Free online AVC to XVID converter

What the AVC format is

AVC is Advanced Video Coding, also called H.264 or MPEG-4 Part 10. It is a video codec rather than a container format. Files ending in .avc commonly contain a raw H.264 elementary stream without a separate audio track or metadata container.

Camera recorders, surveillance systems, video encoders, and older authoring tools can export raw AVC streams. H.264 video is also commonly stored inside .mp4, .mkv, .ts, or .mov files; those extensions should be treated as containers, not as evidence that the file is a raw .avc stream.

What the Xvid format is

Xvid is an implementation of the MPEG-4 Part 2 Advanced Simple Profile video codec. It is usually stored in an .avi file, although the codec and the container are separate components. Therefore, an Xvid conversion normally produces an AVI file containing Xvid video, not a distinct Xvid container format.

Xvid remains useful for older DVD players, television media players, embedded systems, and software that supports MPEG-4 Part 2 but not H.264. Its main compatibility advantage comes with legacy hardware; it generally provides lower compression efficiency and lower quality at the same bitrate than AVC.

How to actually convert AVC to Xvid

FFmpeg is the most predictable desktop tool because it can read raw H.264 and select the Xvid encoder directly. Install a build that includes libxvid and, if audio is required, an MP3 encoder such as libmp3lame.

1. Inspect the source with ffprobe input.avc. Confirm the frame size, frame rate, and whether an audio stream exists.
2. For a raw AVC file, run ffmpeg -f h264 -i input.avc -c:v libxvid -q:v 4 -an output.avi. The -f h264 option tells FFmpeg that the input is an elementary H.264 stream, while -q:v 4 selects quality-based encoding; lower values give higher quality and larger files.
3. If the source contains audio in a container, omit -f h264 and encode the audio for AVI compatibility: ffmpeg -i input.mp4 -c:v libxvid -q:v 4 -c:a libmp3lame -q:a 3 output.avi.
4. If FFmpeg reports that libxvid is unavailable, use an FFmpeg build with that encoder or try -c:v mpeg4. The latter produces MPEG-4 Part 2 video, but it is not guaranteed to use Xvid-specific encoding and may have different compatibility characteristics.

For a graphical workflow, Avidemux can open compatible AVC sources; choose Video Output → MPEG-4 ASP (Xvid), select Audio Output → MP3 (LAME) when needed, choose Output Format → AVI Muxer, then save the file with an .avi extension. For a browser-based conversion without installing software, 101convert.com can convert the file for free.

Quality, compatibility, and limitations

The conversion must decode AVC and encode it again as Xvid, so it is lossy and cannot restore detail already discarded by the source. Quality-based encoding is preferable to an arbitrary bitrate; test -q:v 3 through -q:v 6 and inspect the result on the target device.

Raw .avc files often have no audio, timestamps, rotation data, or reliable frame-rate metadata. FFmpeg may need an explicit frame rate, for example -r 25, if playback duration or motion is incorrect. Xvid/AVI compatibility is also limited by the device: some players require MP3 audio, a specific resolution, or a maximum frame rate and bitrate.