A lot of effort goes into making sure that the episode of America’s Funniest Home Videos you watched last night was as pristine as possible. From the network’s broadcast center to your local TV station’s transmission tower to that antenna on your roof, and finally to your DVR, a number of mechanisms ensure that all those 1s and 0s in the digital broadcast get to you unscrambled and in the right order.
But from time to time lightning storms, swaying trees, and stray cats will wreak havoc on the signal. Filters, error detection and correction codes, and even the most elaborate incantations of RF engineers struggle to make sense of the distorted waveform being received. Inevitably the occasional glitch sneaks past and you end up recording some damaged audio and video. The last bastion of defense for couch potatoes lies in the MPEG decoder and player’s ability to try to make some sense of the damaged programming. In many cases some sleight of hand can mitigate the visual effect of the damage, and occasionally the errors can be concealed so well that they’re invisible to the casual viewer.
We’re going to focus in this article on error concealment of MPEG-2 video. But the general principles apply to other video compression schemes such as H.264 and H.265.
There’s been a lot of chatter about interlaced vs. progressive video and how progressive video is inherently superior. Interlaced video, in comparison is said to be Just Plain Evil. Perhaps it’s my analog video background, but I have a far more favorable view of interlaced video.