Take the audio out of a video
Load an MP4, MOV, MKV, WebM, or MPEG-TS file and write its audio track to an audio file. The video track is discarded and the waveform of the audio is drawn so you can hear what you are about to save.
Two paths lead out of here, and the difference matters.
Copy vs re-encode
Original copies the encoded audio packets straight into a new container. Nothing is decoded, so nothing is lost and the work finishes at read speed. An MP4 holding 256 kbps AAC produces an .m4a holding that same 256 kbps AAC, byte for byte.
Everything else decodes the audio and encodes it again: WAV and FLAC without loss from that point, MP3, M4A, and Ogg Opus with a second lossy pass. Pick one of these when the destination cannot read the source codec, or when you need a specific bitrate.
The rule worth remembering: extracting to MP3 from a video is two lossy generations, not one. If the file is going into an editor, take Original or WAV.
When Original is not offered
The option appears only when the source codec fits a container this tool can write. AAC lands in .m4a, MP3 in .mp3, Opus and Vorbis in .ogg, FLAC in .flac, and PCM in .wav. Screen recordings, phone video, and most downloads fall into one of those.
MKV rips are where it stops. AC-3, E-AC-3, and DTS are common in them and none can be muxed here, so those files get the decode path and the format picker.
Codec and container are separate things
.mp4 names a container, not a codec. What sits inside it is usually AAC, which is why the copy path so often writes .m4a: same codec, different wrapper. The Stats row under the controls reports the codec the probe found, so the choice is made with the file in front of you rather than from the extension.
WebM works the same way. It carries Opus or Vorbis, both of which belong in an Ogg container, which is what the copy writes.
Take a section
Drag across the waveform to mark a range, tick the range option, and only that span is written. Useful for lifting a quote out of an interview or a music cue out of a longer recording without exporting the whole thing first and trimming afterwards.
Silent video
A file with no audio track has nothing to extract, and the probe says so instead of writing an empty file. Some screen recordings are captured without audio, and some MKV rips keep their audio in a track the container does not mark as primary.