Can Repeatedly Zipping and Unzipping Files Reduce Their Quality?
Asked by
MellowPine47
If I compress files with WinRAR or ZIP and then extract them repeatedly, can the files gradually become damaged or lose quality? I'm especially wondering whether this works differently for documents, images, music, or videos. I also want to use password protection for the archive.
Answers
Lossless compression simply stores the same data more efficiently. When you extract the archive, every bit is restored, so documents, images, audio, and video files do not degrade just because they were archived multiple times.
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There is always some practical risk of an archive or storage device becoming corrupted, but that risk is not caused by repeatedly compressing the file. Keep a backup, and consider using the archive’s password-encryption option if you need protection.
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No. ZIP and RAR normally use lossless compression, which means the extracted file is identical to the original. Repeating the compress-and-extract process does not gradually reduce its quality.
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This is different from repeatedly re-encoding a JPEG, MP3, or video with a lossy format. Those formats discard information, while normal ZIP or RAR archiving does not.
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MellowPine47: That makes sense. I mainly wanted the password protection, so using an encrypted archive should be fine as long as I keep a backup.