A method of adding auxiliary data, e.g., audio data, to a high-speed serial video
link in such a way that it is invisible to existing receiver and such that auxiliary
data, e.g., audio, can be transmitted without any knowledge of the capabilities
of the display to receive the auxiliary data. Some of the DC balancing bits are
used to transport the auxiliary data information over the link in a manner that
does not change the data recovered by a DVI-CE receiver, or a legacy receiver (installed
base). DC balancing is also maintained, but with differences over known techniques.
Since the auxiliary data bits (which are occupying the time slots of the DC balance
bits) will be interpreted by legacy receivers as DC balance bits, the data must
be optionally inverted to remain consistent with the value of the auxiliary data
bit being transmitted. The DC balance bit that is transmitted at the beginning
of each group of four words must also invert the value of the auxiliary data to
allow the DC balancing to be achieved independent of the auxiliary data.
