jpg file difference : from wireshark tcp stream and from a C++ socket

Question

I'm trying to record a jpeg image sent by an Ethernet camera in a mjpg stream. The image I obtain with my Borland C++ application (VSPCIP) looks identical in Notepad++ to the tcp stream saved from the application Wireshark (except for the number of characters : 15540 in my file, and 15342 in the wireshark file, whereas the jpeg content-length is announced to be 15342). That is to say that I have 198 non-displayable characters more than expected but both files have 247 lines.

Here are the two files : http://demo.ovh.com/fr/a61295d39f963998ba1244da2f55a27d/

Which tool could I use (in Notepad++ (I tried to display in UTF8 or ANSI : files still match whereas they don't have the same number of characters) or another editor) to view the non-displayable characters ?

Answer 1

std::ofstream by default opens the file in text mode, which means it might translate newline characters ('\n' binary 0x0a) into a carriage-return/newline sequence ("\r\n", binary 0x0d and 0x0a).

Open the output file in binary mode and it will most likely solve your problem:

std::ofstream os("filename", ios_base::out | ios_base::binary);