AAC Audio Problem

[allmankind]

I am running the latest CoreElec release on my U9H and have been having issues with incorrect decoding of multi-channel AAC. Now I do not mean stereo, but 5.1 and 7.1 AAC audio. What usually happens is that the center channel gets lost or is severely muted.

The audio itself is fine, as the files in question play back fine on my computer. Under the Kodi Add-Ons section I see there is an AAC addon already installed and enabled. When I look in the repositories I cannot fine any other AAC addon options.

I am using a Denon AVR-X1200 receiver and using passthrough for audio in Kodi.

Any ideas/suggestions on how to resolve my AAC decoding issues?

 

[ArcticWolf]

I am running the latest CoreElec release on my U9H and have been having issues with incorrect decoding of multi-channel AAC. Now I do not mean stereo, but 5.1 and 7.1 AAC audio. What usually happens is that the center channel gets lost or is severely muted.

The audio itself is fine, as the files in question play back fine on my computer. Under the Kodi Add-Ons section I see there is an AAC addon already installed and enabled. When I look in the repositories I cannot fine any other AAC addon options.

I am using a Denon AVR-X1200 receiver and using passthrough for audio in Kodi.

Any ideas/suggestions on how to resolve my AAC decoding issues?

AAC audio doesn't use passthrough to the AVR, it's decoded on the U9-H & the AVR receives the audio as PCM.

Enter Kodi's settings -> System -> Audio, & try setting the number of channels in Kodi's audio settings from 2.0 to 5.1 or 7.1 (whatever the configuration of your surround speakers are). That may be all you need to do!!

If still no joy & you're watching a lot of media encoded in AAC you could also try enabling the "maintain original volume on downmix" setting, however, you'll want to disable that again when using passthrough for AC3, E-AC3, DTS, DTS-HD & TrueHD.

With Leia 18.1, when you're actually playing media as well, click on the settings cog, select audio settings & there's an option in there for "Downmix: Center mix level". Try tinkering with that & you can also apply it as the default for all media too. This setting allegedly doesn't affect media that would normally use passthrough to your AVR, (however, I've never needed to use it ).

The AAC add-on you've seen for Kodi is probably the AAC encoder for creating AAC encoded rips from within Kodi.

FYI....

 

[allmankind]

Thank you for your reply. Full of good information.

Yes, I am aware that AAC is not passed through, but decoded into PCM and that I believe may be where the issue is occurring. Normal mono and stereo AAC plays without issue, it is the multichannel AAC that is the problem. I do have my Kodi audio settings set to 5.1, as that is what I have.

I will play around with the "maintain original volumn on downmix" today and see what happens. By default I have that currently set to off. I also forgot that you can go into setting while playing a video. I will give that a try too.

Fortunately I don't have a lot of multichannel AAC encoded files, and what I do have is mainly old TV shows.

Very interesting chart, by the way. Thank you for that.

And here is a new issue I just ran into. I have some files AAC encoded (not multi channel) what will not play at all on Kodi. The video plays fine, just no audio, yet the audio plays fine on the computer. I will try your suggestions and see if I can get it to play properly.

Thank you.

 

[allmankind]

Well, I have had time to play with the audio settings. To my surprise, the "maintain original volumn on downmix" was on. I suspect I may have tried this previously in my attempt to fix multi-channel AAC. So I set it to off.

The results are good news, and bad news. The good news is that the absence of audio on those files is now working. The bad news, of course, is that the multi-channel AAC files did not improve at all.

 

[ArcticWolf]

Thank you for your reply. Full of good information.

Yes, I am aware that AAC is not passed through, but decoded into PCM and that I believe may be where the issue is occurring. Normal mono and stereo AAC plays without issue, it is the multichannel AAC that is the problem. I do have my Kodi audio settings set to 5.1, as that is what I have.

I will play around with the "maintain original volumn on downmix" today and see what happens. By default I have that currently set to off. I also forgot that you can go into setting while playing a video. I will give that a try too.

Fortunately I don't have a lot of multichannel AAC encoded files, and what I do have is mainly old TV shows.

Very interesting chart, by the way. Thank you for that.

And here is a new issue I just ran into. I have some files AAC encoded (not multi channel) what will not play at all on Kodi. The video plays fine, just no audio, yet the audio plays fine on the computer. I will try your suggestions and see if I can get it to play properly.

Thank you.

Well, I have had time to play with the audio settings. To my surprise, the "maintain original volumn on downmix" was on. I suspect I may have tried this previously in my attempt to fix multi-channel AAC. So I set it to off.

The results are good news, and bad news. The good news is that the absence of audio on those files is now working. The bad news, of course, is that the multi-channel AAC files did not improve at all.

No worries .

It's very easy to accidentally change a setting or miss it in the first place . Glad you caught it .

If that setting was already enabled AND you had the number of channels set to 5.1, then try the opposite, try 2.0 for the channels. See if that makes a difference too. Have a play around & you might stumble on something to correct the multi-chan AAC issues. Just remember what your default settings are for optimal passthrough for your high quality movie rips, that's all .

Obviously, the quality your recordings playback at will always be limited by the quality used by the "encodee"!! No given media player is perfect either unfortunately. Every so often I come across a file that plays perfectly with VLC on Windows but has lockups or buffers at the exact same spot every time with Kodi on Android for example. It's very hard to put an exact figure on it with the size of my digital collection but Kodi is certainly 99.7% or better for playback issues .

It could also be an issue with your specific AVR, (although I highly doubt it with a Denon but you just never know these days)!! Another "Trusted Helper" on this forum was having all sorts of problems with AAC files using an older audio set up. He recently upgraded to a dedicated AVR & all problems were instantly solved .

If it's one or two old box sets in SD with AAC audio, you might just have to put up with it or use another device to watch them & return to Kodi for everything else .

 

[allmankind]

When I was using android firmware, I too had a lot of playback issues when using Kodi. But since switching to CoreElec, 99.9% of my files play without issue. This multichannel AAC issue is the last real issue I have. Fortunately, it is only on a few TV series I have. I can live with if necessary. I was just hoping it could be easily resolved and someone might know the answer.

Thank you for all your help. Much appreciated.