I'm just converting an MP4 video file to MP3 file. So it should be extracting audio from the video mp4 file to an mp3 file :-)
Software i'm using is called Free M4a to MP3 Converter 9.3.
http://www.maniactools.com/es/soft/m4a-to-mp3-converter/
I'm going to confirm what i've just said by opening output folder and check mp3 file :-)
Perfect, i just converter 529 MB of video to 476 MB of audio. Free M4a to MP3 Converter 9.3 works fine with MP4 and extract audio from video file :-)
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