convert AC3 audio in my MP4 videos to AAC

[njitgrad]

I would like to know if it's possible to "easily" convert the AC3 audio in my .mp4 files (that were created using Handbrake) into AAC audio.

When I created the .mp4 files (using Handbrake) I only left in the AC-3 audio stream (I unchecked the AAC stream, which as it turns out was a bad move).

When I play those .mp4s from my Synology NAS to any of my networked Samsung TVs it works perfectly fine because of the transcoding being done on the fly by the media server hosted on the NAS.

The problem is if I copy the .mp4 files to a USB stick and attempt to play them directly on the TV by plugging the stick into the TVs USB port. I get an "unsuppored audio codec" error message on the TV.

Is there an easy way to convert the audio? I have hundreds of MP4s that I need to do this for.

[sneaker]

Try BOX4, Xmedia or - if you are familiar with cli software - ffmpeg.

Does your TV play AC3 in mkv? Most do. If so I would try to simply remux using mkvtoolnix. Very simple, very fast, zero quality loss.

[njitgrad]

Almost seems like Handbrake can do it for me. I have an .mp4 that only has an AC-3 track according to MediaInfo. When I open the .mp4 file in Handbrake it is telling me that there is an AAC and an AC-3 track. How could that be?

[sneaker]

HandBrake is probably telling you that the output will have an AC3 and and an AAC track, i.e. it will duplicate the input track. Not that the input already has them. HandBrake can convert AC3 to AAC but the problem is that it must always re-encode the video which costs a lot of time and also quality.

[njitgrad]

HandBrake can convert AC3 to AAC but the problem is that it must always re-encode the video which costs a lot of time and also quality.

I see. Probably not in my best interest if I lose video quality. Of all the applications you listed which would you consider the most straightforward to use? Can I set up to run a batch of mp4s?

[sneaker]

All of them have a batch mode AFAIK. All of them are quite simple.

I would try in this order:
1. mkvtoolnix
2. BOX4
3. ffmpeg (if you know cli - but it's not very difficult once you do)
4. Xmedia

[njitgrad]

Running each one of these tools is a one-step process?

I don't want to create mkvs from my mp4s, just convert the audio to AAC. Does that eliminate any in your list?

[sneaker]

Each program can do all of the work by itself. You only need to use one of them. (mkvtoolnix to create ac3-in-mkv - as I said: most TVs should play that just fine)

[njitgrad]

I just got BOX4 to convert an MP4 to AAC but now my question is this (I'm not that knowledgeable when it comes to audio channels)....
Will I have different playback sound for AAC than I did with AC3? Most of my TVs have a Samsung sound bar connected to them with a bluetooth subwoofer on the floor.
Will an AAC encoded file (since it's only two channels) sound differently than a AC3 file? I'm sure it will, right?

[sneaker]

Maybe. You can also create multi-channel AAC but not all players support it (higher licensing costs).


That's why I recommended to try AC3-in-MKV.

[njitgrad]

Maybe. You can also create multi-channel AAC but not all players support it (higher licensing costs).


That's why I recommended to try AC3-in-MKV.

Even if I converted an MP4 (with AC3) to an MKV (with AC3) I would still have the same issue of the TV not being able to play the audio, right?

[sneaker]

No, audio would most likely work. AC3 is very common in MKV. What exact TV model do you have?

[njitgrad]

No, audio would most likely work. AC3 is very common in MKV. What exact TV model do you have?

Well the thing is I'd like to play it on many different types of Samsung TVs.

[sneaker]

If it's older models you may want to activate some compatibility options:
MKVToolNixGUI->Preferences->Multiplexer->Default Values. There select: --clusters-in-meta-seek --disable-track-statistics-tags --engage no_cue_duration --engage no_cue_relative_position as default additional command-line options.
Also for batch mode go MKVToolNixGUI->Preferences->Multiplexer and select the bottommost option in "When dropping files". In MKVToolNixGUI->Preferences->Multiplexer->Output you can select default output folder (if you want).
Restart the app to make sure settings are applied.

Then you can just drag&drop as many files as you want and then and click "Start multiplexing" at the bottom.