Ogg streams must include unique serial numbers. See Ogg bitstream overview for more details.

By default oggenc includes random serial numbers in the header, which are seeded by the current time and the pid.

Detection

Example debbindiff output

Solution

oggenc has a -s option to force a specific serial number in the output stream. This can be prevented with oggenc -s. Watch out for duplicates in case of chaining or multiplexing.