Free online FLV to XVID converter

Older media players, DVD players, and editing programs may accept an AVI file encoded with Xvid but reject an FLV file. Converting the video changes its codec and usually its container, so the result can be shared or opened by software that lacks FLV support.

What the FLV format is

FLV, or Flash Video, is a container designed for playback through Adobe Flash Player. Older websites, browser-based video services, screen-recording tools, and Adobe Flash Media Encoder commonly produced FLV files. The container may hold video encoded with Sorenson Spark, VP6, or H.264 and audio encoded with MP3 or AAC.

FLV became uncommon after browser vendors ended Flash support, but it still appears in archived web downloads, legacy media libraries, and exports from older recording software. The .flv extension identifies the container, not one specific video codec.

What the Xvid format is

Xvid is an open-source implementation of the MPEG-4 Part 2 Advanced Simple Profile video codec. It is a video codec rather than a container; an “Xvid file” normally means an AVI file containing Xvid video, often with MP3 audio.

Xvid is useful for older televisions, standalone DVD or media players, editing applications, and systems that support MPEG-4 ASP but not newer codecs. It can produce much smaller files than uncompressed video, but H.264 and H.265 generally provide better quality at the same bitrate. Xvid also does not preserve modern H.264 features such as B-frame profiles and some advanced metadata.

How to actually convert FLV to Xvid

Using FFmpeg

FFmpeg is the most controllable desktop method. Open a terminal in the folder containing the source file and inspect it first:

ffmpeg -i input.flv

Convert the video to Xvid in an AVI container and the audio to MP3:

ffmpeg -i input.flv -c:v libxvid -q:v 4 -c:a libmp3lame -q:a 3 -f avi output.avi

-c:v libxvid selects the Xvid encoder, while -q:v 4 uses quality-based video encoding; lower values produce higher quality and larger files. -c:a libmp3lame creates broadly compatible MP3 audio, and -q:a 3 selects variable-bitrate audio quality. The .avi extension and -f avi specify the usual Xvid-compatible container.

If FFmpeg reports that libxvid or libmp3lame is unavailable, install a build compiled with those libraries or check available encoders with ffmpeg -encoders. Do not simply rename input.flv to output.avi; changing the extension does not convert the streams.

Using Avidemux

In Avidemux, open the source with File → Open, choose Mpeg-4 ASP (Xvid) under Video Output, select MP3 (LAME) under Audio Output, and choose AVI Muxer under Output Format. Set the video quality or target bitrate, then use File → Save and give the output an .avi filename. Menu labels can vary between Avidemux versions.

Using the built-in online converter

You can convert the file on 101convert.com for free without installing software. Upload the FLV, select Xvid or an AVI/Xvid output when offered, start the conversion, and download the resulting file. Avoid uploading confidential or copyrighted material unless the service terms and your rights permit it.

Quality, compatibility, and limitations

Re-encoding is lossy. If the FLV already contains H.264, converting it to Xvid decodes and recompresses the image, so some detail will be lost even when the output resolution is unchanged. Preserve the original frame size and frame rate unless the target device requires a different setting; upscaling cannot restore detail.

For a fixed file size, use two-pass encoding instead of quality mode. For example, replace the video options with -b:v 1200k -pass 1, run the command with no audio output to create the first pass, then run a second pass with -pass 2 and the desired audio options. Quality mode is simpler when the target size is not predetermined.

AVI/Xvid compatibility is highest with standard-definition resolutions, MP3 audio, and conventional frame rates such as 25 or 29.97 fps. Some older hardware rejects variable frame rate input, unusual image dimensions, AC-3 or AAC audio, or very high resolutions. Check the result with ffprobe output.avi or a media player before deleting the FLV.