A video's sound is already compressed in an audio format of its own: usually AAC in MP4 and MOV files, Opus or Vorbis in WebM, MP3 in many AVI and FLV files. Extracting it without re-encoding copies that sound into an audio file exactly as it is: bit for bit the same quality, done in seconds even for long videos.
How to extract the sound unchanged
- Upload the video (up to 2 GB and 4 hours).
- Choose the format that matches the sound in the video:
- M4A for AAC (most MP4, MOV, M4V, 3GP and TS files),
- Opus or OGG for WebM and OGV files (Opus sound → Opus, Vorbis sound → OGG),
- MP3 for AVI, FLV and other files with MP3 sound,
- FLAC or WAV for lossless sound.
- Keep Keep the original sound unchanged switched on, and start.
The result says whether the sound was copied, for example “M4A, copied unchanged (AAC)”. If the sound is in another format than the one you chose, it is encoded at the bitrate you set instead, and the result says that too, including the source codec, so you know which format to pick to copy it next time.
Why it matters
Every lossy re-encode removes a little more detail. Copying avoids that, and it is much faster, because the sound isn't decoded at all.
Good to know
- AAC sound inside an M4A plays in practically every music player and phone. If a device only plays MP3, the sound has to be re-encoded.
- The main sound track is used; files with several tracks (for example two languages) say so in the result.
- Title, artist and album tags are kept; the video's location and date tags are not copied.
More about what this tool reads and writes: Extract Audio from Video.