Samsung LNT4669F Training Manual page 148

What is HDMI?
Link Architecture
As shown in an HDMI link includes three TMDS Data channels and a
single TMDS Clock channel. The TMDS Clock channel constantly runs
at the pixel rate of the transmitted video. During every cycle of the
TMDS Clock channel, each of the three TMDS data channels transmits
a 10-bit character. This 10-bit word is encoded using one of several
different coding techniques.
The input stream to the Source's encoding logic will contain video
pixel,
packet and control data. The packet data consists of audio and
auxiliary data and associated error correction codes.
These data items are processed in a variety of ways and are presented
to the TMDS encoder as either 2 bits of control data, 4 bits of packet
data or 8 bits of video data per TMDS channel. The Source encodes
one of these data types or encodes a Guard Band character on any
given clock cycle.
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