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• About AllDup
• Product Description
• System Requirements
• Important Notes

• AllDup Main Window
• Main Window
• Source Folder
• Search Methods
• Search Options
• Archive Files
• Database
• File Filter
• Folder Filter
• Windows Environment Variables
• File Preview
• Profiles
• Saved Search Results
• Options
• Update Tool

• Search Result
• Search Result
• Menu Bar / Toolbar
• Context Menus
• File Manager
• Keyboard Shortcuts

• Miscellaneous
• Command Line
• Text Placeholders
• Date and Time Placeholders
• Speed Comparison Byte-by-Byte vs. SHA-1

File Content

With this file property files with the same or similar content can be found.

Comparison Methods

For content comparison, the following methods are available:

• Byte-by-Byte
• Checksum MD5 (128-bit)
• Checksum SHA-1 (160-bit)
• Checksum SHA-2 (256-bit)
• Checksum SHA-2 (384-bit)
• Checksum SHA-2 (512-bit)

Byte-by-Byte

With this comparison method, the content of the files to be compared is read piece by piece and compared with each other. If a match of 100% is set, the file comparison is aborted as soon as a difference is detected. If a match of less than 100% is set, the complete file content is always compared in order to calculate the percentage match.
Example: If a match of 90% is set, all files are classified as duplicates that have a match of at least 90%.

Checksums

With this comparison method, the file is always read completely and a checksum of its content is created, which is then used for further file comparisons. Comparing checksums can be faster for many files with the same file size than comparing the complete content of the files again each time. See Speed Comparison.

Options

• Ignore ID3 tags of MP3 files
  With this option, the following tags are ignored during a content comparison of MP3 files:
  • ID3v1
  • ID3v2
  • Lyrics3 v2
  • APE v2
  AllDup ignores duplicate ID3v2 tags at the beginning of an MP3 file and duplicate ID3v1 tags at the end of the file.
• Ignore metadata of JPEG/CR2 files
  With this option, the metadata in image files with the extensions JPEG, JPG and CR2 is ignored and only the compressed image data is compared.
• Ignore metadata of FLAC files
  With this option, the metadata in FLAC files is ignored during a content comparison.
• First compare a data block at the end of both files
  With this option, during a content comparison, a data block at the end of both files is compared first. This can potentially significantly reduce the time required for content comparison.
• Block size of the read buffer
  With this option, you can set the block size for comparing the content of two files. This option allows you to quickly detect different content at the beginning of a file without first having to read a large part of both files. At the start of the comparison, a data block with the size of the defined start value is read from both files. The comparison is stopped if the two blocks are not identical. Otherwise, the block size is increased by the defined step size and another comparison is performed. The increase of the block size is performed up to the defined maximum value. After that, a block size with the maximum value is always read.