Keeping this thread alive… AC-4 is a huge issue for everyone.
Adding to the “don’t let this close” chorus.
For me personally (in Dallas) this didn’t end up being a huge deal as our local NBC channel didn’t get 4K setup in time for the Olympics. But considering our local Fox is already setup it’ll become more an issue as the NFL season starts.
Seems to me like this is an opportunity for Plex to have a cool feature not a lot of other systems have. 10-second Superbowl ad: “You could have been watching this in 4K, Plex” 
@Tedg - Plex ac4 support aside, I would recommend strongly tempering your expectations of actual 4k broadcasts anytime in the relatively near future given the realities of the limited bandwidth available as they are now cramming 1.0 and 3.0 into the same amount they had previously and won’t be able to retire 1.0 for another ~4 years. Also, none of the major networks are capturing and distributing video in 4k (no fully 4k workflow). So if you do happen to be in a market that does something to get 4k video broadcast for an event, the reality is that it probably was capture in 1080, managed and distributed in 1080, and didn’t become 4k until it was upscaled prior to broadcast (something that your TV could do on its own with a 1080p signal).
Considering it is a different RF signal than the ATSC 1.0 stream, they’re not competing with each other for bandwidth. And, frankly, the ATSC 1.0 20Mbps is more than enough to send HD and 4K on modern encoders.
Also, much of the games is being captured with 4K cameras and being given to NBC in 4K. NBC has said they’ll be sending many events in 4K to local broadcasters. NBC Universal to show the Olympics in 4K HDR and Dolby Atmos
Anything is possible without knowing each broadcaster’s individual workflows. But considering we’re getting to the point where the on-site source materials are 4K, I think there’s reason to be excited.
The RF signal being different doesn’t have to do with the FCC frequency bandwidth that the stations have to use for those different signals in any given market. What the different stations have done in these markets is work together to move stations around and make other adjustments to allow for the additional atsc 3.0 stations, usually all broadcasting from the same lighthouse. The atsc 1.0 19.4mbps (or the atsc 3.0 ~26mbps) is not bandwidth in terms of what wavelengths that have access to. It is also never used for a single channel and likely never will be as making money requires carrying the subchannels. Higher resolution does not make them any more money.
As for the sports broadcasters, there may be some that have some 4k cameras they have started to use but note that there is still no live 4k workflow to the local markets.
If you want to know more, there are some folks on the HDHR forums who work in the industry that have commented on this topic and why most everyone shouldn’t expect 4k, especially no end-to-end 4k over broadcast anytime soon. I am just repeating what I learned from them and others, I don’t have any specific insider knowledge myself.
You’ve got a couple of things confused there. The FCC allocates 6MHz channels for specific purposes, which would be for Digital TV broadcast. In most areas there are way more of these channels than what is used, mostly to avoid overlap between cities in places like the East Coast.
On each 6MHz channel the broadcaster can run either ATSC 1.0 (8VSB) or ATSC 3.0 (OFDM) modulation which results in a certain amount of digital bandwidth. In the case of ATSC 1.0 that’s roughly 20 Mbps, where in the case of ATSC 3.0 it is configurable, but can go up to 57 Mbps.
Each of these digital streams can have multiple video/audio/data streams that can be associated with “channel numbers” on a user’s TV set. They can be either main video/audio feeds or they can be subchannels. So 8.1 and 10.1 could be in the same stream, or just 8.1, 8.2 and 8.3.
The local operators can have multiple RF channels, but that is expensive, so most of them are working together and putting multiple channels on a single RF feed. There’s no technical requirement there, just something they’ve chosen to do. So while the ATSC 3.0 standard allows for more bandwidth per RF channel, it doesn’t exactly mean that each operator would have more if they have chosen to share with other operators (lighthouse). I imagine that, long term, we’ll see operators share channels on their ATSC 3.0 feeds, and then move to share on their ATSC 1.0 feeds as they deprecate them.
While each station could have a full 4K workflow, and would like to for sure, they don’t need the full work flow to start broadcasting 4K content. What I see on my Fox feed in Dallas is that the bitrates/format change when broadcasting football games. I imagine that’s because they’re passing along the national feed in that case, instead of processing it locally. This means they can’t do things like live break-ins and put their logo overlay in, but those aren’t requirements for broadcasting 4K content.
At the end of the day it all depends on demand. If more people demand and get excited about 4K content, operators will get excited about providing it. I wrote my local NBC channel about how I was disappointed they weren’t broadcasting the Olympics in 4K. Does that mean they’ll change tomorrow? Nope. But hopefully it will show them there is some demand for the better content.
Agreed here that AC-4 is something that really is needed, I’m one of those that looks to benefit from some of the multipathing rejection in ATSC 3.0 completely aside from the 4K aspect.
That said, to the discussion of the Olympics 4K broadcasts, NBC is pulling the raw 1080 feed from OBS and iOS sling it prior to broadcast because, as has been pointed out, they don’t have a fully 4K compatible workflow yet. Now it does look better than the normal cable feed (we grabbed YTTV for the games since so little is actually on the local broadcast station). I’m guessing this is partly due to a higher quality raw feed along with better quality upscaling than what most TVs can do simply due to more processing available. My biggest complaint is the colors look a lot more muted on the 4K feed likely due to poor HDR mastering either from OBS or from NBC.
It looks like I am getting ATSC 3.0 next week in my area. Does the sound still not work when watching through plex?
Sorry, Ron - Unfortunately, Plex doesn’t support AC-4 yet. The only way I have been able to get audio on NG channels is to play them through the HDHomerun app.
I have Apple TV 4K and HDHomeRun Flex 4K and the ATSC 3.0 channels from Indianapolis work fine, picture and sound using the HDHomeRun App in the Apple TV.
