Server Version#: 1.19.5.3112
Player Version#: 8.4.2.19372
Hi all, I noticed a while ago that whenever I start playing content with a multi-channel AAC stream, Plex would then transcode said stream to AC3 because it thinks my TV doesn’t support multi-channel AAC. Well, I had a look around the forums and found a thread where someone was having a very similar (if not the same) issue as me: Link to old thread of same issue
Skimming through it, the issue was apparently solved with an update to the Plex client, however that thread is quite old (last update from plex staff was June 2019) and now, even on the latest client of 8.4.x, I am still facing the issues described in the thread.
Just to clarify, I do believe that my TV actually supports multi-channel AAC just fine. Playing the file directly on my TV (whether through the built-in “Videos” app or the VLC app) poses no issues and plays without problem. So, I’m not sure why Plex is suggesting otherwise (perhaps my TV doesn’t explicitly say it supports multi-channel AAC to apps?).
The only way I found to supposedly “solve” the problem is to go into the profiles folder (where PMS is installed) and manually change the ‘audio.channels’ limitation from 2 to 8 in ‘Android.xml’. This does finally allow for the multi-channel AAC audio to be played (with no issues, stuttering etc. Playing just fine), however, plex was still doing some kind of transcoding as it said “direct streaming” (as evidenced below).
What this means is waiting when the video is first selected, so that it can be buffered, and once I’m in the video, be subject to buffering again anytime I try to skip around. Honestly, I wouldn’t have cared about the audio transcode if it wasn’t for this reason but it’s very frustarting.
I’ve included a log below from the Plex client on my Android TV (I start playback around 17:05) and would really, really appreciate it if anyone can help out in resolving this.
It doesn’t look like anything is being transcoded - technically - it looks like Plex or Sony doesn’t like the cut of that MKV file - and is making a new one - for some reason - in that Mux Plex is reporting (it calls those transcodes - technically, I guess they are).
But in the end, AAC 5.1 is NOT an industry standard by any means. It’s what some scene group came up with and arrives, along with bogus embedded metadata (in for a penny…), to make our lives miserable.
You know what I do?
I change every AAC 5.1 to AC3 5.1 in a few moments of Xmedia Recode interaction - while I’m normalizing to 84db (I’d be doing that anyway), while correcting any number of other scene group ‘features’, and muxing into an MKV file, before it hits the Plexiverse. A few moments of prevention is worth a lifetime of PITA.
Problem solved.
That’s me. Not sure what you’ll do - other than wait for some good/bad news from higher up the chain.
There are several log entries such as:
08-10 16:57:31.248 i: [FFmpeg] [ERROR] [matroska,webm @ 0x7d6ca200] Element at 0xa447 ending at 0x12b5d exceeds containing master element ending at 0xa43b
Try remuxing the file into a new MKV container with MKVToolNix. That sometimes straightens out troublesome MKV problems.
Drag the file into the Multiplexer window and select “Start Multiplexing.” It will not alter any audio/video/subtitle tracks. It will copy them into a new MKV container.
@MagaZine, did you see this comment in that thread? He suggests looking at your “Passthrough” settings.
I notice that you have PGS subtitles enabled. Does disabling those change anything? I expect the Android app to be able to render those natively without transcoding, but I also know that the mere presence of subtitles in an MKV can cause some TVs to barf.
I agree with the suggestion to try remuxing the file. It’s odd to me that it says MKV → MKV like that.
Your logs look funny to me, but I’m not familiar with the device logs. It decides not to use AAC, except then it uses AAC? Kinda hoping somebody will explain them better.
That’s not wrong, but it is an imprecise statement. If AAC is the audio portion of MPEG-4, that’s about as standard as it gets. HE-AAC 5.1 is even used sometimes for digital broadcasts in the non-ATSC world.
The scene is, surprisingly to me, rather conservative and self-regulated. Maybe that’s a side topic - bogus embedded metadata? I’ve got a penny to spare.
I agree that AC3 is more likely to be supported by consumer surround processors. Dolby has good tech AND bribed the right people at the right time. And I think we agree about encoding AAC 2.0 + AC3 5.1 for maximum compatibility. I’m guessing this example came from a Blu-ray (because of PGS subs) and I’m confident neither of us would have encoded it this way.
But I’ve also had good luck with AAC 5.1. Player boxes decode it into PCM or convert it to AC3. Or Plex converts it to AC3 before sending it to my Roku. And AAC 5.1 works fine on my phone and in my browser.
I hate reencoding, especially if I believe it should work as-is. I’ll do it when necessary - no use letting stubbornness prevent me from watching Supergirl - but I’m unlikely to keep a multiply-mutilated file around. I’d be more likely to redo it from the original encoding (or download a different source, if that’s your thing).
My TV wouldn’t have to puke up an AAC 5.1 hairball more than once before I started taking some preemptive action. In fact, I’m absolutely positive one of these Rokus horking up pavement-pizza on AAC-5.1 is the reason I don’t have any - 'cause they all get changed to AC3-5.1 before they find residence in storage around here.
an mp4 file is inadequate for anything other than AAC-2.0 - the lowest common denominator and least to cause any fuss.
AC3-5.1 Direct Plays on everything in the Plexiverse - that I care about.
Anyone thinking I can hear the difference in AAC-5.1 converted to AC3-5.1 in one pass - the last one - before it hits my library is crazy. I can’t and neither can anyone else.
and…
Remember that Cheap Chinese POS we talked about already? Well it likes audio levels as close to 89db (and that IS an industry standard) as they can get. I have NEVER seen any AAC-5.1 or any other multi-channel audio above about 73db and for this piece of crap that’s like having Mute on. One pass through XR cures that nonsense and anyone thinking I won’t do it - is mistaken.
I HATE having the TV on 95 out of a 100 when I switch to any other audio - and then get blown through the picture window out into the front yard. I can also tell ya that didn’t happen more than about once either…lol
I can’t get the sound of a cat with a hairball out of my head now, thank you. LOL.
Pragmatically I can’t disagree - do what works for you. AC3 is “always” supported in the living room. And it would sidestep @MagaZine’s current problem.
I haven’t had trouble with AAC 5.1, not playback, conversion, or volume levels. It’s not a “weird” format. I wouldn’t be ready to give up, or commit to always reprocessing my media.
Hey @MagaZine, I’m still curious if you’re sending audio to a soundbar or receiver. When you play multi-channel AAC in “Videos” or VLC, does it downmix to stereo, or does it decode to multi-channel PCM?
