Free online AVC to MJPG converter

What the AVC format is

AVC, also called H.264 or MPEG-4 Part 10, is a lossy video compression standard used by phones, cameras, screen recorders, video editors, streaming systems, and Blu-ray video. It commonly appears inside MP4, MOV, MKV, and MTS containers; files ending in .avc or .264 are often raw H.264 elementary streams without a container or audio track.

AVC compresses video across multiple frames, using predicted frames and reference frames to achieve small file sizes. A raw AVC file may not contain reliable frame-rate, resolution, duration, or audio metadata, so conversion software can require those values explicitly.

What the MJPG format is

MJPG, or Motion JPEG, stores each video frame as a separate JPEG image. It is a video codec rather than one mandatory container format; MJPG video is commonly delivered in an AVI file and can also be placed in MOV or other containers.

Because frames are independent, MJPG supports fast seeking, simple frame extraction, and compatibility with some older cameras, industrial systems, capture cards, and editing applications. Its main disadvantage is size: MJPG normally requires substantially more storage and bandwidth than AVC at comparable visual quality. MJPG does not preserve AVC's inter-frame compression structure.

How to actually convert AVC to MJPG

FFmpeg is the most controllable desktop method. Install a current FFmpeg build, open a terminal in the folder containing the source, and run:

ffmpeg -i input.avc -c:v mjpeg -q:v 3 -pix_fmt yuvj422p -an output.avi

This creates an AVI container with MJPG video and no audio. In FFmpeg, lower -q:v values produce higher JPEG quality and larger files; a practical range is 2 to 5. Replace input.avc and output.avi with the actual filenames.

If the raw AVC stream has no usable frame-rate metadata, specify it before the input:

ffmpeg -framerate 30 -i input.avc -c:v mjpeg -q:v 3 -pix_fmt yuvj422p -an output.avi

Change 30 to the source rate, such as 25, 29.97, or 60. An incorrect value changes playback speed and the output duration. If the AVC source is actually an MP4, MOV, or MKV file, use that complete filename instead of treating it as a raw elementary stream.

If the input contains an audio track and the target system accepts AVI audio, copy or re-encode it separately. For broad AVI compatibility, PCM audio can be used:

ffmpeg -i input.mp4 -c:v mjpeg -q:v 3 -pix_fmt yuvj422p -c:a pcm_s16le output.avi

For conversion without installing software, upload the file to 101convert.com, choose MJPG as the output, configure the available quality and container options, and download the converted file. Raw AVC files may need a manually supplied frame rate if their metadata is incomplete.

Quality, compatibility, and limitations

The conversion is normally lossy: AVC is decoded and then each frame is JPEG-compressed, so it cannot restore detail already discarded by the source. Avoid repeated AVC–MJPG–AVC conversions. Use a lower quality number in FFmpeg when preserving detail matters, but verify the resulting file size and the target device's supported JPEG sampling and AVI limits.

MJPG output is usually several times larger than the AVC source. It also may lack audio if the input was a raw .avc stream. AVI files larger than 2 or 4 GB can expose compatibility problems in older applications, so test the output on the intended device and split long recordings when necessary.

Some hardware accepts only a particular resolution, frame rate, JPEG chroma format, or AVI variant. If the target rejects the first file, inspect its requirements and add options such as -vf scale=1280:720 or a matching -r value rather than assuming that every MJPG AVI is interchangeable.