How to Extract Audio From a Video
Short answer
A video file already contains a separate audio stream, so extraction means decoding that stream and writing it to an audio file. The quality ceiling is whatever the video already contained — extracting to a lossless format cannot add detail that was never recorded.
Published
What extraction actually does
A video file is a container holding at least two independently compressed streams: one for picture, one for sound. They sit alongside each other rather than being mixed together.
Extracting audio means taking the audio stream and writing it out on its own. Depending on the target format this may involve re-encoding, or it may be a straight copy of the existing data.
This is why extraction is fast compared with video conversion — there is far less data, and often no re-compression at all.
Choosing the output format
MP3 is the pragmatic default. It plays on everything, and at 192 kbps or above it is hard to distinguish from the source for typical video audio.
M4A holds AAC, which is what most video files already contain — so it often means less re-encoding and slightly better quality per byte. It is the better choice for Apple devices and for audiobooks, where chapter support matters.
WAV makes sense only if you are feeding the audio into editing software that wants uncompressed input.
- Listening on any device → MP3 at 192 kbps or higher
- Apple ecosystem, or you want chapters → M4A
- Editing in audio software → WAV
- Speech only, and size matters → MP3 at 96 kbps is usually plenty
Why extracting to FLAC is pointless
FLAC is lossless, so it seems like the highest-quality option. But the audio inside a video file has already been compressed with a lossy codec — usually AAC.
Extracting it to FLAC produces a much larger file containing exactly the same already-degraded audio. Lossless means faithful, not restored. There is nothing to recover.
The only case where FLAC makes sense is when the source video genuinely carries lossless audio, which is rare outside professional masters.