CEDAR Duo – declickle and auto dehiss
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Unfortunately, interpolating each impulse using a basic declicker is not satisfactory because of
the fundamental nature of the crackle. A standard click-detection algorithm will miss smaller
impulses, and it will fail to cope with the high density of those impulses. Furthermore, standard
declick algorithms assume that a click or scratch has totally corrupted the audio and that there
is no useful information about the signal during the click. Since the disruptions that cause
crackle are very small they may be considered to be additive, and this assumption is no longer
appropriate. Declicking a crackly signal discards a lot of useful information that an optimal
algorithm can use to improve the quality of the processed audio.
Declickle
CEDAR's Declickle algorithm was born out of research into the dual problems of declicking and
decrackling difficult signals such as those including overblown brass instruments, solo strings,
and human singing. In attempting to solve these difficulties, our researchers discovered that a
single, new algorithm yielded better results than applying separate declick and decrackle
processes. The performance of the resulting module is so good that, in almost all cases, it is not
possible to hear that the signal was damaged prior to restoration.
