Overview: Capability negotiation and signaling
Display signaling coordinates capabilities, protection, control and other functions around the carried video signal.
An EDID exchange, an HDCP check and a CEC command perform different jobs. Audio return and quick mode switching add further negotiated relationships. This area separates those functions, providing useful checkpoints for a black screen or an unexpected mode change.
Capability exchange
Capability exchange describes the signal formats a receiving path reports and the metadata used to interpret them.HDCP
HDCP authenticates supported display-link participants and protects audiovisual transport under the applicable content and output policy.HDMI-CEC
HDMI-CEC carries device-control messages on a control path whose addressing and application handling remain distinct from HDMI picture and audio transport.Audio return channels
HDMI audio return channels provide defined routes for audio to travel back from the television side of a connection.Quick Media Switching (QMS)
Quick Media Switching uses a supported HDMI variable-refresh mechanism to reduce interruption during compatible frame-rate changes at a retained resolution.HDMI handshakes and black screens
HDMI establishment involves capability exchange, a compatible output choice, transport progress and any required signaling/protection relationships whose failures can produce similar visible symptoms.