MP3 (MPEG-1 Audio Layer III) is a lossy audio compression format. It discards parts of the sound that human hearing masks, producing files roughly a tenth the size of uncompressed audio.
Why it matters
MP3 became the standard for music and podcasts because it plays on nearly every device and browser. Quality depends on the bitrate: 128 kbps is acceptable for speech, 192 to 320 kbps for music. Newer codecs such as AAC and Opus can sound better at the same size, but compatibility favors MP3.
Because it is lossy, converting an MP3 back to a lossless format does not restore the lost detail.
Example
$ ffmpeg -i interview.wav -codec:a libmp3lame -b:a 128k interview.mp3A one-hour mono voice recording at 128 kbps is roughly 55 MB, since 128,000 bits per second times 3,600 seconds is about 57.6 MB.
Common mistakes
- Re-encoding an MP3 to MP3 repeatedly, which lowers quality each time.
- Using very low bitrates for music and hearing artifacts.
- Archiving master recordings only as MP3.
Related
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