PDF content are saved as several ways, "(abc) Tj", "(<0035><0035>) Tj" or "\u065".
I want to know if there is a way to convert the PDF code to one type, no matter direct text "(abc) Tj", or hexadecimal "(<0035><0035>) Tj", or Octal "\u065".
I think if convert and encode the PDF to one type, will be easier to analyse the content.
Is it possible to use Ghostscript or something to do that? Thanks
Essentially, no, there is no way to do so. There are two kinds of string, regular strings '(' and ')' delimited, and hex strings '<' and '>' delimited. Hex strings need not be escaped whereas regular text strings do need to be for 'special' characters, like carriage return and linefeed. Octal is also permitted in regular strings.
PDF producers are free to mix and match these all they like, but in general a given PDF producer will usually use one technique throughout.
Because Ghostscript's pdfwrite device is a PDF producer, it will (I believe) generally produce all its output the same way.
What it won't do is 'convert' your original PDF file. It produces a brand new PDF file which should look visually identical but whose internals bear no resemblance to your original PDF. In addition some metadata or fidelity may be lost.