Search Method 'File Content'

This search method enables you to compare the content of files with the same file size.

Comparison Method

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

This comparison method reads the content of both files chunk by chunk and compares the chunks byte by byte. With a specified percentage match of 100% the comparison of the two files will be stopped if the chunks are not identical. With a percentage match below 100% the complete content of both files will be analyzed to calculate the percentage match between them.
Example: With a specified percentage match of 90% all files with a percentage match of 90% or higher will be classified as duplicates.

Checksum

The checksum method reads the complete file content and creates a checksum of the content for further comparisons. Using a checksum could be much faster than a byte-by-byte comparison when you compare a lot of files. Comparing only the stored checksum will avoid to read the complete content of these files again and again. See Speed Comparison Test.

Ignore ID3 Tags of MP3 files

This option enables you to ignore the following tags inside MP3 files:

Info: AllDup also ignores ID3v2 tags at the beginning of the MP3 file that exists twice and ID3v1 tags at the end of the file that exists twice.

Ignore metadata of JPEG/CR2 files

With this option, only the compressed image data inside files with the extension "JPEG", "JPG" and "CR2" will be compared.

Ignore metadata of FLAC files

This option enables you to ignore all the metadata inside FLAC files.

First compare a data block at the end of the files

With this option a data block at the end of both files will be compared first. The file comparison will be stopped if the data blocks are not identical. Otherwise AllDup continues the file comparison at the start of the file.

Block size of the read buffer

This option enables you to change the block size of the read buffer for the content compare.

The file comparison starts with a block size specified by the start value.
AllDup reads the block size from the two files into the memory and compares them.
The file comparison will be stopped if the data blocks are not identical.
Otherwise the block size will be increased by the increment value until it reaches the maximum value and continues comparing the files (2).