There are various browser add-ons that are supposed to extract and save the audio streams from video, or at least there used to be. I've not bothered with it for years, because they rarely worked, and never worked for long.
Is there anything public domain that will pull the audio stream out of MP4 files already on the computer? Something with an actual GUI? My full time job does not give me time to studio audio engineering or learn complex command line scripting, so I can't get elbow-deep into ffmpeg and such.
Please help out if you have the time. Thank you.
mp4creator will do the job. First list all tracks with -list, identify ID of audio track, then extract it with -extract=<track-id>.
MP4Muxer is GUI for mp4creator.
I just found out AVC (Any Video Creator) does this. Will convert to a number of popular music formats. I think this means it's time to pay for the full version!
You can do the same using ffmpeg for free.
Pazera Free Audio Extractor (http://www.pazera-software.com/products/audio-extractor/) can extract audio from most video's, and if i recall correctly, it uses ffmpeg
FFmpeg is very easy to use for this. The only command you need to run is:
ffmpeg -i input-video.mp4 -vn -acodec copy output-audio.mp3
Would this work if you provided a link to a youtube vid?
Youtube rarely uses MP3 if they use it at all, even. (I haven't come across MP3 audio in any Youtube video for years and years.)
Op asked for a solution with a GUI, unfortunately I don't know of any. To me it sounds as if Op desires to download audio from things like Youtube videos.
In any event, Youtube doesn't put MP3 into their videos. They use Opus and AAC (MPEG-DASH).
However there are easy ways to get the audio from a Youtube video, using youtube-dl:
$ youtube-dl -f bestaudio --extract-audio <youtube-link>
By default, youtube-dl selects the best audio quality anyway, so not specifying -f bestaudio
creates the same results.
As I said before, this is rarely if ever an MP3. It usually ends up as an .opus
That being said, youtube-dl can convert files into a target format:
$ youtube-dl -f bestaudio --extract-audio --audio-format mp3 --audio-quality 0 <youtube-link>
This will use FFmpeg to convert whatever audio into MP3. Personally, I highly advise against that.
Youtube-dl is available here: https://youtube-dl.org