When a HDMI / HDCP Handshaking issue occur the easiest way to re-negotiate the handshake is to power cycle the source device or the display. Always wait 10 seconds or longer when the display or source has been power cycled for the HDMI distribution equipment to reset hdmi handshake / timing. Some displays may also re-negotiate the handshake when swopping to another input e.g. AV1 ,AV2 or another HDMI Port (wait 10 seconds) and swopping back to correct HDMI Input via remote control. HDMI Distribution equipment should never be powered off since it provides the path for the HDCP / HDMI Handshake between source and display.
Some devices such as switches and HDMI Switches / Combo splitters also allow for HDMI handshake re-authentication by switching from one input to another and back to the input having HDCP handshaking issues. If power cycles on the Display or Source does not prove to be effective power cycle all HDMI equipment (Source, HDMI Distribution Equipment, Receivers / Amplifiers and Displays). If HDCP errors still occur you need a firmware upgrade to sort out the HDMI port timing / handshake issues on the source or display. Please contact your Source device, Display or Digital receiver manufacturer for a firmware upgrade and advice on hdmi handshake issues. It is often extremely difficult to troubleshoot these issues since the HDTV supplier will blame the source supplier, will blame the digital receiver supplier, will blame the Hdmi Distribution supplier etc. etc. If going through your total home entertainment setup, make sure all your equipment has the latest firmware.
Most HDMI Distribution equipment also feeds voltage from the HDMI Ports on the LCD's and sources. When all equipment has been power cycled and BEFORE LCD's / Sources are powered on again ensure that the HDMI Distribution equipment is also power cycled by unplugging / plugging both the power AND the HDMI cables connecting to the equipment which provides power for it to be completely powered off.
Digital sparkles occur because of transmission / bandwidth issues. Check to ensure that high quality Category 5, 6 or 7 networking cables are used on extender sets between sender and receiver units. CAT5/e Unshielded is not recommended and not supported at all, CAT6/ CAT6e Unshielded up to 40 meters (if no electrical interference nearby), CAT5e Shielded up to 30 Meters, CAT6 Shielded up to 50 Meters and beyond 50 meters up to 65 Meters CAT7 (All pairs shielded individually) 10 Gbit/s cabling needs to be used. The maximum transmission bandwidth on HDMI CAT6 / CAT7 Extenders are 10.2Gbps and 2 x 10Gbit/s CAT7 cables will achieve the transmission bandwidth required and HDMI v1.3 resolutions and capabilities.
Digital sparkles can occur by coupling or extending HDMI cables beyond the recommended 18 Meter Lengths on 24AWG Category 2 rated cables. If using 28 AWG cables and digital sparkles occur switch to a lower resolution or use 24AWG Category 2 cables for higher bandwidth transmissions over longer distances.
Usage of Unshielded Twisted Pair (UTP) cables are not recommended with HDMI or any video / audio equipment over CAT5e / CAT6. The usage of grounded cable FTP (Foil Twisted pair) or STP (Shielded Twisted pair) are mandatory to ensure CAT5e / CAT6 is grounded properly and best signal transfer is done via STP / FTP cable for syncing video/audio TMDS channel on HDMI.
Another cause of digital sparkles on HDMI Extenders / Baluns is when the CAT5e / CAT6e cabling is not inserted into the ports correctly, hanging from ports or skew inserts due to incorrect fastening / securing to a surface. Push the cables (even when it clicks into place) another 1-3 millimeters inwards to ensure it makes a secure connection with the pins to transfer the signal properly.