In the old version (0.3), I found that if I use svg-sprite-loader at a PNG file, then the PNG will be convert to a svg with embedded BASE64 <image> tag.
https://github.com/kisenka/svg-sprite-loader/blob/v0.3.1/lib/processings/raster-image-to-svg.js
While in the latest version, this feature has been removed.

I wonder how can I get the same functionality in version 3.2 ? Do I have to use anthor loader, just transform PNG to svg, like this:

PNG  [Some loader]->  SVG  svg-sprite-loader->  sprite.SVG