In the description of technical characteristics both expensive categories, for a couple of thousand dollars, and in budget categories, such as top A/V receivers under $500, mentions of 4K (UHD, Ultra HD) signal pass through is increasingly common. This mainly applies to 4K video. Let’s figure out what kind of technology it is.
What is the signal pass through?
The term “video pass-through” means that the receiver is capable of receiving an input signal from an image source and sending it to a compatible display. But there is one prerequisite, the HDMI port must be HDCP 2.2 copy-protected in order to pass the copy-protected video signal, which will include all commercial content for home viewing. The receiver’s HDMI output connects to a display (TV, monitor, video projector), which must also support HDCP 2.2.
If the receiver has only one HDMI input with HDCP 2.2, it will only pass the native 4K / UHD signal from the UHD player or UHD streaming device.
Also, in addition to the image, an audio signal is transmitted. By connecting a source such as Blu-ray player to the receiver`s HDMI pass-through port, you get quality sound in Dolby True HD and DTS Master Audio.
How to use HDMI pass-through
Such video pass-through function allows signal passing through the receiver without changing the image quality. The home theater receiver with HDMI pass-through function plays 4K signals from the source device on 4K compatible TV or projector while maintaining source quality.
For greater clarity, you can imagine a chain of devices that are needed and the result:
- 4K video signal source, for example, a BlueRay player;
- AV receiver with the necessary set of functions;
- 4K compatible projector or TV;
- high quality HDMI cable;
- 4K image, which is broadcast without quality loss.
There are some HDMI nuances that you need to know and take into account when choosing a receiver.
The vast majority of models now have only one HDMI input with HDCP 2.2 protection.
It is also worth remembering that the data rate is important for the pass through transmission. HDMI 2.0 can have a data transfer rate (bit rate) of 10.2 or 18 gigabits per second, but the specifications almost never indicate exactly what speed is used in its HDMI in or out. If it’s 10.2 gigabits per second, then the connection can carry a signal with a resolution of 2160p at a frame rate of 60 Hertz in 4:2:0 color downsampling and 8-bit bit resolution, which is not enough for a signal with high dynamic range (HDR).