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AAC 5.1 isn't working (center on right channel)

EldiegorinoEldiegorino Posts: 25Members, Plex Pass Plex Pass

The sound of all my movies using AAC 5.1 is messed up: the center channel is completely playing through the right channel. No matter what I do all AAC 5.1 movies are unwatchable, the sound is totally annoying... Somebody any idea how to fix this or having similar issues? Thanks!

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Best Answer

  • JigShaunJigShaun Posts: 20Members, Plex Pass Plex Pass
    Accepted Answer

    I'm having exactly the opposite problem. The few AAC files I have are playing fine, but every AC3 file is switched right for center. I MAY know why this is an issue (at least for me). I'm a recording engineer and I work with AC3 (Dolby Digital) all the time, but never with AAC. It might have to do with how the formats map their audio channels. AC3 arranges their 6 channels like this. L/R/C/LFE/Ls/Rs. So the three front channels are arranged Left/Right/Center. I did a little research today and I'm still not completely sure what's going on in the back, but in the front, AAC files seem to be mapped L/C/R. so

    AC3 = LEFT / RIGHT / CENTER
    AAC = LEFT / CENTER / RIGHT

    This seems like it might be a reason why I am having a problem. It doesn't explain why YOU are, since PLEX for PS3 is supposed to be AAC compatible. I'm assuming that it's PLEX decoding the AAC audio, since there are almost NO TVs or Receivers that know how to handle AAC. Even more confusing, it doesn't explain why MANY people aren't having this problem with their AC3 files. Also, PLEX is supposed to be able to "Allow Direct Play of AC3 Audio" but I can't get that to work either. I wish I could be of more help, but I can't even fix my problem, let alone help with yours. I only installed PLEX two days ago, and my understanding is the software for the PS3 is pretty new too. But according to PLEX, MP4 with AAC should be supported, so maybe somebody out there knows how to fix it. Can I ask what kind of computer and what OS your server is running?

    I know almost nothing about PLEX yet, but here are a few things you might want to try. In the server there's a setting Allow Direct Play of AC3 Audio. Try turning that on or off. You might also want to toggle Direct Play, Direct Stream, and Prefer AAC Audio. Best of luck.

Answers

  • JigShaunJigShaun Posts: 20Members, Plex Pass Plex Pass
    Accepted Answer

    I'm having exactly the opposite problem. The few AAC files I have are playing fine, but every AC3 file is switched right for center. I MAY know why this is an issue (at least for me). I'm a recording engineer and I work with AC3 (Dolby Digital) all the time, but never with AAC. It might have to do with how the formats map their audio channels. AC3 arranges their 6 channels like this. L/R/C/LFE/Ls/Rs. So the three front channels are arranged Left/Right/Center. I did a little research today and I'm still not completely sure what's going on in the back, but in the front, AAC files seem to be mapped L/C/R. so

    AC3 = LEFT / RIGHT / CENTER
    AAC = LEFT / CENTER / RIGHT

    This seems like it might be a reason why I am having a problem. It doesn't explain why YOU are, since PLEX for PS3 is supposed to be AAC compatible. I'm assuming that it's PLEX decoding the AAC audio, since there are almost NO TVs or Receivers that know how to handle AAC. Even more confusing, it doesn't explain why MANY people aren't having this problem with their AC3 files. Also, PLEX is supposed to be able to "Allow Direct Play of AC3 Audio" but I can't get that to work either. I wish I could be of more help, but I can't even fix my problem, let alone help with yours. I only installed PLEX two days ago, and my understanding is the software for the PS3 is pretty new too. But according to PLEX, MP4 with AAC should be supported, so maybe somebody out there knows how to fix it. Can I ask what kind of computer and what OS your server is running?

    I know almost nothing about PLEX yet, but here are a few things you might want to try. In the server there's a setting Allow Direct Play of AC3 Audio. Try turning that on or off. You might also want to toggle Direct Play, Direct Stream, and Prefer AAC Audio. Best of luck.

