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FLV
What is an FLV file?
The Flash era video format. Nothing plays it any more, which is why it needs converting.
What FLV is
FLV is a container: a wrapper that holds streams encoded by something else. It is used for streaming.
The extension is .flv, and the full name is Flash Video. Both matter less than what the file can hold, which is what the rest of this page is about.
Where FLV came from
Adobe published it in 2002.
Age is worth knowing here for one practical reason: the older a format is, the more programs have had time to learn it.
The specification is published, but by its owner
It is written down and implementable, though the vendor decides what the next version looks like. In practice that is enough for the file to keep opening; it is not enough to be sure of it.
It has been superseded
The people who made it have moved on, and support is being withdrawn rather than added. Anything still in this format is worth moving while the tools to move it are still around.
FLV is a box, and the codec is what is in it
It usually holds H.264 and Sorenson Spark. This is the distinction behind most "why will this not play" questions: two files with the same extension can contain entirely different encodings, and a player that refuses one may be perfectly happy with the other.
It also explains why changing container is often fast and lossless while changing codec is neither. Moving the same stream into a different box rewrites the box; re-encoding rewrites the picture.
What else it can carry
FLV can hold a layout that lets it start playing before it has finished arriving.
That matters mostly when converting: whatever the target cannot hold is dropped, usually without a warning.
What opens FLV
VLC and FFmpeg read it, and so do most programs of the same kind.
If a file will not open, the format is rarely the problem — it is more often that the program predates it. Converting to something older is the reliable way past that, and it is what the rest of this site is for.
Opening it in a browser
No browser reads it.
That is the single most common reason to convert it: not that the format is bad, but that the place you want to show the file cannot read it.
It is a delivery format
FLV is meant to be handed over rather than worked in. Editing one is possible and rarely pleasant; the sane approach is to change the source and export again.
What goes wrong with it
The recurring complaints: support outside its home ground is uneven.
None of these is a reason to avoid the format. They are the things worth knowing before you are surprised by one, which is a different claim and a more useful one.
The facts, in one place
| Extension | .flv |
|---|---|
| Media type | video/x-flv |
| Published by | Adobe |
| First published | 2002 |