Since this change removed the _getxmp function - which I used in pillow_heif, could you at least add parsing for the NULL terminating byte in xmp? @radarhere

Info is here:

bigcat88/pillow_heif#69
AOMediaCodec/libavif#1333 - topic is big, but most important are last messages

Because now I need to either remove the leading byte, which will lead to the fact that if the image is opened and saved, the xmp will differ in a result by that one byte.

That will allows me to just remove getxmp from pillow_heif, otherwise I will need to copy old _getxmp code and use it..