OTA HD channel quality vs cable HD channel quality

[RickStrobel]

Is there a noticeable difference in quality of the picture (or other issues) when comparing OTA HD signals that you pick up with an antenna vs relying on the signals that your cable company provides?

The cable installer told me that there was. His reasoning (as I understood it) is that the cable company gets their signal the same way I would if I had an OTA antenna. They just rebroadcast that signal to me over the cable system. In the process the signal degrades a bit and some bits are lost. The lost bits are filled in by the decompression algorithm when the signal is decoded and results in fuzzy edges (as an example).

I always thought that the explanation was that the cable company recompresses the signal.

Regardless of the explanation as to why, I'm curious about maybe getting and hooking up a good antenna if it might make a difference.

[Jerry_K]

How far are you from the local towers? If under forty miles I can recommend the Yagi available in store only from Radio Shack. $25 is worth it for a try.

[tubsone]

.

[moyekj]

Is there a noticeable difference in quality of the picture (or other issues) when comparing OTA HD signals that you pick up with an antenna vs relying on the signals that your cable company provides?

The cable installer told me that there was. His reasoning (as I understood it) is that the cable company gets their signal the same way I would if I had an OTA antenna. They just rebroadcast that signal to me over the cable system. In the process the signal degrades a bit and some bits are lost. The lost bits are filled in by the decompression algorithm when the signal is decoded and results in fuzzy edges (as an example).

I always thought that the explanation was that the cable company recompresses the signal.

Regardless of the explanation as to why, I'm curious about maybe getting and hooking up a good antenna if it might make a difference. In general the cable companies do not re-encode the signal. However they often do some bit-rate shaping when multiplexing the channel in along with others occupying the same QAM. So the result may be slightly de-graded bit rates compared to what you get OTA but in majority of cases you will not notice any difference between OTA and the cable co. re-transmission.

NOTE: This is certainly true in my case in Cox, Orange County, CA. I have both OTA and cable versions of the HD locals enabled and don't notice a difference between the 2 via my S3. I also have in the past captured OTA and QAM samples of the same program (from a PC capture card) and used TSReaderLite to examine the transport streams and the average bit rate of both were virtually identical (and resolution etc. was the same).

[msalmon]

I find a difference for rapidly moving scenes. A good example is the intro to NBC's Las Vegas (which has some high speed zooming/panning) - for me this usually is heavily pixellated by cable, and only slightly pixellated OTA.

[ashu]

Some minor pixelation differences during high motion and/or high frequency light-intensity variations (umm, essentially the same thing!) notwithstanding, my local cable HD has been impressive in a direct comparison with my OTA. And despite OTA being superior, it still is a smidgen unreliable with wind/rain ... so I am currently converting my original SPs (from my pre-CableCard weekend) over to cable.

[Tarek]

So am I the only one who is thus far unimpressed with the quality of the TiVo Series 3's HD tuners? For a while now, I have been a DirecTV customer using both a Sony HD200 receiver for HD and Philips 7000 DirecTivo receiver for DVR capabilities. I have always been nothing short of impressed with the Sony's picture quality for HD signals, for both OTA and DirecTV sources alike.

In the interests of upgrading my system, receiving more HD channels, recording HD programming, etc. and because of my dislike of the DirecTV-branded MPEG4-capable receivers, I bought the TiVo Series 3 and am giving cable (Comcast) a shot. While I'm still awaiting Comcast to install my service and provide CableCards (long sorry tale here - and I know I'm far from alone), I have been watching local OTA HD channels to get a feel for picture quality.

While I would like nothing more than to say that the picture quality is better than ever on the TiVo Series 3, I'm afraid that this is just not the case. From what I've seen so far, the picture quality on my old Sony HD200 DirecTV receiver is noticeably superior to that of the TiVo when comparing HD broadcasts. This appears to be the case in both OTA vs. OTA comparison and OTA vs. DirecTV comparisons. I never would have thought to see a compressed DirecTV HD broadcast appear superior to that of an uncompressed OTA HD broadcast! Both receivers were hooked up to the same HDTV via either DVI or HDMI cables. Based on both this and previous experience with cable, I'd imagine that Comcast's HD channels can only appear worse than what I've seen so far in OTA HD broadcasts viewed on the TiVo Series 3 receiver. It appears that I may have to make some tough decisions between HD quality (DirecTV w/Sony HD200) vs. HD channel quantity, TiVo capabilities, convenience, etc (Comcast w/Tivo Series 3).

Am I the only one in such a predicament? I've been scouring the forums, but so far have only come across others' positive comments regarding the quality of the HD tuners in the TiVo Series 3 receiver.

[phox_mulder]

Am I the only one in such a predicament? I've been scouring the forums, but so far have only come across others' positive comments regarding the quality of the HD tuners in the TiVo Series 3 receiver.

My experience is that the OTA HD tuners in the S3 are miles ahead of the ones in the HR10-250,
and maybe even better than the one in my 6 month old HDTV.

