AC-4 Audio?

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TBR
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Re: AC-4 Audio?

Post by TBR »

hdhruser wrote: Tue May 04, 2021 9:23 pm I don't know if this will help you at all, but it looks somewhat similar to what you are trying to do. It is decoding the audio in real time from a satellite TV channel from a big old C-band satellite dish, that sends six channels of audio (5.1 format) in three discrete 2-channel streams. You should not need the complex filter but the rest might be useful. I just thought perhaps looking at the ffmpeg command they use might help you in some way, though since you are not using Tvheadend you'll probably have to make some adjustments.

https://freetoairamerica.wordpress.com/ ... -nameless/
Thanks for the tip, but the problem I had (before I ran out of time to work on it) was streaming between devices over my LAN. I have richardpl's FFmpeg transcoding the AC-4 audio to AC-3 and passing through the H265 video, but I could not get VLC to play the stream on a separate device despite trying a variety of containers (such as mp4) and network commands. Since then I've had to deal with 5G trashing my television signals, building multiple computers, the chores of spring, rebuilding my car's suspension, etc., etc., etc., so I've quite forgotten most of the details. Hazards of old age :D

hdhruser
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Re: AC-4 Audio?

Post by hdhruser »

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hdhruser
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Re: AC-4 Audio?

Post by hdhruser »

TBR wrote: Wed May 05, 2021 7:30 am
hdhruser wrote: Tue May 04, 2021 9:23 pm I don't know if this will help you at all, but it looks somewhat similar to what you are trying to do. It is decoding the audio in real time from a satellite TV channel from a big old C-band satellite dish, that sends six channels of audio (5.1 format) in three discrete 2-channel streams. You should not need the complex filter but the rest might be useful. I just thought perhaps looking at the ffmpeg command they use might help you in some way, though since you are not using Tvheadend you'll probably have to make some adjustments.

https://freetoairamerica.wordpress.com/ ... -nameless/
Thanks for the tip, but the problem I had (before I ran out of time to work on it) was streaming between devices over my LAN. I have richardpl's FFmpeg transcoding the AC-4 audio to AC-3 and passing through the H265 video, but I could not get VLC to play the stream on a separate device despite trying a variety of containers (such as mp4) and network commands. Since then I've had to deal with 5G trashing my television signals, building multiple computers, the chores of spring, rebuilding my car's suspension, etc., etc., etc., so I've quite forgotten most of the details. Hazards of old age :D
Just out of curiosity, did you ever try recording a stream, and if so was VLC able to play the recording? It just seems to me that if you can record the signal and it will then play back on the device that recorded it, it should play on other devices as well. However I do know that H.265 is a bit much for some systems. Part of the problem is that on many systems the GPU's will decode H.264 but not H.265, so H.265 gets sent to the CPU for decoding and some CPU's just can't handle it (for example there is no way you will play H.265 on a Raspberry Pi unless something has changed recently). So maybe your separate system is just struggling with a signal that is too much for it to handle? Unfortunately I think that is only going to get much worse if the stations ever start broadcasting in 4K.

I hear you about the hazards of old age, people don't understand when you can't remember how to do something that you just did a couple weeks or a couple months ago. Sadly, the aging process can be brutal on the memory!

ferrellsl
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Re: AC-4 Audio?

Post by ferrellsl »

(;-)
Last edited by ferrellsl on Wed May 05, 2021 9:42 pm, edited 1 time in total.

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Re: AC-4 Audio?

Post by ferrellsl »

(;-)
Last edited by ferrellsl on Wed May 05, 2021 9:42 pm, edited 1 time in total.

hdhruser
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Re: AC-4 Audio?

Post by hdhruser »

ferrellsl wrote: Tue May 04, 2021 9:56 pm
hdhruser wrote: Tue May 04, 2021 9:23 pm
The one thing I would really like to see is a static build of richardpl's ffmpeg for LINUX, similar to the ones at https://johnvansickle.com/ffmpeg/ for the master branch. Not everyone uses Windows, and at the same time not everyone that uses Linux (particularly as a home theatre system) is a programmer or is capable of compiling from source code. So a static build of richardpl's ffmpeg for Linux would be very helpful.


