The kind of files that compresses easily are pure text files. The worst is already compressed files, such as MPG, JPG, ZIP, PDF etc. I have NO idea if sound designer's files are compressed or not, but at least they contain binary data which may be any way between pure text and already compressed files. Binary files are TIFF, AIFF, EXE, APP and a lot of other formats.

Also note that word processor documents (Word, Pages and AppleWorks docs) are binary, too.

[impala]

I'm not familiar with that file format.

Is Retrospect's built-in Compression Filter selector at work here?

just a thought...

[sjs01]

Thanks guys,

 

Sound Designer ll files are very similar to AIFF files, in that they do contain the same "amount" of binary data, and will compress virtually the same.

 

Using a compression specific software such as Stuffit, when compressing 2Gb of material, comprised of files ranging in size from 1mb up to 200Mb, you would expect to see a compression ratio ranging from 30% up to 80% per file (this is based on doing this for the past 14 years).

 

It's based on this information that I would expect / hope that current tape drives would also provide compression thats even half as good as dedicated compression software. Since it appears that this isn't the case, I'm currently in discusion with Sony as well. After all, by old Exabyte 8500, which is about 10 years old (and still works, but is slower then watching grass grow in the winter!), would compress these same files between 30 - 50%.

 

"Is Retrospect's built-in Compression Filter selector at work here?"

I've set the selector to "all files", and this didn't change anything.

 

I was hoping to hear from someone in the Audio Media industry, using AIT drives and Retrospect to hear about their experience?

 

Thanks one & all!