Sat vs. IPTV vs. Cable vs. OTA... compression/resolution? - AVS Forum
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post #1 of 21 Old 07-01-2014, 06:40 PM - Thread Starter
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Question Sat vs. IPTV vs. Cable vs. OTA... compression/resolution?

I've done some searching around, but can't find any recent information on the current state of TV picture quality. Does anyone have a resource to find out what the resolution, codec, and bitrate of the different services give you? It's been driving me nuts looking for it, and I would really like to know. Thanks!
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post #2 of 21 Old 07-02-2014, 04:43 AM
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A dirty secret that most broadcasters don't want you to know, plus compression can change on the time of day or type of signal being broadcast IE SD or HD.

Generally though OTA has the least amount of compression, Sat/Cab are a toss up, and IPTV is usually the worst...but as the saying goes "your mileage may vary" depending on location and/or stream.
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post #3 of 21 Old 07-02-2014, 08:26 AM - Thread Starter
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I've noticed and it's frustrating... It would be nice if they got in a battle over image quality, and actually said what they do. I'll definitely have an antenna, and then I'm trying to decide between Dish, DirecTV, Xfinity, and U-Verse. I had U-Verse early on and hated it due to serious macro blocking, and I've heard some places that Dish only goes up to 1440x1080 resolution. I'm sure things have probably changed since my experiences though. Thanks for the response... Too bad it doesn't help me a whole lot.
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post #4 of 21 Old 07-02-2014, 07:39 PM
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Quote:
Originally Posted by tfunk02 View Post
I've done some searching around, but can't find any recent information on the current state of TV picture quality. Does anyone have a resource to find out what the resolution, codec, and bitrate of the different services give you? It's been driving me nuts looking for it, and I would really like to know. Thanks!
in your area, u-verse is the absolute worst. actually any area u-verse services they are by far the worst provider. they are very limited by what they can transmit over their network.
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post #5 of 21 Old 07-04-2014, 05:30 PM
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Dish hasn't changed. It's still HD lite. But I honestly can't tell in most cases. DirecTV is very good. Cable may be just as good, but only someone in your area can tell you for sure. I've had them all and was satisfied the the PQ on all of them, Uverse being the worst, but still not terrible. I would not base my choice on that alone.

Bitrates are meaningless without knowing the compression scheme. And it will vary by channel. The best you can do is see it with your own eyes.
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post #6 of 21 Old 07-05-2014, 11:44 AM
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A few years ago I was talking to an engineer at our PBS station & he said Comcast did not add any compression. They send out what is given to them.
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post #7 of 21 Old 07-05-2014, 11:53 AM
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Quote:
Originally Posted by tfunk02 View Post
I've done some searching around, but can't find any recent information on the current state of TV picture quality. Does anyone have a resource to find out what the resolution, codec, and bitrate of the different services give you? It's been driving me nuts looking for it, and I would really like to know. Thanks!

Well, OTA'll give you the least compression, and it is usually 1080i or 720p, but some compress a lot to fit their 10 subchannels. OTA TV runs at around 21mb/s, but this is often split between subchannels. I don't know about cable or iptv except that they're almost always compressed. FIOS, on the other hand, doesn't add additional compression.
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post #8 of 21 Old 07-05-2014, 12:58 PM
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Originally Posted by mod50ack View Post
OTA TV runs at around 21mb/s,
Close. 19.39mbps to be exact.
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post #9 of 21 Old 07-05-2014, 01:44 PM
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Originally Posted by Mike99 View Post
A few years ago I was talking to an engineer at our PBS station & he said Comcast did not add any compression. They send out what is given to them.
AFAIK it used to be that way, when they just passed on the MPEG2 that was broadcast but now that most, including Comcast have switched to converting everything to MPEG4 all bets are off, they can do any amount of compression they wish and often do to cram more garbage channels down the pipe
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post #10 of 21 Old 07-05-2014, 01:48 PM
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Originally Posted by nyctveng View Post
Close. 19.39mbps to be exact.
Hence my "about." My memory is getting rusty!

