Originally Posted by arnyk
This requires that digital data be changed in-steam by a passive device, in highly sophisticated ways. You are basically claiming that a cheap passive cable applied something like a Gaussian Blur in real time to a HD graphic that was running at 24 FPS or more.
Not only that, but the data is scrambled as NRZ coding. This has nothing to do with copy protection. The scrambling of bits is needed to reduce the DC content which makes clock retrieval difficult. When serial data rates get into the 100 mhz+ range, NRZ scrambling is mandatory. The SATA and PCIe busses used in your PC uses a form of NRZ coding. So based on this, any error, even a single LSB will cause complete loss of that word. Hence the sparkle and if severe enough in time it will cause complete clock loss.
In addition HDMI carries HDCP which is a key exchange protocol that further scrambles the data to make decoding the stream via a wire tap almost impossible. So again even a single LSB error will cause a loss of that digital word.
A further issue with HDMI is that it is really a quasi parallel interface. Rather than one single serial stream like SDI and AES/SPDIF, HDMI uses four pairs, RGB+CLOCK.. In this implementation, skew due to differences in the wire pair lengths is a problem at these frequencies. (Not a problem at all with your speaker cables!). This is what kills long cables on HDMI. Not the capacitance or amplitude loss due to too small a wire gauge which many boutique manufactures claim. Then why not use a single multiplexed stream? The only benefit of a parallel stream is the bandwidth required is cut by three in the case of HDMI.
And unlike packet based transmission like the internet and broadcast MPEG, there is very minimal error correction with realtime digital video transmission.
Bottom line no HDMI cable can make blacker blacks, more saturated colors, better 3D experience, etc. You either have errors or you don't. Errors are sparkles and dropouts. Sure, the same old analog parameters such as capacitance degrade the bit stream just as with any analog signal. The difference is the way in which the information is carried by the signal.
A serial digital signal like SDI, HDMI, AES, SPDIF, SATA PCIe, is basically just plain old FM (Frequency Modulation).