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List of issues#1805 Save or Save as may lost some data even without any change
Author: 
qy0u9me
qy0u9meDate created:
Type: question
Visibility: Everybody read only
Assigned to:
State: opened 
> What steps will reproduce the problem?
Some files are simply opened and then saved or saved as, and the new file is 500kb smaller
than the original file, without any changes.
> What is the expected output? What do you see instead?
Without any changes, the new file should be the same size as the original file.
> What version of the product are you using? Is it "nightly build"? Which operating system
do you have?
15.1.0 stable version, Windows 11 Dev 22572
> Please provide any additional information below. If the problem is related to a SWF
file, attach it here, otherwise we can't help you.
Here it is.
HandActionPlayer.swf (17,262 KiB)
The SWF file is compressed using ZLIB (Deflate).
When compressing SWF file, certain level of compression is used.
When the SWF is opened in FFDec, it is decompressed, but there is no way to get the level
of compression originally used, so when saving file later, we cannot anyhow imitate
original compression algorithm,
so it is compressed with default settings. This results in different file size.
There is no data loss here, just different compression used.
If you want no size change, then convert file to uncompressed - Edit header and set
compression to Uncompressed.
State: new→opened
Type: bug→question
Type: bug→question