Although this had proved to be enough for 3 (!) HD subchannels (one 1080i, two 720p), see WTRF-TV for an example.
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post #11 of 21 Old 07-06-2014, 02:48 AM
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Originally Posted by jjeff View Post
AFAIK it used to be that way, when they just passed on the MPEG2 that was broadcast but now that most, including Comcast have switched to converting everything to MPEG4 all bets are off, they can do any amount of compression they wish and often do to cram more garbage channels down the pipe
Thanks for the update. I dropped Comcast a few years ago so I'm not up to date on what they're doing. I'm using Dish which uses 1440x 1080 HD lite, but it does look good to me. The Dish DVR also has an OTA tuner module & I try to record the OTA channels via the OTA tuner vs a satellite tuner & there is a big difference in how much more HDD space an OTA recording takes up. It's been a while since I've done a same channel, same program comparison but the OTA took up about twice the space.
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post #12 of 21 Old 07-06-2014, 11:58 AM
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Quote:
Originally Posted by Mike99 View Post
Thanks for the update. I dropped Comcast a few years ago so I'm not up to date on what they're doing. I'm using Dish which uses 1440x 1080 HD lite, but it does look good to me. The Dish DVR also has an OTA tuner module & I try to record the OTA channels via the OTA tuner vs a satellite tuner & there is a big difference in how much more HDD space an OTA recording takes up. It's been a while since I've done a same channel, same program comparison but the OTA took up about twice the space.

OTA streams are always Mpeg-2, but satellite operators rencode them as h.264 which is about twice as efficient.
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post #13 of 21 Old 07-06-2014, 01:31 PM
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Originally Posted by spwace View Post
OTA streams are always Mpeg-2, but satellite operators rencode them as h.264 which is about twice as efficient.
I understand that. Dish also is only sending 1440x1080 vs 1920x1080. Would that be 1080i or would they convert that to 1080p? I'm presuming a 1280x720p signal would be sent as 720p.
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post #14 of 21 Old 07-06-2014, 04:43 PM
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Quote:
Originally Posted by Mike99 View Post
I understand that. Dish also is only sending 1440x1080 vs 1920x1080. Would that be 1080i or would they convert that to 1080p? I'm presuming a 1280x720p signal would be sent as 720p.
Don't think any US operators are using 1080p as a linear broadcast format, though some are using 1080/24p encoding for their VOD content. (Of course lots of US content is shot 1080p - but then broadcast within a 1080i signal)

(The UK OTA platform - which uses H264 not MPEG2 for HD broadcasts - is using adaptive i/p switching for their encoding - with the H264 encoders switching between 1080/25p and 1080/50i dynamically based on content to improve compression efficiency)

It looks increasingly likely that 1080/50p and 1080/59.94p will not be used as broadcast delivery formats, with 2160/50p or 2160/59.94p (aka 4K UHD TV) being the next standard format (unless a double framerate is chosen - though as a first step this looks less likely) HEVC/H265 is likely to be the compression scheme used (The BBC are broadcasting 35-39Mbs 2160/59.94p HEVC/H265 World Cup matches from the Maracana stadium in Rio using the UK's HD standard OTA modulation scheme of DVB-T2, which delivers just over 40Mbs per mux)

**EDIT : Though no sooner than I type that than I read the EBU (European Broadcasting Union - the association of European Broadcasters) report that suggests that rather than 4K at existing bit depth and frame rate, an enhanced 1080p system may be preferable instead as a first step to UHDTV : https://tech.ebu.ch/docs/techreports/tr028.pdf (Paraphrasing "better pixels may be better than more pixels" ) ***

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post #15 of 21 Old 07-07-2014, 08:14 AM
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Originally Posted by sneals2000 View Post
**EDIT : Though no sooner than I type that than I read the EBU (European Broadcasting Union - the association of European Broadcasters) report that suggests that rather than 4K at existing bit depth and frame rate, an enhanced 1080p system may be preferable instead as a first step to UHDTV : https://tech.ebu.ch/docs/techreports/tr028.pdf (Paraphrasing "better pixels may be better than more pixels" ) ***
Though I think for "Phase 1" of UHDTV they're still saying 3840x2160 without higher frame rates (so only 50/60 fps) and without other enhancements will be the normal standard, and Phase 2 will be 3840x2160 with higher fps and better colour, and that an enhanced 1080p standard could be appealing for some broadcasters and should also be developed as a broadcasting standard. So it looks like it could be an additional option for broadcasters as well as the 3840x2160 standards (phase 1 and the better phase 2).

It might be like now where we have 1080i channels and also 576i channels. So in future we could have 2160p50 channels and also at some point 1080p50 channels (and a couple of years after phase 1 there's 2160p100 channels or better? with the better colours).

