Plex not able to play APAC (Apple Positional) Audio

Plex Players Streaming Devices
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Server Version#: 4.148.0
Player Version#: 2025.24.0
I record videos on my iPhone 16 Pro (iOS 18) with audio in “Spacial Audio” format (see Settings→Camera→Record Sound). I don’t remember if this is the default or not. When this is set, iOS creates two audio tracks, with APAC (Apple Positional Audio Codec) as the default, and AAC (stereo) as alternate. APAC as recorded is either 3.1 or 4.0 surround (I’m seeing it both ways in the docs and UI).

I’ll often import these recordings via Image Capture, and save them to my Home Videos folder which is a Plex library.

When I attempt to play these videos on my Apple TV 4K, Plex shows an error:

Could not transcode because:

Cannot convert this item.

Implementation for audio decoder

‘apac’ not found.

I can manually change the audio channel to AAC, which plays fine. While I can hear the audio, it’s using two-channel stereo rather than surround (positional) as is the audio’s intent. The AppleTV (as of tvOS 17, from fall 2023) has a built-in decoder for APAC audio.

Primarily I am curious what steps are required on the Plex development side to play APAC audio. My primary use is on Apple TV, but the format should be translatable in some way to other formats. I’m happy to help if possible.

Secondarily, I’m wondering why Plex doesn’t try the two-channel AAC audio when it recognizes it cannot play the primary APAC audio channel. This leads to me changing the audio channel for each video, which gets old fast.

I encounter the same issue when using Plex’s web client. I’m less surprised Plex web cannot play APAC, but again I’m surprised it doesn’t simply play the AAC audio.

If helpful, Apple’s documentation on the APAC format is here:

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2

Don’t have answers as far as plex support, but I can confirm that positional audio seems to be on by default. I definitely didn’t go to turn it on on my phone anyway, but it is recording that for all videos for me

3

As far as I understand it, APAC is currently a wholly proprietary technology owned by Apple. Plex has no support for it to be able to use it in any way.
Particuarly it is not able to convert it so it could be played back in Plex clients on different devices which are not made by Apple.

Plex can only use a secondary audio stream if that stream is stored as a wholly separate audio stream in the file. If it is somehow combined into the APAC stream (which I suspect is the case), Plex cannot decode it.

4

Yes, APAC is a proprietary audio format. Apple provides APAC decoding within by any app running on its operating systems (using AVAssetReader, afconvert, and maybe other ways). APAC audio is also supported in Safari.

I would not expect Plex to decode APAC on non-Apple platforms until the format is fully documented for use on non-Apple platforms.

For a brief overview of APAC, watch the last three minutes of this Apple developer video: Learn about the Apple Projected Media Profile - WWDC25 - Videos - Apple Developer.

All APAC videos with APAC audio streams that I’ve seen also have standard two-channel AAC streams. Plex plays these streams fine when manually selected. The issue here is Plex uses the APAC stream as default, tries to play it, and fails. I would expect Plex to recognize it cannot play APAC (until it can, of course) and fall back to AAC on its own, rather than failing with an error.

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Or fail with an error that gives the option to select a different audio stream to proceed with? Which would help in the case of multiple streams to choose from.

6

I second this. It has made using plex for home videos a pain. Plex, please offer the ability to set preferred audio settings or automatically avoid APAC if possible.