Question for the pros. Is there a tool that I can use that will use my current MP4 encoded with an AC3 5.1 track and remux an AAC audio track from the AC3 audio as a second track without having to recode the video?
If you already have the AAC track from another video file, you can use MKVToolnix to add it to your container. And if they are a bit out of sync you also add a delay to it.
It’s gonna take you less than a minute to do all that.
I do not have a separate AAC track, I can burn ones if I must, trying to add a second track to my MP4’s which all are in AC3 by using that track and adding an AAC as an alternate track. Any tools that will do that?
Like I said, once you have the track you can just embed it into the mkv container and have both recognized by Plex. This is just remuxing.
If you only have the AC3 track then you’ll need to encode that to AAC first before adding it to the mkv container
I get that, Can MKV take an MP4 with AC3 and copy /convert and add it as a second track AAC? Looking to streamline the process.
Yes. MP4 as MKV is just a container. You can also append subtitles, cover and other metadata to your final file.
MKVToolnix cannot convert anything, as far as I know. You’ll need to use a separate program to covert the audio, unless there’s some utility that has that built in utility. I’m not aware of any, though, but I’ve never looked…
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You can copy existing tracks and add an AAC track created from the AC3 track.
Works with both MKV and MP4 containers.
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what he said.
(I’d use ffmpeg with libfdk_aac to extract-and-convert the audio, and either MP4Box, ffmpeg, or mkvmerge (from MKVToolNix) to mux together a new file containing the desired tracks.)
But, do you need to?
AC3 is a very widely-supported audio codec. Are you sure your playback devices don’t support it?
On all but the very slowest servers, Plex can happily transcode audio at playback time.
Plex is going to choose the first/default audio track and transcode it if necessary. It’s not going to choose an alternate track to avoid transcoding. You’d have to manually choose the alternate track.
Plex will automatically transcode as necessary if you Sync/Download/Optimize media.
Transcoding in advance won’t noticeably improve quality.
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Thanks you answered my thoughts quite well. I was going to toy with 2 tracks, the AAC was to provide. pass-thru direct play on the Audio. I never had any problems with my current set up of mp4 with AC3, I was just curious how much that would impact making the audio available as an AAC to avoid some instances of transcoding.
Sounds like it really is not worth the effort though.
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