AC3 passthrough

Ashan Sol

Hello all,

I have an HTPC built using Fedora 25 and TvHeadend 4.1. I'm running Kodi Krypton 17.1. My A/V receiver is a Marantz SR-6009, capable of decoding pretty much anything via HDMI (A52, DTS, DTS-HD, etc).

In local Kodi playback (movies and whatnot), the passthrough works flawlessly - AC3, DTS, etc. However, live ATSC streams do not pass A52/AC3 audio. I've tried changing the default streaming profile via hts.pvr config without effect (in fact, the addon doesn't acknowledge any profile except default).

So my question is, when using the HTSP stream protocol with Kodi, does it pass AC3 by default, or does it pass separate PCM channels? For live TV streams, my AVR shows multi-channel PCM input, but I'm not sure if that's because TvHeadend is "decoding" the AC3 or because the hts.pvr addon is.

To be perfectly honest, I'm not entirely sure the OTA streamsactually include 5.1 channels of audio data, so when I'm not hearing anything from the rear channels it may be the programming.

Thanks,
Ashan

Saen Acro

It's Kodi setting to set passthrough,
wrongly configured Kodi do not pass stream.

Few versions ago there is a bug in kodi parser hope is fixed.

For more info ask in kodi forum.

Robert Cameron

IIRC, audio pass through for Live TV was removed in 17.x. It only affects Live TV streams played through the PVR manager, but there was some odd error or bug that was quite difficult to track and isolate (and because of some other reasons related to the restructuring of how Live TV works in Kodi) so for now it's gone. It may be enabled at a later date.

Sean Micklem

You gotta be kidding.

How many years will I have to keep running Isengard before I can get a new version of Kodi that actually works? Seems like every new version they break something related to PVR functionality.

OTA TV shows very much do have 5.1 audio, at least the ones created in the last several years do. It is dolby-encoded and while not every channel has it, most do, especially in major markets. And the only way to send it to the receiver is using passthrough audio. I also find that at least in Isengard, I have to make sure Kodi is using ALSA and not PulseAudio (of course that only affects those using Linux as the operating system).

Now, when you say "It only affects Live TV streams played through the PVR manager", are you saying that if you start recording a program and then wait a few seconds and start playing the recording the passthrough audio would work? If so, I can live with that for now, because I very rarely watch "live" TV anyway. But if you mean that anything that originally came from a Live TV source, whether recorded or not, cannot use passthrough audio anymore then that means that Isengard will stay on my HTPC for now.

Sometimes I think the Kodi developers get some perverse joy out of tormenting PVR users. :(

To the OP: If by chance you are running Linux (such as Ubuntu or Mint) as your OS, try starting it like this from the command line:

pasuspender

AE_SINK=ALSA nice -20 kodi --standalone &

(the "nice -20" isn't strictly necessary but it gives Kodi top precedence, which can help avoid some motion jerkiness on low-powered systems).

Then make sure you configure Kodi's audio settings to use ALSA. If Robert is wrong about audio passthrough being removed, or if it doesn't affect recordings, then this might solve your issues. You can put those two lines in a bash script and run that when you wish to start Kodi. Might be worth a try.
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Robert Cameron

Here's a forum post from Kodi's forums about it: http://forum.kodi.tv/showthread.php?tid=307528

In short, it is only for Live TV. Recordings are not affected. (This is partly because recordings are played like regular movies/media, but Live TV uses a different paradigm.)

Sean Micklem

Why I can't understand is why they felt they had to change it. It worked fine in Isengard.

Seriously, at some point I may wind up going back to MythTV, not because I care for their backend in any way, but because they have the only frontend I have seen that actually works the way a frontend should work. I have been thinking for quite some time now that I truly wish there was some way to use MythTV's frontend with Tvheadend as the backend; then we would have the best of both worlds.

I love Tvheadend, but I loathe Kodi and its developers. They should just leave those parts of Kodi that work well alone. But I have read that they don't even play well with each other, and I get the distinct impression that at least one or two of them more or less detest their users. I was only half kidding when I said I think some of them get some perverse joy out of tormenting their users, by breaking functionality that formerly worked well. There's really no good reason for them to do shit like this; it would be one thing if passthrough audio had never worked, but it's worked fine for several versions now, so why screw it up?

I know that Tvheadend is in and of itself a full time endeavor, and that there's not a large group of people behind it, but how I wish sometimes that there was a native frontend to go with Tvheadend so we don't have to either use Kodi, or else settle for a barebones player (with no remote control support) such as VLC. As I said I always thought MythTV had one of the best frontends I've ever seen (it worked so much better than Kodi in so many ways) but their backend software was a little slice of hell to try to configure even just for normal over-the-air TV, and satellite TV was a total non-starter. And since it is against my religion to run a server on Windows ;), Tvheadend and MythTV are really the only two choices for a Linux-based PVR (and again, I have no problem with Tvheadend, it's entirely with Kodi).

Robert Cameron

The reason it changed is because Kodi is restructuring and rewriting much of the backend code. This is to allow for much greater flexibility and more robust support for input types going forward. As to the PVR changes, starting with 17, Kodi completely changed how PVR clients were handled internally. The next version is bringing more changes and improvements to the PVR subsystem, but these had to wait until the foundation was in place.

I'm not saying the removal of passthrough for Live TV doesn't suck, and I personally am not a Kodi dev, but I understand what changed and why. Sometimes you have to take a step backward in order to make going forward easier; the path Kodi was previously on was headed towards a dead-end, so they're backtracking a little in order to change direction so that the project can continue forward and not hit the dead-end.