Compress Video Without Wrecking the Audio
Audio is a small share of a video file and an enormous share of how finished it feels. People forgive a soft picture; they do not forgive muddy, warbling sound. The good news is that protecting it is nearly free.
Copy the track instead of re-encoding it
If the audio is already AAC — which it is for nearly all phone video and most MP4s — it can be copied into the new file untouched. Zero loss, zero time, and no second generation of compression. The compressor here does that automatically when you leave audio on "Keep original" and the container allows it.
Re-encoding is only necessary when the source uses something the container cannot hold, or when you deliberately want a smaller audio track.
What the bitrates sound like
| AAC bitrate | Sounds like |
|---|---|
| 192–256 kbps | Transparent, including music |
| 128 kbps | The sensible default; fine for almost everything |
| 96 kbps | Good for speech, slightly thin on music |
| 64 kbps | Clearly compressed, but speech stays intelligible |
| 32 kbps or below | Telephone. Only when the alternative is not sending it |
How much is audio actually costing you?
Over a 60-second clip, 128 kbps of audio is about 0.9 MB. In a 25 MB email attachment that is nothing — leave it alone. In a 3 MB MMS it is a third of the whole budget, and dropping to 64 kbps buys real picture quality. Work out the share before you economise: MB = kbps × seconds ÷ 8,192.
The mistakes that actually wreck audio
- Re-encoding repeatedly. Lossy audio degrades generationally, exactly like video. Copy where you can.
- Removing audio to hit a target. Almost always the wrong lever — resolution gives you far more room, and a silent video usually is not what you wanted to send.
- Downmixing without meaning to. Converting 5.1 to stereo is normal for sharing, but dialogue lives in the centre channel and a careless downmix can bury it.
- Mono at a stereo bitrate. If the source is mono, 64 kbps is genuinely equivalent to 128 kbps stereo. No reason to pay twice.
Compress an MP4 → Runs in your browser. Nothing is uploaded.