Free online 3GP to MJPG converter

Older mobile phones and 3G video archives commonly use 3GP, while some editors, capture systems, and legacy devices require Motion JPEG video. Converting the file decodes the original 3GP stream and re-encodes each frame as MJPEG, usually producing a more editable but larger file.

What the 3GP format is

3GP is a multimedia container specified by the 3rd Generation Partnership Project for mobile networks and handsets. Phones from the 2000s and early 2010s commonly saved camera recordings as .3gp files using H.263, MPEG-4 Part 2, or H.264 video with AMR-NB, AMR-WB, or AAC audio.

You may encounter 3GP files in old phone backups, MMS attachments, exported mobile-camera clips, and recordings made by Nokia, Sony Ericsson, Motorola, Samsung, and other 3G-era devices. Modern desktop players often support the format through FFmpeg-based codecs, but older 3GP files can still have unusual frame sizes, audio tracks, or codec combinations.

What the MJPG format is

MJPG usually means Motion JPEG: a video stream made from independent JPEG-compressed frames. Unlike H.263, MPEG-4, and H.264, it does not use inter-frame prediction, so every frame can be decoded independently.

MJPEG is useful for video editors, frame-by-frame processing, machine-vision systems, webcams, industrial cameras, and older capture hardware. Independent frames simplify seeking and editing, and decoding requires relatively little processing. The trade-off is a much larger file because JPEG compression is applied separately to every frame.

The target may be a raw MJPEG stream with an .mjpg extension or an AVI container whose video codec is MJPEG, often described as MJPG. Check the receiving program's specification before choosing the output container; changing the extension alone does not convert the codec.

How to actually convert 3GP to MJPG

For a desktop conversion, FFmpeg provides direct control over the codec, quality, frame rate, and container.

1. Install FFmpeg and place the source file in an accessible folder.
2. Inspect the streams with ffprobe input.3gp if you need to confirm the video dimensions, frame rate, audio codec, or duration.
3. For an AVI file containing MJPEG video and PCM audio, run ffmpeg -i input.3gp -c:v mjpeg -q:v 3 -c:a pcm_s16le output.avi.
4. If the target specifically requires a raw MJPEG stream with no audio, run ffmpeg -i input.3gp -c:v mjpeg -q:v 3 -an -f mjpeg output.mjpg.
5. Open the result in the required application and verify that the frame rate, dimensions, playback duration, and audio behavior meet its requirements.

FFmpeg's JPEG quality scale runs from 2, which is very high quality, toward 31, which is lower quality; -q:v 3 is a practical starting point. Use -q:v 5 or -q:v 7 to reduce size, or a lower value when preserving detail matters more than storage.

For a conversion without installing software, upload the file to the free converter on 101convert.com, select MJPG as the output format, and download the converted file. The service may choose a particular container or omit audio, so verify the resulting file's technical requirements.

Quality and compatibility limitations

This conversion is normally lossy twice: the original 3GP video has already been compressed, and MJPEG applies another lossy JPEG encoding to each decoded frame. Increasing MJPEG quality cannot restore detail discarded by the 3GP encoder.

MJPEG output is often several times larger than the source. It also may not preserve 3GP audio when producing a raw .mjpg stream, because that format commonly carries video only. Use AVI with pcm_s16le when the destination needs uncompressed audio alongside MJPEG.

Keep the original frame rate and dimensions unless the receiving device specifies different values. If required, add options such as -r 30 for 30 frames per second or -vf scale=1280:-2 for a resized output; these settings can duplicate, drop, or resample frames and cannot improve the original resolution.