FLV File Format (.flv)
An FLV file holds video and audio in tagged chunks meant to be streamed to Adobe's Flash Player, which is the only thing that ever played the format natively and has not shipped since the end of 2020.
FLV at a glance#
| Full name | Flash Video |
|---|---|
| File extension | .flv |
| Category | Video Files |
| Developer | Macromedia, later Adobe |
| First released | 2003 |
| MIME types | video/x-flv |
| Compression | Lossy |
| Specification | Adobe Flash Video File Format Specification, Version 10.1 |
| FileFlip support | FileFlip reads and writes this format |
What a .flv file can hold#
These are the things a FLV file either supports or does not, and they are what decides whether a conversion keeps everything or quietly drops something.
| Embedded metadata | Yes |
|---|---|
| Audio | Yes |
| Video | Yes |
| Subtitle tracks | No |
| Chapters | No |
| Streaming | Yes |
Strengths and limitations of FLV#
What FLV does well
- Small enough at dial-up and early broadband bitrates to make web video work at all
- Played through Flash Player, which sat on very nearly every desktop browser of its era
- Streamed over RTMP, so video started playing long before the file finished arriving
- Later files carry H.264, which still decodes on modern hardware once it is out of the FLV wrapper
Where FLV falls short
- Adobe ended Flash Player support on 31 December 2020 and started blocking Flash content on 12 January 2021
- No browser, phone, console or television made in the last decade opens an FLV
- Older files use Sorenson Spark or VP6, codecs no current encoder targets and few tools still decode
- No subtitle or chapter tracks, so anything a Flash player overlaid on the video lived outside the file
There is no reason to create an FLV now; the only sensible use is holding on to one as the untouched original of something you have already converted.
Convert FLV to MP4 as soon as you find one, since the wrapper is the only thing standing between you and video that still plays perfectly well.
How to open a .flv file#
A .flv file opens in the programs below, grouped by the platform you are on. If you would rather not install anything, FileFlip converts FLV into a format your machine already opens, and it does it in the browser tab rather than on a server.
| Platform | Programs that open it |
|---|---|
| Windows | VLC, MPC-HC, PotPlayer |
| macOS | VLC, IINA, mpv |
| Linux | VLC, mpv |
| Android | VLC, MX Player |
| Web | FileFlip |
FLV questions people ask#
Is FLV dead?
FLV is dead as a delivery format. Adobe stopped supporting Flash Player on 31 December 2020 and began blocking Flash content from running on 12 January 2021, and browsers had already removed the plugin before that. Nothing on the modern web plays FLV. The video inside an old file is usually still perfectly good, which is why converting rather than discarding is the right move.
How do I open an FLV file?
VLC opens FLV files directly on Windows, macOS and Linux, and it is the most reliable way to watch one without converting anything. Players built on FFmpeg, mpv among them, read the format too. What will not work is double-clicking the file and hoping the system handles it, because no operating system has shipped FLV support since Flash was retired.
What codec is inside an FLV file?
FLV is a container, and which codec it holds depends on when the file was made. Early files use Sorenson Spark, then VP6 became common, and H.264 arrived with Flash Player 9 Update 3 in December 2007. Audio is usually MP3, Nellymoser or AAC. This matters when you convert: knowing what is inside tells you whether the video can be rewrapped untouched or has to be encoded again.
Does converting FLV to MP4 lose quality?
It depends entirely on the codec inside the FLV. A later file holding H.264 can be remuxed into MP4, which lifts the same video stream into a new container and loses nothing at all. An older file holding Sorenson Spark or VP6 has to be re-encoded, because MP4 cannot carry those codecs, and re-encoding always gives up a little detail. Either way the picture cannot get better than the FLV was.
What was FLV used for?
FLV was how video reached the web through the 2000s. Sites embedded a Flash player and streamed FLV to it over RTMP or plain HTTP, which sidestepped the codec and plugin mess of the time by relying on Flash being installed everywhere. YouTube launched on Flash in 2005 and switched to HTML5 as its default player in January 2015, which is roughly the arc of the whole format.
Converting FLV files#
Convert FLV to another format
Convert another format to FLV
Every conversion runs inside your browser. The file is read from your disk, the work happens on your own machine, and nothing is uploaded. How FileFlip works names the engine behind each family and how to verify that for yourself.