Why are HD broadcasts at 720
November 10, 2013 11:10 AM   Subscribe

(I could have some misconceptions regarding my question, so if so help me clear up my initial incorrect assertions.) It seems if most, if not all HD network broadcasts are 720p rather than the higher resolution 1080p. Why? Networks won't upgrade their cameras/transmission facilities? I spoke to my cable provider (Telus) and they assured me they could transmit higher resolution signals but the networks only provide them degraded quality feeds. Are there any networks that broadcast the higher quality signal?
posted by Keith Talent to Technology (13 answers total) 2 users marked this as a favorite
The original choice for HD broadcasters was between 720p and 1080i, and the ones that went with 720p generally preferred it over 1080i for content with fast motion like live sports coverage (which is, of course, a major seller of HD sets). That's the bedded-in spec, and the "degraded quality feed" line is guff.

The average size of a television sold in the US remains ~40in, and it's generally accepted that the difference between 720p and 1080p doesn't really kick in until around 50in; don't expect the networks to change their broadcast formats any time soon.
posted by holgate at 11:28 AM on November 10, 2013 [3 favorites]

It's also very expensive to upgrade the broadcast equipment, and while the parent networks might have that kind of money, they don't just give it to the local stations whose broadcasts the local cable companies retransmit. The financial burden is on the station owners.
posted by jason_steakums at 11:39 AM on November 10, 2013

the difference in bandwidth between 720p and 1080p is quite a bit unless you're using major compression. The difference in CPU power you need to decompress and smoothly play back 1080p is also quite a bit(unless it's hardware accelerated, but then you need a specific decoder and need to be transmitting the stream in that specific format).

1280x720 is 921,600 pixels, 1920x1080 is 2,073,600. thats 2.25x as much data.

The reason they use 1080i is that they get to "cheat" and only send a million pixels at a time. the hardware also only has to deal with encoding and decoding a million pixels at a time.

I'd be willing to bet that all this was set up when that was really pushing the limits of what the hardware could handle on the consumer end. i remember some early HD cableboxes having fans in them.

I also remember reading that one HD channel takes up the equivalent of like 4-5 normal channels in bandwidth on their network. So a 1080p channel would take up double a normal HD channel. Until everything is IPTV, FIOS style i just don't really see this happening.

When 4k becomes a huge thing, expect them to "cheat" on that and use interlacing 1080i style to save bandwidth. And possibly even only broadcast it at 44fps interlaced(so 24fps real)
posted by emptythought at 12:27 PM on November 10, 2013 [3 favorites]

The broadcasters would like to use as little bandwidth as they can get away with. 1080p recordings take up roughly twice as much space as 720p ones - meaning (overlooking compression for a moment) that they cost twice as much to send over a network, or take twice as long to stream. Yet the number of pixels only doubles from the lower resolution to the higher one. If viewers are watching on TVs that
1)Can upscale efficiently - pretty much a certainty.
2)Are being viewed from quite far away across a room and
3)Are not substantially bigger than the 40 something inch average - then they
1)Won't be able to tell the difference and
2) Will complain about extra costs or delays in getting to see what they want.

To make the sort of difference in resolution that people will notice you need at least 4 times as many pixels and a much bigger screen. 4K resolution - which offers 9 times as many pixels as 720p - offers the potential to do this - but - to be noticing a difference at 7 feet away you are going to need a display of at least 120 inches (see calculator). In short: nobody gets a good ROI going from 720p to 1080p; 4k - plus a great big TV - would mean you would notice the difference - but the standard is ahead of current broadcast technology.

The same calculator linked above tells you that if you are indeed watching a 40 inch TV then you are only going to notice the difference between 720p and 1080p at distances of about 7 feet or less.
posted by rongorongo at 12:28 PM on November 10, 2013

I want to reiterate that resolution does not necessarily equal "quality." As Holgate said, 720p has better temporal resolution than 1080i, and that's a winning proposition for sports broadcasters. Also, there's plenty that can be done to improve picture quality without going to 4K. Broadcast pictures are bandwidth-starved, and the result is just a ton of picture artifacts. I'd rather have a really exceptional 1080p (or even 720p, given my screen size) image rather than an overly compressed and thus artifact-ridden 4K image.
posted by Mothlight at 12:32 PM on November 10, 2013 [2 favorites]

FWIW, most cable providers are the source of "degraded quality feeds," in the sense that they apply compression algorithms to the network signals in order to free up bandwidth so they can provide you with more channels. If you use an over-the-air antenna to pick up your local networks, you will almost certainly get better picture quality than when viewing the same channel through your cable provider. The compression is most obvious when you're watching something with a lot of frame-to-frame changes in the image — for example a red carpet event with flash photos going off.
posted by stopgap at 1:18 PM on November 10, 2013 [1 favorite]

It seems if most, if not all HD network broadcasts are 720p rather than the higher resolution 1080p.

