Video to MP3

Search results for this job are dominated by two categories, and both are worth avoiding. There are ad-saturated converters that upload your file to a server you know nothing about, and there are site downloaders wearing a converter’s clothes.

This is neither. It accepts a local file and nothing else. There is no URL field, and there is no code path that fetches anything from anywhere. It is a file-in, file-out converter for video you already have: a lecture you recorded, an interview you filmed, a voice memo captured as video, a rehearsal you want as audio.

Because everything runs locally, there is also nothing to upload and nothing for us to store. That matters more than it might sound for this particular job, since personal recordings are the overwhelming majority of what gets converted.

Bitrate is how many bits per second the encoder is allowed to spend. More bits means a closer approximation of the input and a larger file. Two things are worth knowing before you reach for 320:

• You cannot exceed the source. The audio inside a video is already compressed, usually AAC at something like 128 to 256 kbps. Encoding that to a 320 kbps MP3 does not add information; it just spends more bytes describing the same already-lossy signal.
• Content decides more than the number does. Speech is overwhelmingly fine at 128. Music with cymbals, applause, and reverb is where lower bitrates produce audible smearing, because those are the hardest sounds to encode.

If you want the best possible result, use M4A passthrough. Copying the existing track is lossless by definition, because nothing is re-encoded at all.