Download of sub2srt 1.0 for Mac was on the developer's website when we last checked. We cannot confirm if there is a free download of this app available. This free Mac app is a product of Bojan. Please check the Mac app with an antivirus before launch as it is downloaded from the developer's website, and we cannot ensure that it is safe. The software belongs to Audio & Video Tools.
From the developer:
sub2srt is a Python script designed to help you convert subtitle files that use the .sub file format to the .srt standard. First, you need to open a Terminal window and navigate to the project's folder. The next step is to run the sub2srt Python script and get the usage details: sub2srt-python input.sub output.srt fps. Then, you need to employ the command line to run the script and then provide the appropriate parameters.
You may want to check out more software for Mac, such as MFilter, Aiseesoft WMV Converter for Mac or AkBrowser, which might be similar to sub2srt.