There's a very good reason that you don't see pre-compiled binaries for ffmpeg and other apps on the net for download and usage under Linux. That reason is the sheer number of Linux distros in use by the general public. For example, just because you've successfully compiled ffmpeg (or any other package for that matter) on your Linux/CentOS system doesn't mean that you can simply copy the binaries over to your Linux/Ubuntu 20 LTS machine (or any other Linux box) and expect those binaries to run. There are as many Linux distros out there as there are colors in the rainbow and Linux binaries are not universal. So, if you insist on using Linux of any flavor, it's expected that you will either use the software repositories for YOUR version of Linux to install apps for your particular distro or build the apps you need from source. That's what attracts so many power users to Linux in the first place. If you want ubiquitous binaries, then you need to stick to the commercial operating systems such as MacOS and Windows, plain and simple. It would rather ridiculous to expect someone to compile and maintain ffmpeg binaries for every version of Linux under the sun as there are literally thousands of versions/distros of Linux.

You're also making things appear to be way too difficult for an average Linux user. Building the binaries from richarpl's source tree is as simple as typing in the following command in a terminal window where you've downloaded his code: ./configure & make

If you're not able to unzip some files, open a terminal window and type: ./configure & make, then you probably shouldn't be using Linux in the first place.
Since posts that followed up on this one were removed by the moderator, and since I know you already read my response that got removed, I just want to point out the one factual error in your post: It is not true that "you don't see pre-compiled binaries for ffmpeg and other apps on the net for download and usage under Linux." In fact you see exactly those things - I provided the link for the static build of ffmpeg provided by John Van Sickle, and also there are several AppImages of various pieces of software that will run on various Linux distros (I had given an example but since I am not sure exactly what got my other post removed I won't give it again). It is not necessary that such builds run on every Linux distro that exists, just the most popular ones that would typically be used by regular users, by which I mean those who are not programmers or developers and that have no interest in software development. I assume that many of those types of users are current or potential customers for HDHR ATSC 3 devices, and would like to be able to use those devices to the fullest potential.

I also strongly disagree with your assertion that "If you want ubiquitous binaries, then you need to stick to the commercial operating systems such as MacOS and Windows, plain and simple." That may have been true a couple decades ago but not today, and with Snaps and Flatpacks becoming more common I think that will become even less true as time passes.

TBR
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Re: AC-4 Audio?

Post by TBR »

hdhruser wrote: Wed May 05, 2021 11:07 am Just out of curiosity, did you ever try recording a stream, and if so was VLC able to play the recording? It just seems to me that if you can record the signal and it will then play back on the device that recorded it, it should play on other devices as well. However I do know that H.265 is a bit much for some systems. Part of the problem is that on many systems the GPU's will decode H.264 but not H.265, so H.265 gets sent to the CPU for decoding and some CPU's just can't handle it (for example there is no way you will play H.265 on a Raspberry Pi unless something has changed recently). So maybe your separate system is just struggling with a signal that is too much for it to handle? Unfortunately I think that is only going to get much worse if the stations ever start broadcasting in 4K.
Actually, no, although that would have been a way to test at least the transcoding portion.

VLC seems to play H.265 video just fine on all my devices (Windows, Ubuntu, and Android). But VLC lacks an AC-4 decoder, so there's no sound when playing an ATSC 3.0 stream. I hoped that transcoding the audio would allow VLC to play a modified stream on a device without AC-4 decoding capability, such as an Android TV Box.

As far as playing H.265 on a Raspberry Pi... I recently put a Pi 4B online as my NAS and media server. I'm not willing to experiment at the moment, but there is a Raspbian VLC and it would be fun to try. There still wouldn't be audio from HEVC channels, but VLC seems to be much more efficient at playing H.265 than many other programs such as ffplay.

ebo
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Re: AC-4 Audio?

Post by ebo »

According to the specifications the Pi 4B can decode (but not encode) H.265 in hardware. So Raspbian VLC, Kodi and any other video player should be able to pkay it. No word on decoding or transcoding AC-4 yet but the 4B should be powerful enough to do it in software once someone writes it.

IRJ
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Re: AC-4 Audio?

Post by IRJ »

I have an early release Connect 4K Quattro attached to a Servio and ATSC 3 OTA is set to begin broadcasting middle of June in my area.
I hear that some early release of the tuners are not compatible with AC-4
Question: How do I check I have an updated unit. Is it software or hardware?
Thanks

signcarver
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Re: AC-4 Audio?

Post by signcarver »

The tuners have nothing to do with AC4 and have always supported such when tuned to an ATSC 3.0 channel as that is what the spec states it would be. It is the client (rendering) devices that may have issue with AC4 not the tuners. Typically the tuner would be completely agnostic to what codecs are in use but there was an issue of a station using AAC and because of the ATSC 3 stream needing to be put into a "standard" ts stream it didn't add that "track" for that "one" station that did so and a newer firmware was needed.

IRJ
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Re: AC-4 Audio?

Post by IRJ »

signcarver,

Let me make sure I understand.

