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From Rob Weir <robw...@apache.org>
Subject Re: [DISCUSS] ODF file formats vs Zip
Date Mon, 10 Jun 2013 12:44:39 GMT
On Sun, Jun 9, 2013 at 4:01 PM, Dennis E. Hamilton
<dennis.hamilton@acm.org> wrote:
> Regina is correct about the only two compressions.  As far as I know, there is no way
to control which compression is used.  (If you save with Password, all files are always compressed.)
 Most of the time DEFLATE is used (although there are two files that are not usually compressed,
apparently to make metadata mining simpler for non-encrypted packages).
>
> There is currently no way to control the compression in AOO.  (The ODF specification
simply stipulates the compression that must be used when compression is done, not whether
compression is done for parts of unencrypted packages.)
>

Does anyone know whether AOO is smart enough to not waste time trying
to compress already compressed files, like PNG images?  This could
make a big difference in presentations.

-Rob


> I don't think it is the compression that is responsible for the slow-downs, it has to
do with other work that goes on in order to save a file.
>
> If you are careful about regularly saving manually while you are working, and you work
into a new copy so the starting version can't be damaged, you can disable auto-save to avoid
being interrupted in the midst of something you are doing.  There may be some glitches that
cause the time to increase in certain situations and those are caught from time to time. 
Using the latest version usually includes those improvements.  I suspect there are some other
performance issues around Save (and Auto-Save) that are more involved.
>
>  - Dennis
>
>
> -----Original Message-----
> From: Regina Henschel [mailto:rb.henschel@t-online.de]
> Sent: Sunday, June 9, 2013 11:41 AM
> To: users@openoffice.apache.org
> Subject: Re: [DISCUSS] ODF file formats vs Zip
>
> Hi Johnny,
>
> Johnny Rosenberg schrieb:
>> When working with big files, in my case spreadsheets, but possibly
>> other types of office files, saving the file will in some cases take a
>> lot of time. This is particularly annoying when auto-saving is
>> enabled. As I understand it, an ODF is a couple of files, most of them
>> XML files, brought together in a single file, then compressed to the
>> zip format.
>>
>> Does the ODF standard specify the compression ratio?
>
> There are two methods possible STORED and DEFLATED, see
> http://docs.oasis-open.org/office/v1.2/os/OpenDocument-v1.2-os-part3.html,
> section 2.2.
>
>   If not, it would
>> be convenient if the user could specify that. For example, if I prefer
>> saving to be as fast as possible, I could specify no compression at
>> all, just bring the files together in a tar-ball (if that's allowed)
>> or as an uncompressed zip.
>>
>> I don't know how much of the required time to save a file is used for
>> compression, but I imagine that there is room for speed enhancements
>> here.
>>
>> If this is not the way to go, maybe the extension could change as
>> well, indicating this is another file format, although conversion to
>> and from ODF should be very straight forward…
>
> Using another compression is still .zip file format.
>
> ODF has a flat file format without container too. This is implemented in
> LO but not in AOO. But in the flat format all pictures are stored in
> base64, because there is no folder to store them in original format.
>
>>
>> Thoughts about this?
>
> It would need tests to see, whether the method STORED is significant faster.
>
> Kind regards
> Regina
>
>
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