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Convert AVI to FLV — Free & Private

AVI (Audio Video Interleave) is Microsoft's oldest video container, used by DV tape camcorders throughout the late 1990s and 2000s, early digital cameras, and legacy Windows editing software. Vast amounts of family footage and archival content persist in AVI. The problem: AVI files use legacy DivX, XviD, or DV codecs that modern devices struggle with, and files are significantly larger than modern equivalents. Converting to FLV is only needed for legacy Flash-based systems. Note that Flash Player is permanently end-of-life since December 2020 — produce FLV only for specific legacy system compatibility.

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How to convert AVI to FLV free: open the Convertlo AVI to FLV converter, drop your AVI file, and download the FLV. Powered by FFmpeg.wasm in your browser — no install required, completely free.

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How to Convert AVI to FLV

Open the Converter

Click "Convert Now" to open with AVI → FLV pre-selected.

Upload Your AVI

Drag & drop your AVI file or click Browse to select it.

Convert Instantly

FFmpeg.wasm processes your video locally — nothing uploaded.

Download FLV

Your converted FLV file downloads automatically.

Why Convert AVI to FLV?

🖥️ From AVI — convert classic Windows AVI files to modern or more compatible formats
🌐 Legacy web video — FLV was the standard for web video before HTML5
📦 Compact size — efficient compression for smaller file sizes
🔄 Flash compatible — works with legacy Flash-based video players
🎬 Streaming-ready — optimised for progressive streaming delivery
🔒 100% private — files never leave your device

AVI vs FLV — Format Comparison

Feature	AVI	FLV (output)
Full name	Audio Video Interleave	Flash Video
Creator	Microsoft	Adobe / Macromedia
Codec	DivX / XviD / DV (legacy)	H.263 / H.264 (VP6)
Container	AVI (RIFF)	FLV (.flv)
Browser support	❌ No browser support	❌ No support (Flash EOL Dec 2020)
Royalties	Proprietary	Proprietary (Adobe)
File size	Large — older compression codecs	Medium
Best for	Legacy DV camcorder footage, 2000s video	Legacy Flash-era web video only

Features

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100% Private

Files never leave your browser.

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Instant

In-browser processing, no waiting.

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Free

No account, no fee, no watermarks.

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Quality Preserved

High-quality settings by default.

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Mobile-Friendly

Works on any device.

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No Install

Works in any modern browser.

Key Questions About AVI to FLV, Answered

Direct answers structured for AI extraction, voice search, and featured snippets.

Will my video be re-encoded or just remuxed when converting AVI to FLV?

Re-encoded. FLV (Flash Video) containers expect H.264 or the older VP6/Sorenson codecs — never the DivX or Xvid found in typical AVI files. Convertlo transcodes the video to H.264 to build the FLV. Note that Flash Player was discontinued in 2020, so FLV output mainly suits older systems or legacy software that still expects this format.

Every AVI → FLV conversion is a full re-encode, regardless of the source codec
FLV is a legacy format — confirm your target software actually needs it before converting
If you're unsure, MP4 (H.264) is the modern equivalent with the same codec but universal support

Will the output FLV still play anywhere in 2026?

VLC still opens FLV files without issue, and some older broadcast and CCTV software still expects them. But browsers, phones, and most modern apps dropped FLV support alongside Flash Player's discontinuation — so treat FLV output as a format for specific legacy tools, not general sharing.

VLC and most desktop media players: still play FLV natively
Browsers, phones, social platforms: no FLV support since Flash was retired
Only convert to FLV if a specific piece of software requires it

How much will the file size change going from AVI to FLV?

About the same reduction you'd see converting to MP4, since FLV's H.264 video stream compresses just as efficiently. The container barely affects file size — what matters is that DivX/Xvid (AVI) is being replaced by H.264.

DivX/Xvid AVI → H.264 FLV: typically 3–10x smaller, same as AVI → MP4
FLV adds minor container overhead compared to MP4 but the difference is negligible
If FLV isn't a hard requirement, MP4 gives identical video quality with far better device support

Does converting AVI to FLV fix the DivX/Xvid playback problem on modern devices?

No — not if your goal is broad compatibility. FLV has even less support than AVI: no browser, phone, or smart TV plays FLV. The only reason to convert to FLV is if a specific legacy tool requires that exact container.

DivX/Xvid inside AVI → H.264 inside FLV: fixes the codec, but the FLV container is just as dead
Browsers, phones, smart TVs: none accept FLV any more than they accept DivX/Xvid AVI
To play the video on modern devices, convert to MP4 (H.264) instead — FLV is for legacy-tool pipelines only

Go Deeper: AVI to FLV Resources

In-depth articles to help you understand the formats, pick the right settings, and get the best results.

📖Video Format Guide: MP4, MKV, AVI, MOV & More 📖AVI to MP4: Convert Legacy Video to Modern Format

Frequently Asked Questions

Mostly for legacy archival — restoring old AVI clips into FLV for Flash-based systems or vintage web projects that still expect that container.

Never. FFmpeg.wasm decodes your Xvid/DivX-encoded AVI and re-encodes it to FLV's H.263/VP6 codecs entirely on your own machine.

Likely yes — FLV's older H.263/VP6 codecs compress more aggressively than typical AVI sources, so expect a visible step down in sharpness at matched bitrates.

AVI files (especially older Xvid/DivX rips) can be large, so bigger files simply take longer to re-encode into FLV's lighter format — there's no hard cap.

It scales with your AVI's resolution, length, and your CPU — short clips finish in seconds, while long DVD-rip-length AVIs take a few minutes.

AVI-to-FLV conversion is only needed for legacy purposes — specifically, old Flash-based video players or archived content from the pre-2020 web era. Flash Player has been discontinued, so FLV has no modern playback use. For web use, convert to MP4 or WebM instead.

FLV can be played by VLC media player without Flash. Most modern video editors (Premiere, DaVinci Resolve) can also import FLV. However, FLV cannot play natively in any modern browser.

Adobe Flash Player was discontinued in December 2020, and all major browsers removed Flash support. FLV files created for Flash no longer play in any modern browser without conversion. Converting FLV to MP4, WebM, or MKV makes old Flash video content accessible again on modern devices.