What is FLV (Flash Video)?
Complete guide to the FLV file format
Last updated:
What is FLV (Flash Video)?
FLV (Flash Video) is a legacy video format that was used to deliver video on the web through Adobe Flash Player. It was the dominant web video format from 2003 until Flash Player was discontinued in 2020.
FLV files were used by YouTube, Hulu, and virtually every major video platform before HTML5 video replaced Flash. FLV is now essentially obsolete but many legacy video files still exist in this format.
How FLV Works
FLV uses a simple tag-based container: a short file header is followed by a sequence of tags, each carrying audio, video, or scripted metadata along with a timestamp.[2] Early FLV files typically carried Sorenson Spark or VP6 video, while later versions added support for H.264 video and AAC audio.[3] A related format, F4V, was introduced by Adobe based on the ISO Base Media File Format to carry H.264 content more efficiently than the original FLV structure.[3]
Decline and Replacement
FLV's dominance was tied directly to the ubiquity of Adobe Flash Player as a browser plugin, the only reliable cross-browser video runtime of its era.[3] The rise of the HTML5 <video> element, which plays MP4, WebM, and Ogg natively without a plugin, removed the technical need for Flash-based delivery.[1] Adobe ended Flash Player support at the close of 2020, after which browsers blocked the runtime entirely, leaving FLV as a legacy archival format.[3]
Technical Details
FLV vs Other Video Formats
| Feature | FLV | MP4 | WebM |
|---|---|---|---|
| Type | Container[2] | Container | Container |
| Codec(s) | VP6, H.264[3] | H.264, HEVC, AV1 | VP8, VP9, AV1 |
| Device/browser support | Legacy Flash, deprecated[1] | Universal | Modern browsers |
| Standardized by | Adobe[2] | ISO/IEC | Google / open |
| License | Proprietary | Standardized | Royalty-free |
| Best for | Old Flash video | Modern streaming | Open web video |
FLV depended on the now-discontinued Flash Player; MP4 and WebM are today's web delivery formats.
Pros and Cons
Advantages
Some older media players and systems can still play FLV files.
FLV was the universal web video standard for over a decade.
FLV files were optimized for web streaming with reasonable file sizes.
Many archived web videos from 2003-2015 exist in FLV format.
Disadvantages
Flash Player was discontinued in December 2020 - FLV is no longer supported by browsers.
No modern browser, phone, or tablet can play FLV without conversion.
Flash Player had numerous security vulnerabilities leading to its discontinuation.
FLV codecs (H.263, VP6) are significantly inferior to modern H.264 and H.265.
When to Use FLV (Flash Video)
Here are the most common situations where FLV (Flash Video) is the right choice:
Legacy Content Archival
FLV is used when accessing archived web content from the Flash era.
Video Conversion Source
FLV files are common source files for converting to modern formats like MP4.
Digital Preservation
Archivists work with FLV when preserving historical web video content.
Nothing Modern
FLV should not be used for any new video content - use MP4 or WebM instead.
Convert FLV (Flash Video) Files
Need to convert your FLV files? Use our free online converter.
Try Video Converter FreeFrequently Asked Questions about FLV (Flash Video)
How do I play FLV files?
VLC media player can play FLV files. No web browser can play FLV since Flash was discontinued.
How do I convert FLV to MP4?
Use our free online converter or VLC media player to convert FLV to MP4 for modern compatibility.
Is FLV still used?
No, FLV is obsolete. Flash Player was officially discontinued in December 2020.
Can I play FLV on my phone?
Most phones cannot play FLV natively. Install VLC for mobile to play FLV files.
Why was Flash/FLV discontinued?
Adobe Flash had persistent security vulnerabilities and was incompatible with mobile devices, leading to HTML5 video replacing it.