They are command line tools that preprocess a file before it is loaded for comparison. The first argument is an input file and the second argument is an output filename. As an example, the pdftotext.exe tool extracts a .pdf file to a plain text .txt file, then displays the temp file in Beyond Compare's Text Compare.
See Beyond Compare's help file topic Text Format Conversion Settings for details.
Answer from Chris Kennedy on Stack OverflowThey are command line tools that preprocess a file before it is loaded for comparison. The first argument is an input file and the second argument is an output filename. As an example, the pdftotext.exe tool extracts a .pdf file to a plain text .txt file, then displays the temp file in Beyond Compare's Text Compare.
See Beyond Compare's help file topic Text Format Conversion Settings for details.
In another question (Compare Json Files in Beyond Compare ) I walk through a step by step example that demonstrates some json conversion for diffs to lend a concrete example to this question. What Chris said above is spot on, it's basically a console application that uses some fixed argument positions to take in the input file path as well as an output file path that the text representation will be written to.
$myConvertingConsoleApp $inputFilePath $outputFilePath
Beyond compare will actually provide the actual arguments used by the console application during the conversion process.
It's worth noting that the input file need not even be a text file so long as you can come up with some sane textual representation of the file format that makes sense for diff algorithms to operate upon.