It's the vehicle that I use after my 4K Connect tuners and after my Servio DVR which handles the audio conversion?
I am using the latest Nvidia Shield (fully updated) to project the Video and Audio. I presume this is fully capable.

While a Roku is iffy and what of the latest Chromecast?

I should add that I use a Sony STR1080 AVR
Last edited by IRJ on Fri May 14, 2021 7:24 am, edited 1 time in total.

signcarver
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Re: AC-4 Audio?

Post by signcarver »

Yes, it is the client device/software that is responsible for both audio and video unless you have something in between that is doing transcoding before hand which SD's software/hardware/dvr does not (they had the extend tuner that did for what it tuned but with that you wouldn't need to worry about ATSC 3.0, HEVC and AC4 as it as ATSC/clear qam only)

I don't know the latest on the shield (I loaned my old one to my parents when I needed to be sure they had a good streamer during the pandmeic so haven't been able to test it with ATSC3). Some models didn't support such but SD's apps I think have been updated to support it on "any" shield but I am not 100% certain on that and there may be other requirements... older (pre 2019) shields may still require connection to something that can handle AC4 like an lg tv from 2020 or later (generally the only tvs I see stating AC4) or AVR/sound bar... I would make sure any AVR (or whatever you hook the client device to) supports Atmos to be a bit more safe but technically Atmos isn't AC4 but in theory any thing that licensed Atmos most likely has a license for AC4 as my understanding there isn't any additional charge. For a while Channels was the "only" thing that seemed to work on any shield for AC4 consistently. I believe you won't have any problem with the sony provided it is connected to it and not via ARC/eARC (many TVs may have trouble passing AC4 and/or may require eARC to pass it or "Atmos" even if the bit rates are low enough).

In the case of my chromecast (w/ google tv), I had to hook it up to my soundbar rather than to the TV and I haven't tried not with the sound bar on the TV I had trouble with since November (prior to November I didn't have a soundbar in that room)... my other chromecasts(w/ google tv) are on things that would support ac4 anyway and never had issue.

The lastest roku's that support AC4 fixed the limitation of it not being in a ts with their latest update as previously roku's only supported AC4 in hls streams or certain file formats, not TS.

IRJ
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Re: AC-4 Audio?

Post by IRJ »

Thanks for that comprehensive reply.

Who would have thought that receiving Audio would be such an issue for ATSC3. Well not me for one. LOL.
But then again I should have been fearful as I find that the many streaming platforms need me to manually adjust my AVR's sound fields to get decent Audio reproduction. Gone on the days when one simply switched a TV and and watched and listened.

RonRN18
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Re: AC-4 Audio?

Post by RonRN18 »

I run my Plex Media Server as a jail on a TrueNAS server (FreeBSD). I realize that people have mentioned that FFMPEG that comes built-in with PMS is not capable of decoding AC-4 audio. On the same TrueNAS server, I created another jail and built an experimental FFMPEG with AC-4 support. I have only been able to find 30-second test files to try to convert, so I don't know how well it is for anything longer. I am not sure what would happen if I were to try to build the same FFMPEG in the same jail as PMS or install PMS in the same jail as a built FFMPEG. Has anyone messed with this yet in Plex in a FreeBSD environment? The first ATSC 3.0 lighthouse station in our market is supposed to go on the air in about a week (June 1st) so I plan to do some messing around soon but I'd like to hear what others have discovered. I'm a tinkerer as opposed to an expert coder, so much of what I do is flying by the seat of my pants.

RonRN18
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Re: AC-4 Audio?

Post by RonRN18 »

signcarver wrote: Thu May 13, 2021 5:31 pm The lastest roku's that support AC4 fixed the limitation of it not being in a ts with their latest update as previously roku's only supported AC4 in hls streams or certain file formats, not TS.
I am a little curious about your comment. I'll soon have ATSC 3.0, as our first station is supposed to go live on June 1st and all of my televisions either have Roku built-in or have a Roku attached. As to built-in, I have a 75" TCL and two 55" Hisense TVs with Roku built-in. I then have a 70" Vizio with the latest Roku Ultra and a 46" Samsung 1080p with an Ultra that is a couple years old. I know that the newest Roku Ultra attached to my Vizio and my TCL are running the latest Roku OS 10.0.0 but I have not checked the others to see if 10.0.0 was available last (it has been a few weeks since I've had a chance to play with the Hisense TVs to see if 10.0.0 had come out on them yet.) I do know that in the settings of the Hisense, there are settings for AC-4 audio, so in one fashion or another, it should have a decoder built-in. Given this, what is the likelihood that I'll have audio when watching live or recorded content with Plex on ATSC 3.0? Are most stations converting audio to AC4 that have gone ATSC 3.0?

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