Coaxial output
In this case, the term
coaxial refers to a type of SP/DIF interface that uses an electrical cable with an RCA connector. This interface provides sound transmission, including multichannel, in digital format; at the same time, the electrical cable is more susceptible to interference than the optical one, but is not as fragile.
Optical output
A variation of the SP/DIF audio interface that uses a TOSLINK fibre optic cable. Like the coaxial connector,
the optical output uses a digital data transfer format and can work with multi-channel audio. At the same time, optical fibre requires rather delicate handling, but it is absolutely insensitive to electrical interference.
CPU frequency
The clock speed of the CPU installed in the media centre.
On the technical side, the higher this indicator, the faster the processor works and the higher, accordingly, the overall system performance. At the same time, the CPU performance depends, in addition to the frequency itself, on a number of factors — architecture, number of cores, special design features, etc.; and the actual speed of the entire system is affected by performance of components other than the processor. In addition, manufacturers usually select processors in such a way that their computing power is guaranteed to be enough for all the features claimed for a media centre. Therefore, in this case, the CPU frequency is more of a reference parameter (and partly an advertising indicator that demonstrates the advanced specifications of the device), rather than practically significant for buyer.
Ultra HD 4K support
The ability to play video in
ultraHD 4K on the device. This format covers several resolutions, all of which have a horizontal size of approximately 4000 pixels. However, the most popular is the frame size of 3840x2160 — in particular, this is the standard value for 4K TV screens; therefore, most UltraHD content is also released in this resolution.
A 3840x2160 frame contains 4 times more pixels than the popular Full HD standard, resulting in an even sharper and more detailed image. Of course, you will need a TV (or other screen) of the appropriate resolution to fully enjoy the experience; but such screens nowadays are becoming more common and affordable.