PHP version of ExifTool libraries

[Phil Harvey]

Hi Marcel,

However, I found out that php's json_decode() not always decodes the generated json correctly.

I ran some tests and find that this will happen if any of the strings are not valid UTF-8.  I knew that exiftool could produce invalid UTF-8, but didn't know that this would break a JSON parser.

I will change this in version 8.76 to replace invalid UTF-8 characters with "?" (incurring a small performance hit), which should solve the PHP json_decode() problem.

- Phil

Edit: Searching through the forum, I found this thread, where the JSON problem was exactly described to me.  I had forgotten about this.  Unfortunately, that thread didn't progress until a solution was found because we were looking specifically for a solution to the encoding of filenames, and a general patch like this to fix random UTF-8 errors wasn't suggested.