About webminster

So first I'm no expert on the subject, only an A/V amateur who watches way too much video.  And bought some good mid-scale (not "professional grade") equipment because of that.  And, needs a decent quality signal to make the investment worth it...   That said, part of the deal is is subjective.  Comcast eludes to that in their releases that they had feedback from many focus groups to arrive at their strategy.   I'm sensitive to video issues, dithering, macroblocking, pixelation, what-not.  My wife, on the other hand, not so much... I see something and say "what was that?"... she says, "what?".   So much of what Comcast has done revolves around the majority of customers who can't, for whatever reason, see the difference.   Speaking from my view only, the amount of discomfort, if any, in the past from deinterlacing artifacts on the various monitors and STBs I've used is minor compared to the post-migration changes.   Right after the migration, I could see the loss of detail, and the dithering.  call that what you will, but from my (subjective) perspective, the "cure" for any perceived deinterlacing issues is far worse.   Many people on other threads (like at DSLReports) also feel the same, FWIW.   One positive - before the migration, a lot of channels were encoded my Comcast with a switching interlaced/progressive format (the signal rapidly changed back and forth).  In Windows Media Center circles, we referred to the syndrome as "29/59" and it could drive a video card nuts (only some video cards did a decent job coping with it).  Even then, sometimes you could see some "shimmering" on channel ID bugs.  Since the migration, those channels are now stable since they're re-encoded as pregressive, no switching.  But it's a 1-forward-1-back situation - the bugs are stable, but the picture is softer and you can see dithering on some channels on occasion.  My choice?  Hard, but I'd take the former.   I suspect all the deal with progressive and deinterlacing still matters more for the streaming end.   Is Comcast trying to unify their signal so they don't have a mobile-optimized and a home-TV-optimized delivery, just one?  Since deinterlacing on phones and tablets is much worse that consumer-TV equipment, perhaps.   Comcast keeps me out of the loop on their strategic plans. ... View more

I've seen discussions elsewhere about SD, dropping it or compressing more... my understanding is the SD bandwidth usage is pretty low as is (and the quality already bad enough), that more compression won't gain much.   I'd accept dropping the SD channels - if there were HD replacements.  Unfortunately there's a lot of SD channels (take TVLand) that Comcast doesn't carry in HD (at least here).   I've seen arguments that Comcast could drop SD channels where an HD equivalent exists, and have the CP equipment downscale and convert the signal for old TVs.  Not sure if practical in practice...   ... View more

There's no end of arguments from Comcast and supporters that we're better off.  Personally, with my 65" OLED set and decent equipment, I disagree, since I can see it.   I'd say your premise could be true (the "professional-quality deinterlacing"), if we knew that to be the case.  The only best way here is 720p from the source, not Comcast re-encoding the signal.   Still stand behind the last premise though... As long as Comcast is going to drain all the bitrate out of the signal, overcompress it, the game ended before it started.  No amount of upscaling or other CP-end signal processing can restore the lost detail. ... View more

People can argue the veracity of 720p vs 1080i.  But there's points that have to be kept in mind:   * 1080i can have deinterlace problems.  But a decent contemporary deinterlacer can do a good job.  However, mobile devices don't tend to have good capability here, so the progressive format works better if you want to play on mobile devices, or try to least-common-denominator your streams to work on both mobile and TV devices.   * 1080p would be holy grail.   However the bandwidth requirements for cable companies to do 1080p given current plants is not practical (without implementing SDV, or dumping traditional TV delivery for something like IPTV).   * 720p does, or course, drop about 55% of the pixels compared to 1080(i/p).  If you have a native 1080 or 2160 (4k) display, of course those pixels have to be interpolated (synthesized).  Stipulation, if you have a display and STB that uses directly the 720 signal... but the pixel mapping still has to happen.   * The critical issue... is less the 720p part.  720p can look good, and upscale well - IF the source encoding is very good.  Comcast is overcompressing the signal during the MPEG4 conversion, and reducing the bitrates on the program to just barely good enough.  MPEG4 compression works based on a quality/compression ratio - the more quality you can sacrifice (e.g. fine detail), the more bandwidth you can save.   Comcast has compressed the signal to death to cram more channels together in a QAM.   The loss of fine detail, and in many cases the dithering you can see during scene transitions, I believe are rooted in this.   That last part was not publicized as part of the MPEG4 migration (actually, few details were).  But it's the part that causes customer dissatisfaction.   Other systems (like DTV) do MPEG4 as well - but they don't bitrate-starve the result so badly, and the picture looks better. ... View more