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'Q-Spoiler' is a method to plug the Analog Hole which inserts data into digital audio files that is inaudible as long as the file is played “as is.”
Added after 9 minutes:
Q-Spoiler also prevents conversion through codecs, e.g. CD to MP3 for P2P
file swapping. Therefore preventing the creation of MP3 or WAV files that
can be then loaded to the Internet.
Added after 6 minutes:
Unlike existing CD copy protection, which tries to make CD music files invisible or unreadable to computers and other copiers, Darknoise(UK company) actually modifies the audio of the songs slightly. If those songs are then copied--even by holding a tape recorder in front of a stereo speaker--the formerly inaudible Darknoise addition becomes audible and makes the copy unlistenable.
This looks like they put an ultrasonic tone into the signal which makes IMD products with the recoding or the bias oscillator on analog tape recorders. This will be very easy to overcome by putting a notch filter in the analog line or by the equivalent in the digital processing domain.
A similar effect occurred in the early days of broadcast stereo in the US. The subcarrier reference oscillator would mix with the tape bias oscillator and produce an audible tone in the recording. This was cured when the new lines of recorders had a higher frequency bias oscillator frequency.
This method will have a very short life just like the Sony method that was countered with a marker.