This is a tool to convert SVG SMIL animations into rasterised PNG frames. I made it after making some animated SVGs and then finding out that I had no way to export them into a form that I could easily use.
You can access an instance of the tool online here at my website. Or, if you prefer, you can clone this repository yourself and host it locally.
Then open up index.html in a browser, select the file, set your parameters, then press convert. The SVG should be processed and a ZIP file containing a PNG for each requested frame should be downloaded soon after.
If you're having issues, please check the console log. If the error states that your XML is not well-formed, you may need to re-export your file formatted as a more compatible SVG, if possible.