How do I play an FLV file?

VLC, MPV and PotPlayer play nearly every FLV file on desktop. Browser support varies: modern Chromium, Firefox and Safari play common containers via the HTML5 <video> tag, but niche FLV variants may fail. If a device refuses your FLV, convert to MP4 with our FLV to MP4 converter for universal playback.

AVI vs FLV — Differences, File Size & When to Use Each

AVI vs FLV

A detailed comparison of AVI Video and Flash Video — file size, quality, compatibility, and which format to choose for your workflow.

Convert AVI → FLV Convert FLV → AVI

AVI

AVI Video

Video Files

AVI is a legacy Microsoft multimedia container that stores audio and video data. While largely superseded by modern formats, it remains widely recognized and is produced by many older devices and screen recorders.

About AVI files

FLV

Flash Video

Video Files

FLV was the dominant web video format during the Flash era. While Flash is now deprecated, many legacy video files still exist in FLV format and need conversion to modern formats.

About FLV files

Strengths Comparison

AVI Strengths

Simple, well-documented format — trivial for any video library to parse.
Universal Windows playback since Video for Windows in 1992.
Low encoding overhead — interleaved structure is fast to write.
Works with any codec technically, including modern ones.

FLV Strengths

Low overhead — the container is extremely compact.
Designed for streaming — progressive download and seeking work well.
Decoded natively by Flash Player on every OS for 20 years.

Limitations

AVI Limitations

Aging container — no native support for chapters, subtitles, or multi-audio selection.
File-size limits (2 GB original, 4 GB with OpenDML) break for HD content.
Variable-framerate video causes sync drift.
Larger than equivalent MP4 or MKV due to container overhead.
Poor support on iOS and Android.

FLV Limitations

Flash Player is dead — no modern browser can play FLV without conversion.
Legacy codecs (Sorenson, VP6) are poorly supported in modern tooling.
Hardware video decoders never added FLV support.
Metadata format is primitive compared to MP4 or MKV.
Actively harmful to use today — every major security agency has warned against Flash since 2015.

Technical Specifications

Specification	AVI	FLV
MIME type	video/x-msvideo	video/x-flv
Extension	.avi	—
Container	RIFF	—
Max file size	2 GB (original); 4 GB (OpenDML extension)	—
Codec support	Any codec via FourCC identifiers	—
Extensions	—	.flv, .f4v
Video codecs	—	Sorenson Spark, VP6, H.264 (F4V)
Audio codecs	—	MP3, Nellymoser, AAC
Status	—	Deprecated since December 31, 2020

Typical File Sizes

AVI

10-min video (XviD / MP3) 100-200 MB
45-min TV episode (DivX) 350-700 MB
2-hour movie (DVD rip) 700 MB - 1.4 GB

FLV

10-min YouTube 2008-era video 40-80 MB
45-min TV show (FLV H.264) 200-500 MB

Ready to convert?

Convert between AVI and FLV online, free, and without installing anything. Encrypted upload, automatic deletion after 2 hours.

Convert AVI to FLV Convert FLV to AVI

Frequently Asked Questions

AVI (Audio Video Interleave) is a multimedia container format introduced by Microsoft in 1992. It interleaves audio and video data streams and supports various codecs, though it lacks native support for modern features like subtitles and chapters.

FLV (Flash Video) is a video container format that bundles one or more video streams, audio tracks, and optional subtitles into a single file. The container format determines how metadata is organised and which codecs can live inside; the visual quality itself depends on the codec (H.264, H.265, VP9, AV1) rather than the FLV wrapper. It is part of the video files family.

AVI files play in VLC (recommended, free), Windows Media Player, KMPlayer, and most video editing software. Some AVI files may require specific codec packs depending on the encoding used.

VLC, MPV and PotPlayer play nearly every FLV file on desktop. Browser support varies: modern Chromium, Firefox and Safari play common containers via the HTML5 <video> tag, but niche FLV variants may fail. If a device refuses your FLV, convert to MP4 with our FLV to MP4 converter for universal playback.

MP4 is the better choice for almost all modern uses since it offers better compression, wider compatibility, and support for subtitles and chapters. AVI is mainly encountered with legacy video files and older camera recordings.

Upload your FLV to KaijuConverter and pick MP4, MOV, MKV, WebM, or any other target. Our pipeline uses FFmpeg under the hood and stream-copies when codecs are compatible (no quality loss) or transcodes at high-quality defaults otherwise. Conversion runs server-side; both files delete within two hours.