FormatDrop
How-To Guide

How to Convert FLV to AVI

FLV (Flash Video) was the dominant web video format from 2005 to 2015, used by YouTube, Vimeo, and practically every video website. Adobe Flash is now defunct, and FLV files don't play in modern browsers. Converting to AVI makes the content playable in any desktop media player and importable into video editing software like Premiere Pro, DaVinci Resolve, and iMovie.

Open FLV to AVI Converter

Step-by-step instructions

  1. 1

    FFmpeg (command line — the definitive FLV decoder)

    Re-encode to AVI with H.264 video and MP3 audio: `ffmpeg -i input.flv -c:v libx264 -crf 23 -c:a libmp3lame -b:a 192k output.avi`. For the most compatible AVI: `ffmpeg -i input.flv -c:v mpeg4 -q:v 4 -c:a libmp3lame -b:a 192k output.avi` (older MPEG-4 codec works in every AVI player). If the FLV has no audio: omit the audio flags. Check what's in the FLV first: `ffprobe input.flv`.

    Go to converter
  2. 2

    VLC (GUI, cross-platform)

    VLC → Media → Convert/Save → add the FLV → Convert/Save → set profile to 'Video - H.264 + MP3 (MP4)' → change container to AVI in the profile editor. Configure video codec (H.264 or MPEG-4) and audio codec (MP3). Set output filename with .avi. Click Start. VLC handles FLV decoding well including H.263, On2 VP6, and Sorenson Spark codecs commonly found in old FLV files.

  3. 3

    HandBrake (GUI, for quality control)

    Open HandBrake and select the FLV source. Change the output container to AVI (note: newer HandBrake versions may not list AVI — use MP4 or MKV instead, which are more compatible). Set video codec to H.264. Set RF to 23 for balanced quality. HandBrake shows a real-time preview, letting you check quality before committing to the full encode.

  4. 4

    Online converters (for single files, no software)

    For one-off conversions without installing software, use online converters like Convertio or CloudConvert. Upload the FLV, select AVI output, download the result. These work in the browser with no software installation. Note: upload speed is the bottleneck for large files — older FLV files from YouTube are often low-resolution (240p–480p) and small enough for web upload.

Why convert FLV to AVI?

FLV is a dead format — Adobe killed Flash in 2020. Converting to AVI rescues the content so it plays in any modern media player without requiring ancient browser plugins.

Your files never leave your device

FormatDrop runs the conversion engine entirely inside your browser using WebAssembly. No file upload. No server. Nothing stored. You can verify this by opening DevTools → Network tab and watching: zero upload requests.

Frequently asked questions

What codec is inside my FLV file?
Run `ffprobe input.flv` to see the video and audio codecs. Common FLV video codecs: Sorenson Spark (H.263 variant, early YouTube), On2 VP6 (standard YouTube 2007–2010), and H.264 (later YouTube FLV). Common audio codecs: MP3, AAC, or Speex. FFmpeg decodes all of these. Knowing the codec helps you understand why the file looks or sounds the way it does when converted.
Will FLV to AVI increase the file size?
It depends on the target codec. Re-encoding to H.264 AVI at CRF 23 will often produce a file similar in size to the original FLV H.264. Converting from an old Sorenson Spark or VP6 FLV to modern H.264 at the same visual quality usually produces a smaller file — modern codecs are more efficient. AVI with MPEG-4 or H.264 codec is slightly larger than equivalent MKV/MP4 due to container overhead, but this is negligible.
Should I convert FLV to AVI or MP4?
MP4 is the better choice for most use cases: it's smaller, more widely supported on mobile and smart TVs, and handles subtitles. AVI is appropriate when the destination software is an older Windows video editor that specifically requires AVI input, or when you need compatibility with very old hardware (DVD recorders, older set-top boxes). For modern use: FLV → MP4 is more practical than FLV → AVI.
Convert FLV to AVI Now — Free

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