Why compress a format that is already small
3GP was designed for phones with tiny screens and slow networks, so most old clips are only a few megabytes. Today people compress 3GP for different reasons:
- a basic phone or a simple music player only plays 3GP from its memory card, and the card is full;
- an MMS message or an old mobile service accepts only very small files, often well under 1 MB;
- a modern video should be turned into a tiny 3GP for one of these devices;
- some Android apps still save short recordings as 3GP, sometimes at a higher bitrate than needed.
Three codecs, three generations of phones
| Codec | File size | For |
|---|---|---|
| H.264 (default) | Smallest | Phones from about 2009 on, and modern players |
| MPEG-4 Part 2 | Medium | Feature phones of the late 2000s |
| H.263 | Largest for the same picture | The oldest camera phones; picture size is capped at 352×288 |
For old clips, the codec is often where the saving comes from. Their picture is tiny and the frame rate low, so there is little else to remove. Rewriting an H.263 clip with H.264 usually makes it noticeably smaller while it looks the same on screen.
If you are not sure what an old phone supports, copy a short test file to it first. If H.264 doesn't play, try MPEG-4, then H.263.
Getting under a strict size limit
The sound in the compressed 3GP is AAC at a fixed 96 kbps. That alone takes about 0.7 MB per minute. This matters when the limit is small. A one-minute clip can't fit into 500 KB with sound, whatever happens to the picture. The tool tells you when a target is out of reach and shows the smallest size it can make. You then have three options:
- tick Remove audio if the clip works without sound;
- shorten the clip with Trim Video or in the 3GP editor;
- lower the resolution to 360p or less and the frame rate to 15 fps, which old phones played anyway.
Small phone screens hide most compression artefacts, so even the Smallest level usually looks acceptable on the device itself.
Speed and privacy
3GP is written by a built-in converter engine (ffmpeg compiled for the browser). It is slower than the browser's MP4 encoder, but 3GP clips are short and small, so a batch is usually done quickly. If you want to watch old phone videos on a computer or TV instead, convert them with 3GP to MP4. Nothing is uploaded at any step.