Perhaps you should be looking at the input rather than the output for the source of your quality problems?


phox

[DragonHawk]

The cable installer told me that there was. His reasoning (as I understood it) is that the cable company gets their signal the same way I would if I had an OTA antenna. They just rebroadcast that signal to me over the cable system. In the process the signal degrades a bit and some bits are lost.

The explanation I've heard (no idea if this is truth or b*llsh*t):

Cable operators have as much bandwidth as they have paid for in equipment and lines on the poles. The more channels (or other services) the cable operators can cram into their existing system, the more money they make off that existing system. So the cable operators have an incentive to compress their channels more, sacrificing a little signal quality to squeeze a few more channels out of their existing system.

OTA broadcasts, on the other hand, have a set amount of bandwidth per channel, and it's more-or-less fixed by FCC rule. They have no incentive to compress the signal more, since they can't sell you Internet service over the unused bandwidth. At the same time, OTA broadcasters are also trying to differentiate themselves from cable, so they have an incentive to make things look better if they can.

Thus, OTA HD often looks better than cable HD.

Or at least, that's what the men in black told me to say. ;)

[asjbcarter]

I'm just days away from a series 3 purchase and have yet to buy an HDTV. That's happening after Thanksgiving.

I've installed a $25 dollar radio shack antenna to pick up the local HD's. I'm using a borrowed Zenith HD receiver hooked up a standard Sony TV to test the signals. I'm happy to report they're coming in strong. The digital sample I'm seeing is 480i.

I've been a long time DirectTV customer with two series 2 (lifetime) DVRs picking off my favorite programs. When I switch video imputes between the the Direct TV and the OTA signal on the same channel, the picture quality is dramatically better on the FREE signal. The only thing I can say is I've been missing out on a quality picture. I hope the series 3 will maintain the OTA quality as advertised.

[MScottC]

...OTA broadcasts, on the other hand, have a set amount of bandwidth per channel, and it's more-or-less fixed by FCC rule. They have no incentive to compress the signal more, since they can't sell you Internet service over the unused bandwidth. At the same time, OTA broadcasters are also trying to differentiate themselves from cable, so they have an incentive to make things look better if they can.

Thus, OTA HD often looks better than cable HD.

Or at least, that's what the men in black told me to say. ;)

Most of your statement is correct. However, OTA station operators can choose to cram 1 or more Standard Def programs, and any other number of data streams in that same FCC allocated bandwidth, at the cost of reducing the the size of the datastream allocated to their primary HD signal. Those extra broadcast streams are a strong financial incentive to degrade the HD signal.

But I would concur that on the whole, OTA will typically look better than (tho perhaps not noticably) than Cable. Satellite on the other hand is way over compressed.

[ashu]

What MScottC said. PBS comonly splits their bandwidth between numerous subchannels. Locally, WETA (DC) splits into 26-1 (semi-OK-HD), 2-2,6 26-, 26-4 (all bad SD digitals) for an overall OK experience. And the signal strength where I am is weak ... so I use the cable-provided 726 (26-1 clone) instead.

Lets just say, that with optimal signal strength,

Cable HD quality of retransmiatted OTA locals <= OTA quality.

Cable can only get worse, and can't be any better than te source. In my area, it's essentially identical, for which I'm grateful to the current Adelphia framework, although I believe this will soon change as Comcast starts adding more HD channels! Double edged sword.

[Swisher]

Interesting topic. I've been using OTA and just installed my two cable cards (RCN - NY). While re-doing the guided set-up, I saw the option for choosing BOTH cable and OTA as inputs. I'm curious what advantage this would pose other than:

Having a back up if the cable went out <-- but would TiVo automatically switch?

Accessing channels OTA that aren't available on cable.

Any other advantages?

Can't see a difference in quality between the two, by the way...

[Jerry_K]

And that is exactly the crux of the matter. It all depends. Depends on local channel compressions of OTA, depends on local bandwidth sharing on the cable, and the amount of compression as well as the lossiness of the compress decompress of any. Have not seen cable in my area nor the HD on D*. I do like the HD OTA from my antenna "farm".

I have to agree with Ashu, 26 is a bit worse than 22 which I can pick up from Annapolis. Both are darned good tho. And the other locals are indistinguishable so far from DC and Baltimore.

And now the good news, we can discuss subtleties in the PQ from a wide variety of sources all of which are very good. Just some better than others. It is very very good when you have choices. And on other venues the folks from Dish are very pleased with the HD on their systems.

And the best news is that each day a few bucks drops off the price of the series 3. About $20 to $30 more and I pull the trigger.

[Bierboy]

So am I the only one who is thus far unimpressed with the quality of the TiVo Series 3's HD tuners?...n a word? Yes.

[HomieG]

Many cable headends now receive local stations via bit-stream directly from the TV station, not OTA. Cable companies can compress the locals more-so than I hear they actually do. I sure hope they don't get into the DirecTV mold of really squashing the HD locals.

I have local HD's available through cable and OTA. Slightly noticeable differences, most of which have been discussed above. Not enough for me to always view OTA (which is the slightly better, less-pixelated signal). YMMV.

[cwoody222]

Personally in my area, my OTA looks MUCH better on my S3 than cable on their HD DVR.

My S3's tuners are also MUCH better than my TV set's built-in one.