An over the air htdv channel is ~20Mb/s, which isn't enough for good-looking 1080p mpeg2.

It would probably look about as bad as your average "hdtv" channel on cable, where the companies commonly recompress channels down to half or a third of their bitrate so they can squeeze more channels that look like dogshit into the same space.
posted by ROU_Xenophobe at 1:55 PM on November 10, 2013 [1 favorite]

They have a choice between 720p and 1080i for broadcast. 1080p was not included in the spec for broadcast television at the time.
Its unlikely to updated anytime soon, but if it is, look for 4k/UHD and hevc/h.265 to be included. Going to be several years out for that though.
posted by TheAdamist at 1:58 PM on November 10, 2013

From a live production, network and delivery perspective, the 720p/1080i infrastructure investment is massive, with a decade or more left on its amortization table.

1080p is already an outdated standard. It was optimized only for Blu-Ray, which is dying fast. Digitizing 35mm amd theatrical production and projection is focused on 4K, and 4k is going to be the high end standard for home display in not too long.

So, expect a jump straight from 720p to 4k at various compression schemes, with the toe in the water in maybe 5 years as the oldest 720p mobile production truck-and-camera units come up for refresh, and the cable companies are feeling enough of a pinch from cord-cutters that they are willing to embrace something that their deadicated throughput will deliver much better than public internet services can.
posted by MattD at 5:33 PM on November 10, 2013 [3 favorites]

List of which networks use which standards. From 2010, but relevant and I'd be shocked if there had been any changes since. I would be curious to hear more about 1080p being optimized for BluRay. I would imagine the 1080p spec predates the BluRay spec by at least a few years, and BluRay was in competition with the HDDVD spec before it won the fight. Also not sure how it can be considered an outdated standard as there is no replacement standard with support all the way through the content distribution chain.
posted by mzurer at 6:31 PM on November 10, 2013

Many broadcasters where up and running with HD like around 10 years ago before 1080P was even available. There is no way they want to upgrade everything again that soon.
posted by Che boludo! at 6:55 PM on November 10, 2013

There's also a basic problem here, which is that sooner than anyone expected, broadcast television is approaching obsolescence. Future audiences will likely want internet streaming services exclusively. Cable remains entrenched for now, with ten times the viewership -- but everybody acknowledges it's a race against time (Netflix maintains "The goal is to become HBO faster than HBO can become us").

In essence, this particular hardware-tied distribution model is going the way of the dodo at some point in the next few decades or even years, and nobody is really sure how that's going to play out -- but it probably won't be through a major investment in upgrading broadcast standards.
posted by dhartung at 12:42 AM on November 11, 2013 [4 favorites]

There's also a basic problem here, which is that sooner than anyone expected, broadcast television is approaching obsolescence. Future audiences will likely want internet streaming services exclusively.

It's going to be an interesting time for local affiliate stations. There's really no reason for the networks to have them as middlemen in a streaming service, when they can geotarget ads and target set-top boxes, with the cable companies pulling the "local" stream over IP for retrans to non-cordcutters. Local broadcast news will likely have the rug pulled out from under it entirely if they haven't set themselves up as web-first services that can survive on ad revenue (with hugely stripped down studio equipment and personnel budgets) by then - and many, many markets won't support that for more than one local news site if any, and it may be the local newspaper's that wins out - because there's little reason for the networks to support them if they're not in big markets or on O&O stations. Likewise, local affiliate sales teams could be stripped down to almost nothing as advertising on network streams locally would be as easy as buying ads through their web ad networks.

It would also likely herald an absolute clusterfuck of FCC rulings encroaching further onto the internet and ISP attempts to get streaming content providers to pay to play, and a bubble popping in the broadcast tech sector. So that will be fun!

On the plus side, it might also create an environment in which local/regional independent web-based news organizations might thrive.
posted by jason_steakums at 9:28 AM on November 11, 2013

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