3. Content Protection (HDCP)

HDMI has licensed a built-in copyright protection called High-Bandwidth Digital Content Protection (HDCP), which was created by Intel Corporation for protecting movies and other programming from theft. HDCP is required on HD receivers or DVD/HD-DVD/Blu-ray players and recorders that use HDMI.

HDMI A/V Receivers

If you follow Home Theatre audio at all, you have no doubt heard that the latest thing you just "must have" is an HDMI-enabled A/V receiver. These receivers have HDMI inputs and outputs that provide the following capabilities:

Multi-channel audio and video - With an HDMI receiver, you can run one HDMI cable from video sources (such as an HD disc player or HDTV cable box) into the receiver input, and another HDMI cable from the receiver output into the HDTV display input. This will allow the video signal to go from the disc player/cable box to the HDTV and the multi-channel audio from the disc player/cable box to the receiver, where it will be output to the speakers. With non-HDMI A/V receivers, you would have to run a separate audio cable(s), such as optical or coaxial digital cable, from the disc player/cable box output to the A/V receiver input. While there might not be much difference in audio quality between HDMI and a separate digital audio cable to most listeners, it does consolidate at least one cable in your system.
Honestly, the benefit of this configuration is not that substantial if you only have one HDMI-based video source in your system. The benefits start to become more substantial as you add more HDMI components in the future, which will allow you to take advantage of..... HDMI switching - Most HDMI receivers currently available contain either 2 or 3 HDMI inputs, which allows you to connect multiple HDMI video sources to the receiver, and only one HDMI cable from the receiver to the HDTV display (some of which only have one HDMI input). You can then switch from one video source to another via the receiver control, as opposed to manually plugging and unplugging HDMI cables from the back of your HDTV or video source(s). This feature will become more important as greater numbers of components become HDMI-based. Analog- to-digital video (up)conversion and deinterlacing - Early releases of HDMI receivers kept digital and analog video signals separate, which would require analog A/V connections from the receiver to the HDTV. However, many current receivers convert incoming analog A/V signals (such as component or S-video), so all signals are output through a single HDMI cable. In addition to conversion, some receivers also deinterlace video signals (from 480i to 480p) - this can be a crucial feature, as some older HDTVs do not accept 480i signals from an HDMI connection. Some of the newer receivers even upconvert all 480i signals to 720p, 1080i, or 1080p, which should improve the appearance of older video sources when displayed on a newer HDTV.