Currently, many consider K2 Technology to be data-processing high-quality sound technology (upconverting technology), however upconverting is a part of K2HD Processing.
With K2HD Processing, it is possible to restore degraded digital sound sources caused by compression to high-resolution sound quality level equivalent to uncompressed CD quality or original masters.
For instance, more than 20kHz is lost in CD format if a CD master is created from an analog tape master. That high-frequency component lost in the conversion process can be restored to nearly identical as the original analog master.
The development of K2 Processing started in response to calls from studio engineers who wanted the sound quality of CD masters restored to their original state. Because a CD Master (44.1 kHz/16-bit) is recorded in the form of digital data like a CD, sound data higher than 20 kHz is not recorded. K2HD Processing was developed with the aim of restoring sound and music sources to their original state for legacy content where only the CD master remains today. The technology is also helpful in creating high-resolution sound sources from a CD master.
*1: Sampling frequency: The number of samples per second in sound that is acquired when an analog signal is converted into a digital signal (AD conversion).
*2: Playback frequency: Sound frequency that can actually b e played back. The value of the playback frequency is half the sampling frequency. In order to playback the humanly audible frequency range of 20kHz, CDs sample analog sound at 44.1 kHz
K2HD Processing is a high-quality sound technology made possible by processing digital data that is derived from one of the fundamental principles of K2, “to restore or return to the original state”. Degraded sound sources, which are created by compressing the sound source or converting to a limited format or specs, can be restored to a quality equivalent to the original master. Up to 192 kHz high-frequency range extension (for CD sources: Expands playback frequency from 22.05 kHz to 96 kHz) and bit extension or minute signal extension (for CD sources: bit rate is expanded from 16-bit to 24-bit) are applied to create timbre equivalent to the original and the power needed for sound expression.
Harmonics is a key element in timbre. The sound of both musical instruments and voices are composed of multiple frequencies, and the lowest-frequency sound is called the“ root”.
Frequencies that are integral multiples of the root are mixed to create timbre.（ Musical instruments produce different timbre even when playing the same frequency because of differences in harmonics.） With CDs, analog sound is converted into digital sound using a sampling frequency*1 of 44.1 kHz; thus its playback frequency*2 will be up to 22.05 kHz and overtones（ harmonics） in higher frequencies are eliminated.
The original algorithm（ waveform correction process） featured in the high-frequency range extension in K2HD Processing that utilizes the expertise of Victor Studio, restores cut-off harmonics in the high-frequency range from the remaining sound to reproduce music expression equivalent to the original master.
Tone control of K2HD Processing technology is developed through rounds of audition checking performed by studio engineers at Victor Studio, a cutting edge facility for professional music production.
Sound quality adjustment, performed jointly by the studio engineers who are familiar with the sound quality and musical quality, is performed repeatedly over in all the main genres stored at Victor Studio. K2 parameters consisting of multiple items related to sound quality are then carefully selected from about 4 trillion combinations.
K2HD Processing boasts a high degree of perfection not only in terms data characteristics and technological aspects but also in actually audible sound quality and musical aspects.
Even if another manufacturer were to succeed in developing a program similar to K2 by referring to the information available in the patent document, it will never be possible to emulate the parameter setting values based on 4 trillion combinations. This is the true essence of K2, an innovation between people and technology that can only JVCKENWOOD could achieve.
When converting an analog signal to a digital signal, the number of steps to reproduce the loudness from silence to maximum volume affects the expressiveness of music such as its smoothness and subtlety. CDs express from silence to a maximum volume in 65,536-step resolution because it is 16-bit (2 to the power of 16). However, 16,777,216-step resolution can be achieved with 24-bit extension, allowing reproduction of minute signals not heard on CDs for music with a large volume differences like classical music, to reproduce realistic sound full of ambience such as breath and fine details of strings. With K2HD Processing, Victor Studioʼs expertise is added as a variable to this bit extension to achieve more natural, smooth sound.
K2HD Processing is not a simple up sampling / bit extension (conversion) for high frequency bands or minute signals of degraded / deteriorated digital sound sources; rather, it is capable of restoring the sound quality equivalent to a master sound source by applying Victor Studio engineersʼ sound creation expertise into the extension process. When K2HD Processing is implemented, it is possible to achieve sound faithful to deliver “the sound the artist intended” even for compressed digital sound sources.