Question for Engineers or GMs about Subchannels

[Rick_EE]

So in short, the motion artifacts I see are TWC's fault and not TMJ's?

[techboy]

Well yes, I'd say any TWC compression artifacts are of their making.  I just don't know how bad they are compared to OTA as I don't have TWC.  I used to have my own 12 foot satellite dish and watched the C band feeds.  They were compression artifact free.  There will always be some issues when converting raw HD video to Mpeg 2 or 4.  Each has it's own set of psychovisual issues.  But each is also capable of producing perfect pictures if a high enough bit rate is used.  The reason we get bad or marginal picture quality ( OTA or Cable ) is because someone has decided that it's acceptable to the general public and put too many channels in too little bandwidth.   It's a management decision based on monitary returns.  More low quality channels attract more customers and thus make more money than a fewer high quality channels.

[tencom]

In my measurements both both TWC and OTA, WTMJ-TV HDTV are both at about the same data rate,  with TWC using QAM 256 and when comparing side-by- side both OTA and TWC, are showing the same motion artifacts with TWC slightly lagging channel OTA, and  indications  that HDTV is  bit starved.