  • EldiegorinoEldiegorino Posts: 25Members, Plex Pass Plex Pass

    Hi JigShaun,

    thank you for the insights about the channel arrangements of AAC and AC3 5.1! The Plex Server is running on a Lenovo ThinkPad X250 (dual core i7, 16 GB RAM, LAN wired).

    Maybe I'm able to help you, because I also had the very same issue with AC-3 on my PS3/4. At least I was able to solve it by activating in the settings section of the PS3 or PS4 Plex App "Dolby Digital AC3". It's worth a try.

    Btw: I think that your answer really explained my problem - I'm using a Sonos Surround System, due to the fact that the Sonos system can handle only AC-3 streams directly, I deactivated within the Playstation Sound Settings all other options (I marked just AC-3 Dolby Digital and PCM). I guess, that this could be the reason. However, I don't understand why the Playstation is not able to match the channels... Maybe because the Playstation is not transcoding the AAC input in AC-3 but generating a PCM output and leaving the channel arrangement as it is? Still confusing ;-)

    Anyway, thank you again and good luck with your AC-3 problem!

  • JigShaunJigShaun Posts: 20Members, Plex Pass Plex Pass

    Thanks for the suggestion. I'll give it a try. I did the same thing you did. I'd originally just let the PS3 automatically choose audio outputs and it selected just about everything. Unfortunately, it was just sending all the media to my receiver as PCM 7.1. So I deactivated everything on the PS3 except the Dolby Digital and DTS options. It didn't solve my Right/Center problem but at least it started sending and actual AC3 stream to the amp. I think you're also right about the PS3 not transcoding. I suspect as long as the game console knows your Sonos system can decode the audio, it's probably just sending the stream back out the same way it came in. What does confuse me about your problem though is that PLEX doesn't support AC3 yet, but it IS supposed to support AAC. Is it all your AAC content? Do you have any AAC-2ch files? Does it mix them up as well? I assume your ThinkPad is running some version of Windows? One of my concerns is that my server is an iMac with a brand new OS X. So if your suggestion doesn't work the next thing I'm going to try (I think) is installing an older OS on an external drive to see if that makes any difference. What I really don't get is that neither of us is running anything out of the ordinary, so why aren't there a whole bunch of people complaining of the same problem? Good luck. Let me know if you get yours working.

  • EldiegorinoEldiegorino Posts: 25Members, Plex Pass Plex Pass

    Yes, it's Windows 8.1 Pro 64 bit. I don't think that the problem is related to the server, because the problem exists just when I'm using the PlayStation App. The channel mismatch occurs only (but every movie) with AAC 5.1 - AAC 2.0 works usually fine. However, the AC-3 sound is better. If you have the possibility you should try the app on another device to determine if the reason is the app rather than your OS (what I would assume). Yes, it is really strange that there is nobody else with similar problems. I found an old discussion, January to April 2015, that ends more or less abrupt and without a clear solution:
    https://forums.plex.tv/discussion/142073/plex-for-playstation-5-1-aac-audio-issues
    It's interesting, that there seems to be similar AAC issues also when using other Apps:
    https://forums.plex.tv/discussion/177393/aac-5-1-on-fire-stick
    Maybe there are not enough people using these devices to let Plex work on this? Or maybe it’s really just us and just a couple of other user?

  • AJHarperAJHarper Posts: 9Members, Plex Pass Plex Pass

    So I'm not losing my mind. I'm running PLEX through my living room PS3 and all the voices are coming through the right speaker as opposed to the center speaker. I feel since I pay annually (as I'm sure many do) for this service that PLEX needs to address this. It doesn't happen on my PS4 but that is up in my room. I don't want to go out and buy another PS4, Xbox One, or whatever just because PLEX has known about this issue for almost a year at minimum and refuses to fix it. Please fix this!

