是否有除Hex以外的PHP的字母数字字符串编码器？

I want to encode some binary strings with something like base64 but only with alpha numeric chars. I know bin2hex could do this, but it makes the encoded string much longer (i tries gzcompress in the strings but didn't make much difference).

Is there any other existing encoding method to do this?

http://en.wikipedia.org/wiki/Binary-to-text_encoding

The most used forms of binary-to-text encodings are:

• hexadecimal
• base64
• quoted-printable
• uuencoding
• yEnc
• Ascii85
• BinHex
• Percent encoding