Need to figure out how to handle os.Exec() on WIndows, need to figure out what the case is with getting current rsvg-convert and pngquant on Windows.

For SVG (XML) it would be highly desirable to be able to do some XML parsing to find an SVG tag somewhere and possibly also to extract more data such as height width and color format.

For MKV and WebM (MKV derivative) the format EBML is used. It seems that there are no other EBML users aside from that we would ever need to worry about but a really tiny EBML parser that just looks for DocType (format string).
This is a required top level element spotted by EBML ID 42 82.

Width height etc extraction would be less viable for the EBML using formats as they are container formats.

Future formats to add

OGG

• Vorbis
• Theora
• Opus

MP4

• H264
• H265
• common audio codecs

Webp

• /x/image package