I'm looking for a JavaScript library that allows you to add XMP metadata to JPEGs created with canvas.toDataURL(). I assume they don't have any metadata included, so it's about rebuilding the JPEG binary data with proper EXIF blocks added - as XMP is on top of EXIF.
All I could find are EXIF readers, but no writers.
Do you know any such libraries, or best candidates for porting in other languages?