Last edited by Joe Bloggs; 07-07-2014 at 08:21 AM.
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post #16 of 21 Old 07-07-2014, 02:57 PM
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Originally Posted by Joe Bloggs View Post
Though I think for "Phase 1" of UHDTV they're still saying 3840x2160 without higher frame rates (so only 50/60 fps) and without other enhancements will be the normal standard, and Phase 2 will be 3840x2160 with higher fps and better colour, and that an enhanced 1080p standard could be appealing for some broadcasters and should also be developed as a broadcasting standard. So it looks like it could be an additional option for broadcasters as well as the 3840x2160 standards (phase 1 and the better phase 2).

It might be like now where we have 1080i channels and also 576i channels. So in future we could have 2160p50 channels and also at some point 1080p50 channels (and a couple of years after phase 1 there's 2160p100 channels or better? with the better colours).
I think there is some disagreement between the DVB and EBU camps on this. DVB are pushing for UHD Phase 1 to be 2160/50p or 60p with a potential shift from 8 to 10 bit - but not higher frame rates or massively wider colour gamut. The EBU (though individual members may not agree - just as many didn't agree with the EBU when it came to them promoting 720/50p rather than 1080/50i) appear to want 1080p but with higher frame rates, wider colour gamuts to also be considered. I can see the production and technical reasons behind this - but 4K vs 2K is a much easier "sell" for the marketers and pay-TV broadcasters...
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post #17 of 21 Old 07-07-2014, 03:11 PM
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The Xfinity premium channels (HBO/Showtime etc) usually look pretty darn good, but it is a toss up on the rest of the service. The two best I've services I've ever seen were OTA and Surewest FTTH that was essentially IPTV.
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post #18 of 21 Old 07-29-2014, 09:14 AM - Thread Starter
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Definitely wish they would get into a PQ battle, but I guess 99% of the people out there would never know/understand. I have DirecTV, but since they haven't picked up the SEC Network I'm looking at Dish, Xfinity, and U-Verse. My U-Verse can be bonded and go to 45Mbps... but I don't really know if that helps PQ when I've always hated IPTV, I hate that Dish is HD lite, and Xfinity is Comcast. Basically, I have to choose the lesser evil. It sucks that there is no perfect option for me.
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post #19 of 21 Old 08-06-2014, 09:48 AM
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The discussion so far centers around the final delivery link, but you need to look at how the content was transmitted all the way from the content provider out to the "edge network" (cable, OTA, Sat)

For the most part, the video stream is packetized, and shoved into the "network pipes" so as not to waste any time slots in the TDM transmission stream. Satellite broadcasters were the first to use "statistical multiplexing" to get 100% utilization of the uplink bandwidth, but cable companies have been adding "stat-mux" to hybrid fiber coax distribution systems.

This is a technique that "looks ahead" at the data that needs to be packed into a TDM stream (a lambda in fiber optic systems). The goal is to not waste any time slots with "no data". The stat-mux decides who's packet gets to go to the head of the queue and get sent.

This can create high latency, out of order packets and other network conditions that result in macroblocking in your tv image.

If you were one of the first 1,000 Directv customers to "beta" their 2 HD channels, you were a guinea pig for testing new stat-mux algorithms for HD. It's come a long way in 15 years, and still improving.

Bottom line is that the bit rate is not the only determining factor in video quality, since a content stream does not get guaranteed bandwidth end to end in the network(s).

All of this "magic" happens at "Layer 2" in the network. Whether Layer 1, the physical layer, is cable, DSL/VDSL, Fiber, or Satellite RF, is not as important as Layer 2, where the packet stream is managed.

All of the CSP's are converging on using the same set of signal processing techniques at L2, so I expect to see smaller and smaller differences between providers.
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post #20 of 21 Old 08-10-2014, 11:35 AM
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As far as the OP title's "resolution," recently I tried measuring the resolvable or effective resolution from two sources directly on my 1090p plasma screen. Used the luma multiburst patterns from the 1st-edition S-M calibration disc with these results for two 4k-DI-Blu-ray scene details and one 1080i Golf Channel scene. Basically it's just comparing on-screen widths of scene details with frequency burst widths, converting the frequencies to lines/picture height (so-called TV lines) then lines per source aspect ratio. Haven't tried it, but this should also be possible with downloaded multibursts from dr1394'a website: www.w6rz.net or elsewhere. I'd want to check computer processing--perhaps measuring the 1920-line bursts per inch, then multiplying across my screen width. -- John
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post #21 of 21 Old 08-11-2014, 09:49 AM
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agree with you,All of this "magic" happens at "Layer 2" in the network. Whether Layer 1, the physical layer, is cable, DSL/VDSL, Fiber, or Satellite RF, is not as important as Layer 2, where the packet stream is[IMG]http://*******/xp1ekA[/IMG] managed.
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