Can Repeatedly Zipping and Unzipping Files Reduce Their Quality?
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MellowPine47
If I compress files with WinRAR and then extract them repeatedly, can the files gradually become damaged or lose quality? I'm especially wondering whether this is different for documents, images, videos, or other file types. I also want to use password protection on the archive.
Answers
Lossless compression works by storing the same data more efficiently, not by throwing information away. That’s different from formats such as JPEG, MP3, or heavily compressed video, where some data is discarded during re-encoding and quality can decrease.
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No. ZIP and RAR compression are lossless, so extracting the archive restores the exact same bytes every time. The files don’t gradually lose quality, regardless of how often you compress and extract them.
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There is a small practical risk that an archive or storage device could become corrupted, but that risk isn’t caused by repeatedly compressing the files. Use archive integrity checks and keep backups if the files are important. Password protection is also fine and doesn’t make the compression lossy.
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