Solved Encoding Additional Audio Track Into an MP4 File

[TheDeerDude]

Let's say I have an MP4 file with video and a single soundtrack for "English". How could I possibly add (encode?) another track, with a different language, into the existing MP4 file, so that it can be selected in WMP or VLC under the audio/languages menu?

It'd be much more efficient than having 2 or more large files just for different languages

 

[badcrc]

You can add a 2nd soundtrack with Avidemux (despite the name, it also handles mp4, mkv etc - just remember to set the output container). The video can be left on copy.

avidemux | SourceForge.net

it also does basic editing, trimming etc

 

[TheDeerDude]

Sweet, that's a keeper. Those other options will come handy in the future. Thank you so much, it does just what I need it to

For future reference:
Menu > Audio > Select Track (Select 2nd Track > "... add audio track")

 

[badcrc]

re : Avidemux editing/trimming - if you navigate through a movie using up/down arrows, so you are always on an I frame when cutting, no recode is required. Just leave the video + audio on copy, and it's really fast. Cutting on any other type of frame means a recode.

Another use for Avidemux is boosting audio in a quiet movie. Leave the video on copy and use the audio filter to boost, say, 12 dB. You can also adjust audio delay to fix out of sync problems.

 

[TheDeerDude]

Thanks for those tips. The second one came in handy, however the audio is still misaligned later on, it seems that the video is slightly slower than the audio. That's not as easy to fix unfortunately.

 

[badcrc]

As a temp fix for out of sync audio, VLC player lets you adjust audio delay +/- in 50ms steps on the fly. Hot keys are J/K. If the audio is out by a constant amount, you can get the value this way to use in Avidemux for recoding.

With the problem you mention of the soundtrack being the wrong length, although you can stretch/shrink an audio track using, say, Audacity (Effects, change tempo), then remux it, I've never had much success with that.

VideoLAN - VLC: Official site - Free multimedia solutions for all OS!
Audacity: Free Audio Editor and Recorder

VLC is also useful for quiet movies - using the mouse scroll wheel, you can push the volume upto 200%. Saves recoding.

 

[TheDeerDude]

I've been using both - VLC and Audacity for a while now, but I'm just starting to discover their functionality other than video playback and sound recording, haha.

I will try compressing and altering the audio, so it's slightly shorter but sounds the same, that will do for me.

Thank you for being so helpful