Video files with 5.1 AC3 tracks are treated by default as 6 mono tracks

[morphinapg]

I'm using Premiere 24.5.0 on Windows 11 23H2

Every time I import a video file that has a 5.1 AC3 audio track, Premiere assumes it's 6 mono tracks instead of 5.1, and I have to manually set it every time. The only way I can fix this is by telling Premiere to default clips interpreted as mono to be interpreted as 5.1 (in Preferences/Timeline). While that will solve the issue with these particular files, if I happen to use a file with actual mono audio, that could cause a problem. I think that's probably rare enough for it to be worth doing in my case, but I think it's a bug that Premiere is interpreting files this way.

In my case, I'm using MP4 files with HEVC video and AC3 640kbps audio.

[R Neil Haugen]

In the Preferences/Audio you have options for the default behavior importing audio files, whether to use the file, or default to mono, stereo, or whatever.

What are your defaults set to?

[morphinapg]

By default that was set to "Use File". For now I've switched the mono section to 5.1, which does solve it, but the files should not be interpreted as mono in the first place.

[Kevin-Monahan]

Hi @morphinapg,

Thanks for filing the bug report. It seems you were able to work around the issue, however, I'm concerned that there might be a bug here still. I hope the product team will reply with some feedback for you. Perhaps @mstegner can reply. Sorry for the hassle.

Thanks,
Keviun

[Kevin-Monahan]

The status of this bug report has been updated.

[Kevin-Monahan]

This discussion might also help, @morphinapg: https://community.adobe.com/t5/premiere-pro-discussions/6-track-mono-2-stereo-5-1-stere-export/td-p/...

Thanks,
Kevin

[mstegner]

I’m not sure what your source file is like.  If you think this is a bug, we would need a copy of the file so we can reproduce this internally, otherwise there are too many variables for use to do anything.

Premiere can only interoperate the metadata in the file.  That is what the “Use File” settings is trying to do.  I suspect your file is set to explicitly tell Premiere to integrate the audio at mono.  And Premiere has no control over how the metadata is written into your source file.  This is explicitly why there is an override in the settings:  “Preferences>Timeline>Default Audio Tracks>5.1 media…” needs to be set to 5.1 (the default is “Use File”). 

This setting tells Premiere that anytime a file is imported that has 6 channels of audio, integrate it as 5.1.  Your file, I’m guessing, has some metadata tat is expectedly telling Premiere to treat the audio as mono.  That is just a guess as I do not have your file. 

I tested this with some files I have locally, that are h264 video and 6 channels of AC-3 audio (the file was created in Handbrake) and it imports as 5.1 when the “Use File” is selected. 

So I can only conclude that this is not a general bug with AC-3 audio, but something specific to your source file.

Perhaps you could start by posting the file for me to investigate, or even posting a screen shot of Media-info showing the files settings.

[morphinapg]

Here's a small sample:

https://drive.google.com/file/d/1Ub4GkHk14y6_Cw99TAvYHq4V7fQfqdU3/view?usp=sharing

Here's the mediainfo:

and here's what Premiere says in the project panel:

So it clearly recognizes it as 5.1, but for some reason decides to map it as 6 mono and I have no idea why.

Looks like I found another thread reporting the same issue:

https://community.adobe.com/t5/premiere-pro-discussions/sudden-change-in-import-a-single-5-1-audio-t...

[mstegner]

Perfect, Thank you so much for the sample file.  I've been able to replicate on my end.  Until there is a change, you will need to switch the source file to be interpreted  as 5.1. 
You can do this on import at “Preferences>Timeline>Default Audio Tracks....” To to already imported clips buy right clicking on them in the Project panel, Selecting “Modify>Audio Channels…” and selecting the 5.1 preset.

-Matt

[Kevin-Monahan]

Moving to Discussions.

[morphinapg]

has a fix been pushed?

[Tom Nord · Accepted solution]

Thank you for your report. However, due to the nature of the way Premiere Pro imports AC3 audio this is not something we have a lot of control over - for AC3 audio, Premiere Pro utilizes the platform's decoder rather than its own native decoder. The best way to work with these files on Windows is to do as @mstegner noted earlier: 

"...you will need to switch the source file to be interpreted  as 5.1. 
You can do this on import at “Preferences>Timeline>Default Audio Tracks....” To to already imported clips buy right clicking on them in the Project panel, Selecting “Modify>Audio Channels…” and selecting the 5.1 preset."