[charleslmunger]

Yes, but when when there's signal degradation in an HDMI cable it shows obviously, not as a subtle video quality change. If you can see an HDMI signal with white blinking dots everywhere, you can be confident that the cable is not altering the signal in any really detectable way.

[chaboud]

"If you can see an HDMI signal with white blinking dots everywhere, you can be confident that the cable is not altering the signal in any really detectable way."

I have seen an HDMI transmission with white blinking pixels at content edges that were not from the original signal. I ran test signal through that source and verified the errors on an HDMI waveform monitor, after which I tested the cable and threw it away.

HDMI video is not magically impervious to error because it is digital. It's actually a pretty straightforward transmission scheme.

This was while working on an HDMI-output device, working with team members who had written the original HDMI specifications (so, yes, I've read them).

It is possible to have subtle degradation in HDMI-delivered content. It's rare, but possible. As one might expect, comprehensive failures (e.g. black screen, periodic HDCP key mismatch) are far more common, as are negotiation/configuration failures (e.g. wrong resolution, wrong framerate, wrong color space).