  • AJHarperAJHarper Posts: 9Members, Plex Pass Plex Pass

    @AJHarper said:
    So I'm not losing my mind. I'm running PLEX through my living room PS3 and all the voices are coming through the right speaker as opposed to the center speaker. I feel since I pay annually (as I'm sure many do) for this service that PLEX needs to address this. It doesn't happen on my PS4 but that is up in my room. I don't want to go out and buy another PS4, Xbox One, or whatever just because PLEX has known about this issue for almost a year at minimum and refuses to fix it. Please fix this!

    One of the links above solved my issue. The one where he said to enable AC3 in the PS3 app settings. I apologize for being a whiny baby. My audio seems to be working fine now. I should have read the other links before complaining.

  • EldiegorinoEldiegorino Posts: 25Members, Plex Pass Plex Pass

    It is also true that the PS4 App do not have problems with AAC 5.1 However, activating the AC-3 option in the Plex App Settings on the PS3 do not solve the AAC 5.1 problem for me, just AC-3 is working fine when it is activated, AAC 5.1 ist still producing a channel mismatch. I'm using the PS4 now, even if PS3 is much better to use to watch movies due to the RC - which is still missing for the PS4 system...

  • JigShaunJigShaun Posts: 20Members, Plex Pass Plex Pass

    Just so I'm clear. Are you talking about the Audio Output Settings on the PS3 console? Or activating the button "Allow MP4 videos with AC3 audio to be played directly" in the PLEX settings on your computer? Neither makes a difference for me. And the problem occurs on both my 1st gen PS3 and my 2nd gen PS3. At least I'm relieved that other people are having this problem. I was beginning to think it was just me. Though mine seems to be the opposite of people in this thread. My AAC files work fine, it's all my Dolby Digital movies (which there are many more of) that are reversed.

  • EldiegorinoEldiegorino Posts: 25Members, Plex Pass Plex Pass

    I guess that you are looking in the wrong settings - please open the plex app of your PS3 ang click on your user name in the upper right corner, than go to settings and activate in the options "Audio" the "Dolby Digital (AC3)". That's it - I hope so ;-) Good luck!

  • JigShaunJigShaun Posts: 20Members, Plex Pass Plex Pass

    Thank you for the more precise instructions, but I think the Windows and Mac Servers are different. My settings doesn't have an "Audio" option. I have to choose "Settings/Web/Player/Audio & Subtitles. There I get choice "Allow Direct Play of AC3 Audio. Allow MP4 videos with AC3 audio to be played directly." I can turn on or off. I've been through every setting in the Plex software and that's the only one that refers to AC3. I've tried it both ways a number of times with no success. I'm going to try encoding a few movies with dual AC3 and AAC audio streams, but I suspect I'm just going to have to wait until either Plex gets this straightened out, or I bite the bullet and by a new Apple TV. I really don't like the way AAC surround sounds, so I'm pretty much stuck for now.

  • DontWorryScroDontWorryScro Posts: 4Members, Plex Pass Plex Pass

    @JigShaun said:
    Thank you for the more precise instructions, but I think the Windows and Mac Servers are different. My settings doesn't have an "Audio" option. I have to choose "Settings/Web/Player/Audio & Subtitles. There I get choice "Allow Direct Play of AC3 Audio. Allow MP4 videos with AC3 audio to be played directly." I can turn on or off. I've been through every setting in the Plex software and that's the only one that refers to AC3. I've tried it both ways a number of times with no success. I'm going to try encoding a few movies with dual AC3 and AAC audio streams, but I suspect I'm just going to have to wait until either Plex gets this straightened out, or I bite the bullet and by a new Apple TV. I really don't like the way AAC surround sounds, so I'm pretty much stuck for now.

    No no he means on the actual Playstation Plex app. Not on your PC/Mac based Plex Media Server. When you load up Plex on your Playstation use your remote control to select your username up at the very top right. There you select "Settings" then select "Audio" then tick the AC3 box.

  • beren12beren12 Posts: 7Members, Plex Pass ✭✭

    Any fix? This is happening with my aac7.1 and apple tv… infuse plays it fine

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