problem with escaping "

Hello,
I've created a new type in C, with the following structure:

typedef struct movie_property {
int4 length;
int4 id;
char name[31];
char value[256];
} movie_property;

I did the functions for the input, parsing and output, but one problem
apears.
If I try to insert some text with " inside, I try to escape it with a \
(in fact, I'm doing this from php, with its function "addslashes")

INSERT INTO pp VALUES ('(1, "aa \" bb", "fghij")')

But I get an error:
Bad movie_property external representation '(1, "aa " bb", "fghij")'

which means that my movie_property_in function receives the string
'(1, "aa " bb", "fghij")', without the \ in it.

The same exact thing works for varchar or text fields.
What can I do ?