HDMI video transport

HDMI video transport carries a selected presentation signal between source and sink, with accompanying audio and signaling distinct from the compressed media delivered to the player.

In a typical Emby setup, the server delivers encoded media to the client. The client decodes and prepares a presentation, then its HDMI output sends a selected display signal to a TV or receiver.

The cable ordinarily carries that presentation signal, not the original movie container or its HEVC/AV1 bitstream.

Two connections carry different representations

Connection Representation in the ordinary playback route
Emby Server → client Encoded media through the chosen delivery method
Decoder → renderer Reconstructed picture resources and their timing/color meaning
Client HDMI output → display input Selected picture timing, sample representation, audio and signaling

The network bitrate and HDMI link rate therefore describe different data.

For an original 3840 × 2160, sixty-picture/second RGB exercise with eight bits per component, active picture samples alone require:

3840 × 2160 × 60 × 3 × 8
= 11,943,936,000 bits/second

This is about 11.944 Gbit/s before the transport’s timing, coding and other overhead. A source file encoded at twenty Mbit/s is about 597 times smaller by those two declared rates.

The calculation is an active-sample model, not an HDMI mode qualification. Link bandwidth adds the transport relationships.

The selected signal has several properties

A mode needs more than a resolution label:

Property Example question
Picture timing Which dimensions, refresh rate and timing totals are selected?
Sample representation RGB or YCbCr, with which chroma arrangement and precision?
Color interpretation Which primaries, transfer function and range describe the output?
Link arrangement Which supported TMDS or FRL configuration carries it?
Companion information Which audio and required signaling are supplied?

A device can use a high-resolution output for a lower-resolution movie because the client scales the picture into its established output mode.

Conversely, delivering a 4K movie does not prove that the client sends a 4K HDMI signal. The selected local mode may be smaller.

Source, sink and intermediate devices participate

The output device is the HDMI source for this connection. The receiving input is its sink. A receiver or switch can add another input/output relationship.

Capability information helps the source choose a mode, while the link must successfully establish and carry that choice. A mode supported by the TV alone may not survive an intermediate device or a particular port arrangement.

EDID describes declarations. AV receivers explains the two-link route. Handshakes separates mode choice from active signal progress.

Picture transport has separate companion functions

HDMI can carry audio alongside the video presentation. ARC/eARC provides an additional return-audio relationship from a TV toward an audio system.

CEC carries control messages. HDCP addresses protected-link authentication. HDR signaling communicates relevant output interpretation.

See Also

References