Since HDMI is a digital signal with different ‘bits’ for audio and video, the signal can be sent to various devices. A particular device recognizes and picks off the bits that it needs and either passes on or ignores the rest. Carrying the video and audio in the same bundle of cable digitally will not cause the same problems as trying to do so in the analog realm.

The length of any data cable run can be extended to a fair degree by making the cable out of ‘better stuff’ than the standard light-duty multi-conductor cable or even further by using ‘converters’ of some type.

Back in my ancient work history, trying to carry RS-232 serial digital control data over long runs was problematic because RS-232 is an ‘unbalanced’ connection format. If enough hum, noise or signal degradation took place, the gear on either end would not be able to recognize the data. To extend the run, we would either break out the connector to individual, multiple BNC connectors and use high quality coax instead of the usual serial cable, or convert RS-232 to RS-422, RS-422 being a ‘balanced’ connection format, run the cable for a good ways, then convert back to RS-232. This conversion process did not convert the data in any way, only the cable format. In extreme cases, we could use converters from wire to optic fiber and back again.

The HDMI data is certainly transfered at higher rates than the old serial contral data I was using, but similar principles apply in getting the signal from point A to point B. In any case, long run HDMI cable may not be an off-the-shelf item in consumer stores, but there are bound to be ways to accomplish long runs for projectors or other gear that will not compromise the integrity of the data being carried.