Hey, @ClarkCabin - The HDHomeRun App works fine with ATSC 3.0 channels and AC-4 audio. That’s been known for a while, and actually a sore point with a lot of folks like me who dropped (or, wasted) money on the HDHomeRun 4K tuner Kickstarter program. I (and many others) are hoping that Plex will someday support AC-4 audio when it get incorporated into the official ffmpeg libraries.
SilconDust was intentionally deceptive about offering the HDHR 4K tuner before it was ready to go to market. SD knew that AC-4 audio was incorporated into the ATSC 3.0 standard, and almost no hardware or software existed (and, for the most part - still doesn’t exist) to decode AC-4 when they started their KS program.
How many participants do you think SD would have had for their Kickstarter program if they had a little star next to the tuner description that said, “Requires an AC-4 audio decoding receiver, or you must use the HDHomeRun application to play ATSC 3.0 audio”?
I know I never would have given SD a tarnished penny until I knew that I had a way to decode AC-4 audio through my existing home audio receiver. There’s no way that I will be replacing my audio receiver just to play AC-4 audio, either. It’s very hard to find an inexpensive multichannel receiver (or tuner/preamp) that has line level outputs these days.
I bet SD would have had somewhere between 1/2 to 3/4 of their Kickstarter participants drop out if the limitation of AC-4 audio decoding was common knowledge before they shipped the units out.
If you look at the date when I started this Plex thread, it was a day or two after the first shipment of HDHR 4K units started to arrive on US doorsteps. We’ve been waiting that long for a Plex solution. And, I’ve been waiting that long to record and play back the ATSC 3.0 shows that are broadcast in my city.
Still waiting for AC-4 support.
Came here with the same problem. Good to see the cause is sorted out. Would love to get a fix, even if I’m forced to pay a few $$ for a codec license.
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See for more info: ATSC3.0 Broadcast and AC-4 Sound - #63 by gbooker02
Came here to see if Plex has obtained permission from Dolby to use the AC4 audio codec. I have been able to get the ATSC 3.0 video and closed caption streams fine from my HDhomerun5_atsc3 tuner but only able to get audio from the HDHomeRun app for Win10. It appears to have the needed codec either bundled with it or was installed with another audio application. Since my Plex media server runs under Linux this doesn’t help with my DVR recordings. I have started writing my local stations that are dual broadcasting to inform them I don’t plan on upgrading my tv for another 3 years and expect them to honor FCC’s requirement to dual broadcast for 5 years.
I do want to say that comparing the ATSC 1.0 and ATSC 3.0 video from my tuner - I can’t see any improvement with my existing TVs.
You’re not likely to see any video improvement for a while.
I haven’t seen where any US national broadcasters are putting out real 4k content at this time (NBC had the opportunity for the Olympics, but didn’t use it), and I haven’t seen any 4k from our local broadcasters, either.
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You don’t see an improvement because it is the same source and resolution, just encoded differently. The change is about enabling same or better quality at lower bitrates so they can get more channels. One day we may get 4k but it is far in the future and will likely start as just pre-upscaled 1080 feed.
AC4 concerns don’t matter in regards to whether you are going to upgrade your TV or not as you can play it fine on the TV either using HDHR app on it if has one or any of the many media device you can run it on (Roku, Apple TV, etc). And ac4 DVR playback is already available via HDHR’s software for DVR if you want that or Channels or Emby. Plex doesn’t yet but it is in the process and the atsc 3 world is not dependent on this one program (though it will also be working fine with ac4 soon enough). Every program will handle AC4 years before 1.0 goes away and years before there is any value in recording the 3.0 signal over the 1.0 version (as there is none now, bar someone with unique reception issues that 3.0 helps)
As for writing the stations, I’m not sure why you are bothering to do that. The FCC rules are what they are and they can’t just decide to stop broadcasting 1.0 next year because they feel like it (nor would they care what one viewer’s personal upgrade cycle is).
Yes, they must run ATSC 1.0 and ATSC 3.0 side by side for at least 5 years. Some markets have channels that can theoretically turn off their ATSC 1.0 signal in 2025 (a little under 4 years from now). At this point I’m not too worried about it (my area can turn off 1.0 in October 2025) and I’m fine with my Quatro HDHomeRun (1.0 only), but at the same time, I won’t buy a new TV without an ATSC 3.0 tuner built in…since I keep TV’s for at least 10 years.
Do you really care if it has a TV has (any) tuner built in? A TV tuner doesn’t allow you to record and requires the antenna signal to reach it (which may mean dealing with splitters, amps, placement issues). With HDHR or other similar ATSC tuner, you get 4+ tuners, that you can use for any display in the house, DVR capability, much more flexible placement, cheaper replacement should there be a future tuner that does something amazing that you want, etc.
Personally I do not care about anything in a TV besides its, inputs, display quality and calibration capabilities. No tuner, no soon to be outdated built in ‘Smart’ features, or anything else. All a TV needs to be is a computer monitor essentially. Though sadly we won’t get away from their built in App OS as that is how many are making much if not most of their money. Vizio’s Profit On Ads, Subscriptions, and Data Is Double The Money It Makes Selling TVs - Slashdot
Yes, have you seen how slow the channel changes with a network tuner? Plex is one of the slowest to change channels (even when it is direct playing the feed from the HDHomeRun) and the Android TV “Live Channels” is one of the fastest, but they are all still slower than my built in tuner. Plus I already have the antenna run via coax to all the rooms in the house that have coax, so no extra work. I’m close enough to the towers that a simple 4 way distribution amp (ironically right next to the the HDHomeRun is good enough). Always good to have a few extra tuners in the house as that way you don’t have a single point of failure – even if you can’t record with them.
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